ESE's works engine tuner

[TZ350]

321159

The four stroke version of Ecotrons software has multi tooth capability but I think that like some other features this is turned of in the two stroke version, or my version at least. This may have been an option selected at time of purchase, I guess it could be changed.

321160

Flettner has his injectors in the rear transfer boost port cutaway.

321161

It is not possible for me to put my small injector in the boost port cutaway like Flettner has but I might be able to bring it through the side on an angle. The mixing should be better than in the back of the cylinder where it is now.

[TZ350]

"" I did a test on the carbureted version of at each throttle position to record the EGT that was giving the proper performance. Once running with the EFI I tried to tune it to achieve the same EGT numbers as the carburetted versions.

In total I ran for 3 hours on the dyno and ended up with 10% more power everywhere!

The only sensors I used Were Throttle position, engine RPM, Crank Angle, and Water Temp for initial start up enrichment.

How did I get an injector to fire every cycle at 15,000 rpm ?????? I didnt! What I did is used a butterfly Janvey 41mm throttle body with 2 injectors on the engine side of the butterfly. That way When the throttle is closed, fuel still feeds the engine to lubricate it like a Jet Pilot Would do. To get 15,000 RPM, I Had Each injector firing at alternating engine revolutions. Thereby the injectors Were seeing 7500 at 15000rpm pulse of engine speed. I tricked 'em into thinking This was a 2 cylinder 4 cycle engine firing in tandem.""

I like the idea of recording EGT numbers from carburettor runs at different throttle positions. (Wob has suggested the EGT thing too).

I too found it relatively easy to make power and to get it to start and idle easily, my problem is getting it drivable on the track, I would love to know if Riley ever took his to the track and how it went.

Clever idea halving the apparent rpm that each injector sees. The actual fuel delivery window time is still only 15,000rpm wide but the apparent 7,500rpm gives each injector time to wind up and close down either side of the 15,000 rpm window.

That way you can use a smaller injector to deliver the same amount of fuel in the 15,000rpm wide window as a much bigger one. Because a bigger one running full speed uses up much of the 15,000rpm window time getting itself open before it can deliver any fuel and there still has to be time left for closing and resting.

At 15,000 rpm the injector has to be big enough to deliver a large dolop of fuel in a very short space of full flow time, the half speed injector gets a much longer space of full flow time.

If we can open and close plus rest an injector either side of the fuel injection window by halving the apparent rpm to 7,500rpm. It may allow one to use an injector that is only a third the size of a suitable injector for full time 15,000rpm fuel injection. And that 7,500 rpm injector could be small enough to give the full tunable range from closed throttle to full throttle at maximum torque rpm.

I guess Riley just lucked in with using a 4T EFI unit, probably the only thing available at the time. Lucky Bugger, I made the mistake of going for a 2T specific unit.

Now that I know a bit more about 2T EFI, Riley's method of a 4 cylinder 4T firing 2 cylinders in tandem looks like a very good idea.

But because the squirt time will be much smaller than the window time we will still have the fuel homogenization issue at high rpm low throttle problem, I wonder how Riley got on.

4 cylinder 4T firing 2 cylinders in tandem, Ecotrons software could do it but without a cam sensor the software looks at the MAP sensor to tell which cylinder is on the injection stroke. And a MAP sensor is pretty useless on a single cylinder two stroke.

[ken seeber]

If the issue is one of cyclic speed variation (due to random/spurious fuel quantities in successive combustion events as per Mooooools point), one way to ascertain the need for a greater crank position resolution (ie more actual functioning teeth) would be to add a decent size external flywheel. If this makes any difference at all, then this would tell you, yay or nay, that you do need greater resolution for the ECU.
Of course, this would affect the performance on an inertia dyno, but at this time the issue is one of fundamental operation.

[TZ350]

If the issue is one of cyclic speed variation (due to random/spurious fuel quantities in successive combustion events as per Mooooools point), one way to ascertain the need for a greater crank position resolution (ie more actual functioning teeth) would be to add a decent size external flywheel. If this makes any difference at all, then this would tell you, yay or nay, that you do need greater resolution for the ECU. Of course, this would affect the performance on an inertia dyno, but at this time the issue is one of fundamental operation.

Thanks for the tip, yes at the moment it is about fundamental operation, been there, done that with maximising the EFI's performance.

[TZ350]

.

Plenty to do now, thanks everyone for the helpfull suggestions.

[cotswold]

Can any one give me the cylinder stud spacings for their water cooled 50's, I have a project engine I am playing with and it has a 70 kit I want to ditch and replace with a 50, mine has studs spaced square 52mm. Also the original 50 cylinder is fuel injected into the head so also want to ditch that, already have the case set up for reeds.
Thanks

[TZ350]

Interesting project. tell us more ..... :D

[cotswold]

Interesting project. tell us more ..... :D

When I find a cylinder I can make fit I hope to build a lazy mans 50cc race bike using a recently bought SR50 motor. It has some go faster bits, Engine currently has
-Malossi 70cc cylinder
-Malossi crankshaft
-Malossi ecu
-Malossi aluminium piston
-Malossi multivar kit
-Malossi drive belt

All after market bolt on scooter bits but want that pesky 70 kit gone

[jonny quest]

If I'm reading this correctly, your issue is off idle performance after a wide open run. Does that have nothing to do with a single injector trying to cycle at 15k?

[Flettner]

321134

My side injectors are aimed across the transfer ports to hopefully get some fuel into both the A and B ports.

321132

Hard to do on an air cooled motor. But I would have prefered to have my injectors vertical and spraying against the air flow as I think this is the best way to get good mixing.

I think this is Flettners YZ250 cylinder. It only has injectors in the B ports but it runs Ok, in fact very well. The difference between a YZ250 and my 125 is that the YZ is running E85 and less than 9,000 rpm. Above 9K seems to take 2T EFI onto another level of complexity.

No, the YZ runs petrol and yes it's all over at 9000 rpm.
The F9 runs E90 and it also signs off at 9000 rpm (not bad I thought for and old 1973 shit cylinder) but yes not more than 9000.
My new 360 EFI engine has the injectors across the cylinder as you have done TZ, plus one up it's back port:innocent:

[sonic_v]

Can any one give me the cylinder stud spacings for their water cooled 50's, I have a project engine I am playing with and it has a 70 kit I want to ditch and replace with a 50, mine has studs spaced square 52mm. Also the original 50 cylinder is fuel injected into the head so also want to ditch that, already have the case set up for reeds.
Thanks

AM6 cylinders have 52mm square. Still plenty of 50cc aftermarket cylinders though some are coming with a 40.00 mm bore instead of the standard 40.30 mm. This might be useful if your stroke is longer than the am6 39.00 mm.

[TZ350]

If I'm reading this correctly, your issue is off idle performance after a wide open run. Does that have nothing to do with a single injector trying to cycle at 15k?

15k was Rileys EFI 2:1 injector example my engine tops out about 12250 rpm.

321172

So no, I do not think so, the injector performs perfectly at max load and rpm. The running problem is when the injector is asked to deliver fuel for less time than the transfer duration.

The only suspicious issue is the minimum injection on time. I may have it set to low, I have it set to 1 ms. On over run the map calls for 1.15 ms. so basically 0.15 of fuel delivery time. But if it really takes a minimum 1.4 ms to open the injector then its short 0.25 ms and if I set the minimum on time to 1.4 ms then the injector can't be turned down enough and over fuels by 0.25 ms.

[dark art]

The only suspicious issue is the minimum injection on time. I may have it set to low, I have it set to 1 ms. On over run the map calls for 1.15 ms. so basically 0.15 of fuel delivery time. But if it really takes a minimum 1.4 ms to open the injector then its short 0.25 ms and if I set the minimum on time to 1.4 ms then the injector can't be turned down enough and over fuels by 0.25 ms.

Is there any way to ajdust the ECU so the injector only sprays on alternate cycles, like a foul-stroke?
May not be the best solution but maybe enough to verify if the problem is minimized, it will four-stroke anyway....

[MotleyCrue]

I've been searching the World Wide Web, but haven't found anything, which I'm surprised.

Looking for some pipe specs for a NSR250 MC21. Stock, or aftermarket.... even both preferably. I don't have bike yet, so I can't do any measuring, trying to get a good start on how I want to dimension out the 2 into 1 I'm going to build for it.

https://youtu.be/hGAR539cmAs

I have never been able to get this lovely sound out of my head, I will gladly lose some HP to have my NSR sound like this.


Banshee 2 into 1 is the only 2 into 1 I have ever heard that sounds like that. Wobbly messed around with 2 into 1 engines of some sort and Banshee engines too I think, so maybe he knows why they sound like that but many other 2 into 1s dont. The Banshee 2 into 1 pretty much sounds like NA F1 engines did.

[Frits Overmars]

I have never been able to get this lovely sound out of my head, I will gladly lose some HP to have my NSR sound like this.You will lose power but I'm afraid you'll get nothing in return. The NSR is a 90° V-twin, isn't it? You can forget about the nice sound then.
In a normal expansion pipe there is one strong pulse between exhaust opening and exhaust closure, followed by a second, weaker pulse between exhaust closure and exhaust opening with a somewhat lower frequency because of the lower gas temperature and the accordingly lower speed of sound during this second phase.
But if you couple the exhaust ducts of two cylinders that fire 180° apart, all pulses in the pipe will be identical and the sound will be quite musical.
And talking about musical, you might want to find a sound track of a four-cylinder König boxer engine with two 2-in-1 pipes.
3-in-1 pipes on Suzuki and Kawasaki triples also sounded lovely, but also at the cost of quite some power.

[cotswold]

AM6 cylinders have 52mm square. Still plenty of 50cc aftermarket cylinders though some are coming with a 40.00 mm bore instead of the standard 40.30 mm. This might be useful if your stroke is longer than the am6 39.00 mm.

Thanks Sonic, that is what I was hoping for.

[jonny quest]

Yes, the NSR250 is a V. I thought it still fired 180, I don't have motor in front of me yet. But I suppose that would be hard if the crank pins are 180deg apart, and motor is in a V configuration.

[mr bucketracer]

15k was Rileys EFI 2:1 injector example my engine tops out about 12250 rpm.

321172

So no, I do not think so, the injector performs perfectly at max load and rpm. The running problem is when the injector is asked to deliver fuel for less time than the transfer duration.

The only suspicious issue is the minimum injection on time. I may have it set to low, I have it set to 1 ms. On over run the map calls for 1.15 ms. so basically 0.15 of fuel delivery time. But if it really takes a minimum 1.4 ms to open the injector then its short 0.25 ms and if I set the minimum on time to 1.4 ms then the injector can't be turned down enough and over fuels by 0.25 ms.are you running a tps on it?

[wobbly]

The NSR and RGV and RS250 all have the pins inline at 0* so fire the cylinders at 0 - 90 as per the V angle.
Honda made the later RS250 GP bike 72* I think, but the crank has an odd pin offset , so I cant remember if that is an odd fire setup.
I Have fitted Ignitechs to several of them,and ground off 3 of the 4 trigger lobes to make them work correctly.

And yes any 180* twin with 2:1 reving its tits off sounds like a screamer, but no matter how good your pipe skills are you wont
get the overall power that two will.
It has been shown to create good bottom to mid power - but if the twin pipes were redesigned for that power range, then they would make even more down there.
And in the work I have done on the 180* 2:1 pipes the best result was with the Ex at 200*, so that limits its applications.
And then there was the idea of cutting the pistons short over the exhaust port.
This made a shit load of extra power - but would be impossible to jet without fuel injection or pumper carbs.

[jonny quest]

This isn't going to be a track bike. Bottom and mid are good advantage.

So do I press apart the centers and rephase for 180 firing. I wonder how bad crank harmonics would be, and how complicated it would be to change ignition to fire correctly

[Sketchy_Racer]

This isn't going to be a track bike. Bottom and mid are good advantage.

So do I press apart the centers and rephase for 180 firing. I wonder how bad crank harmonics would be, and how complicated it would be to change ignition to fire correctly

The crank would tear itself apart on startup I suspect. The NSR cranks are beautifully designed but only just man enough for the job from what I have learned.

[TALLIS]

are you running a tps on it?

From what I have seen of the throttle design, maybe not. Would it be worth testing with a conventional butterfly efi throttle body with tps, even if injectors are mounted elsewhere?

[ief]

Was looking at a friends setup today (yamaha fs1 rotary 65cc streetbike) whitch had some problems and made power to high in the revs so not to streetable etc etc...

Anyway, bin playing around, suddenly thought i'd try a whole different exhaust slightly inspired by Neels his example and...

I think this could be called a bell shape torque curve :)

Wonder how it would translate into the real world, as allways, haha.

321174

(how it was and what I made of it)

[TZ350]

are you running a tps on it?

321176

Yes. Running a TPS vis RPM ... Alpha-N map

321175

The next step is to try this Ecotrons throttle body with its injector behind the throttle plate.

[wobbly]

No power below 7000, then it doubles from 6Hp to 12 Hp in 2000 rpm.
I think it may be even harder to ride than the other more linear curve, both sure arent ideal.

[mr bucketracer]

321176

Yes. Running a TPS vis RPM ... Alpha-N map

321175

The next step is to try this Ecotrons throttle body with its injector behind the throttle plate.its like its fueling on the running down of the rpm of the engine and giving it fuel at rpm instead of cutting to a idel of the tps off the gas , need to get a A/F reading when running down

[ief]

No power below 7000, then it doubles from 6Hp to 12 Hp in 2000 rpm.
I think it may be even harder to ride than the other more linear curve, both sure arent ideal.

<_<

To much of a bell curve ai... indeed no change below 7000, better suited for a cvt then perhaps (?)

Back to it it is then.

[TZ350]

its like its fueling on the running down of the rpm of the engine and giving it fuel at rpm instead of cutting to a idel of the tps off the gas , need to get a A/F reading when running down

Yes I agree, there is something wrong with the fueling at high RPM low TPS.

This is a small part of a chart recording what the ECU is doing during a dyno session. It can be seen in the chart that the small injector responds Ok to changes in the TPS.

321182

Inside the box.
Top line is RPM.
Blue is TPS.
White is maximum injection time available at that RPM.
Purple is the small injector.

At the left.
It can be seen a section of zero TPS with the RPM running down. The small injector can be seen at its minimum MAP value and the big injector is at zero output.

From looking at a lot of these charts I can see that the RPM trace becomes increasingly erratic when the injection time is less than a third of the maximum available injection on time. A third of maximum possible injection on time is about the same as the transfer open time so I am guessing the transfer period is heavily involved somehow.

Anywhere the injection on time is less than the transfer window open time the RPM trace becomes erratic and increasingly erratic the smaller the injection on time compared to the transfer window open time. This erratic RPM is most noticeable when the TPS is less than 20% and that is where the injection on time is very much less than the transfer window open time.

To a lessor extent this is also true for the big injector too. I think the low load problems are possibly about erratic fuel mixing and maybe the whole fuel charge being blown right through and out the exhaust port or not inducted at all and maybe even building up as a super rich puddle in some hidden corner of the crank case.

321191

It has been a bit of a group effort, hopefully by injecting just behind the throttle plate we will get better mixing , smoother running and a better pickup from a closed throttle.

Anyway, here is hoping, the plan is to try this throttle body with the small injector for improved fuel homogenization, for better slow running and over rev pickup.

Thanks guys, I am looking forward to trying it but it will probably be next week before I get a chance. ....... :niceone:

[MotleyCrue]

And in the work I have done on the 180* 2:1 pipes the best result was with the Ex at 200*, so that limits its applications.
And then there was the idea of cutting the pistons short over the exhaust port.
This made a shit load of extra power - but would be impossible to jet without fuel injection or pumper carbs.

Was the jetting a problem at high rpm or midrange, too lean or too rich, or was there more to it than that ? If jetting was set good for max power and torque then at what other conditions would the mixture be all out of whack and would it be too lean or too rich under these conditions? Also too lean or too rich according to an EGT reading or according to a lambda reading or according to damaged parts?

[Flettner]

Yes I agree, there is something wrong with the fueling at high RPM low TPS.

This is a small part of a chart recording what the ECU is doing during a dyno session. It can be seen in the chart that the small injector responds Ok to changes in the TPS.

321182

Inside the box.
Top line is RPM.
Blue is TPS.
White is maximum injection time available at that RPM.
Purple is the small injector.

At the left.
It can be seen a section of zero TPS with the RPM running down. The small injector can be seen at its minimum MAP value and the big injector is at zero output.

From looking at a lot of these charts I can see that the RPM trace becomes increasingly erratic when the injection time is less than a third of the maximum available injection on time. A third of maximum possible injection on time is about the same as the transfer open time so I am guessing the transfer period is heavily involved somehow.

Anywhere the injection on time is less than the transfer window open time the RPM trace becomes erratic and increasingly erratic the smaller the injection on time compared to the transfer window open time. This erratic RPM is most noticeable when the TPS is less than 20% and that is where the injection on time is very much less than the transfer window open time.

To a lessor extent this is also true for the big injector too. I think the low load problems are possibly about erratic fuel mixing and maybe the whole fuel charge being blown right through and out the exhaust port or not inducted at all and maybe even building up as a super rich puddle in some hidden corner of the crank case.

321191

It has been a bit of a group effort, hopefully by injecting just behind the throttle plate we will get better mixing , smoother running and a better pickup from a closed throttle.

Anyway, here is hoping, the plan is to try this throttle body with the small injector for improved fuel homogenization, for better slow running and over rev pickup.

Thanks guys, I am looking forward to trying it but it will probably be next week before I get a chance. ....... :niceone:

On these low loads, muck around with the injection timing, I found it very important to have the small pocket of fuel delivered at just the right time. What time? I don't know, just adjust it around and see whats happening. You should find a sweet spot where the unusual exhaust noise (talked about both here and with my experiments) goes away. Large on times don't matter so much. On my 350 the difference was gutless to powerful (bottom third throttle) with no fueling changes, only timing.

[wobbly]

Cutting the pistons short over the exhaust made it blubbery rich at low rpm, then it would completely die on transition
off the idle circuit due to being lean.
Once this was fixed it became very rich in the mid band as it came onto the pipe,but at part throttle the same rpm was so lean it would die again,then it was super lean on top.
Getting all this dialed in was VERY hard work with pumper carbs, but as we had good egt and Lambda data from a " normal " running
engine prior to doing the mods we knew what numbers we should have been seeing.
This is why I have been banging on at TeeZee about getting some useable data for his engine, when it is running well, so you know exactly what direction you should be heading in.
The pumper carbs have such a huge number of variables that can be tailored specifically to affect a certain air flow and throttle opening - only
if you know exactly what you are doing, then even the most weird fuel curve can be achieved.
No way would I even attempt to jet a normal venturi carb to run using that piston mod.

[MotleyCrue]

No way would I even attempt to jet a normal venturi carb to run using that piston mod.


I don't think I understand technically why the mixture would vary so much with a cut piston when running a normal carb, at least for a reed engine. Was this a reed valve engine?



What if the engine had of been running on methanol, since there is good tolerance to being too rich, could a regular carb be made to work then?

Aren't all pumper carbs 4T carbs or are there some 2T pumper carbs?

[jonny quest]

TZ350, EFI is very sensitive to TPS setting. Do you have a standard you are sticking too?

[wobbly]

Yes of course running Methanol would make jetting any type of carb way easyer.
The mixture was being affected by pipe pressure when the piston was at TDC,exactly when the reeds are open and case inflow from the carb is highest.
And yes I think the reeds may have been helping some.
The engine I did the piston cut job on was a SeaDoo 951 running in a stock class at the World Champs in Lake Havasu - and yes we won, and no the trick was never detected.
Pumper carbs can be run on anything, but I havnt seen one with an accelerator pump so it may be difficult to get snap throttle response on a 4T - even with an aux venturi system.
Nearly all 2T engines ( sea,snow,kart,chainsaw ) use pumpers, and I personally have never seen one used on a 4T, but there may be classes I know nothing about like Briggs in USA that use them ?

[TZ350]

On these low loads, muck around with the injection timing, I found it very important to have the small pocket of fuel delivered at just the right time. What time? I don't know, just adjust it around and see whats happening. You should find a sweet spot.

Will do. Currently running 180 which seems to work for the big injector. I already have tried 0 - 90 - 180 - 270 for the small injector , but will try a series of much smaller steps.

321202

I now have the Ecotrons EFI throttle body with TPS and Injector all setup to go. It is a conceptual test and if this works better with the small injector firing behind the throttle plate I will see how I can get an injector installed like this behind the ball valve throttle so I can put it back on, I like that ball valve throttle. Dyno is booked for the next few days, so maybe get to try it next week.

[husaberg]

Will do. Currently running 180 which seems to work for the big injector. I already have tried 0 - 90 - 180 - 270 for the small injector , but will try a series of much smaller steps.

321202

I now have the Ecotrons EFI throttle body with TPS and Injector all setup to go. It is a conceptual test and if this works better with the small injector firing behind the throttle plate I will see how I can get an injector installed like this behind the ball valve throttle so I can put it back on, I like that ball valve throttle. Dyno is booked for the next few days, so maybe get to try it next week.

Silly question, (as you have likely posted it numerous times:scratch:) But how does the Ecotrons kit you are using, measure airflow Rob?

[dark art]

Silly question, (as you have likely posted it numerous times:scratch:) But how does the Ecotrons kit you are using, measure airflow Rob?

Not Rob, but it doesn´t.


Yes. Running a TPS vis RPM ... Alpha-N map

[MotleyCrue]

Yes of course running Methanol would make jetting any type of carb way easyer.
The mixture was being affected by pipe pressure when the piston was at TDC,exactly when the reeds are open and case inflow from the carb is highest.
And yes I think the reeds may have been helping some.
The engine I did the piston cut job on was a SeaDoo 951 running in a stock class at the World Champs in Lake Havasu - and yes we won, and no the trick was never detected.
Pumper carbs can be run on anything, but I havnt seen one with an accelerator pump so it may be difficult to get snap throttle response on a 4T - even with an aux venturi system.
Nearly all 2T engines ( sea,snow,kart,chainsaw ) use pumpers, and I personally have never seen one used on a 4T, but there may be classes I know nothing about like Briggs in USA that use them ?


Just a terminology difference your "pumper carb" is my "diaghragm carb" . In my world a "pumper carb" is a regular 4T carb but with an accelerator pump like a Mikuni TM33 pumper carb.

[wobbly]

OH,I get it.
We call them pumpers as they incorporate the fuel pump that feeds directly into the throttle body.
The strictly correct term is diaphragm carb as you say.

[TZ350]

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An air cooled on Meth operates very similar performance wise to a water cooled on petrol, so its a match in heaven.
In fact if its done really well,you can exceed the bmep of a watercooled on good octane fuel, due to the jungle juices very high latent heat of evaporation - and not suffer the usual issues of heat induced power fade.
EngMod will model anything well, it all depends upon the input accuracy, so yes your crap transfer duct geometry is fully accounted for as an input variable.
As you have a dyno you can convert the power figures to crank easy enough, and from the peak Hp rpm you actually see, you can then modify the pipe temp
numbers of that setup, as modeled, to get accurate outputs for future improvements in port or pipe designs.



Does it ever get to the point where it overcools and make consistent jetting difficult?Sure can, not difficult, impossible as the motor can run so cold that the Methanol does not completely evaporate and the engine runs lean. Any more Methanol fuel to richen things up only makes the engine run colder and leaner. You can get to the point where there is raw Methanol dribbling out the exhaust and the motor is still running lean, been there done that.

I had a Suzuki road racer fitted with RD barrels that ran methanol and the trick was to blend the fuel so that the engine temperature was high enough to evaporate all the fuel. For my RD/Suzuki the ideal blend was 50/50 Acetone Methanol, I expect that other motors may require something different so you will have to experiment but 50/50 is a good place to start.

Acetone has a higher octane rating than Methanol, evaporates better, a latent heat of evaporation about half way between petrol and Methanol and Acetone significantly reduces Methanols tendency to detonation when lean and Acetone very much helps keep oil in suspension in Methanol blends. Current unleaded pump fuel seems to blend with Methanol so probably worth a try. Sit a sample of mixed fuel in a glass jar for a few days to see if it separates out.

Use Yamabond on the cases, the only issue I had was oil seals, some coped with Acetone others did not. Suzuki crank oil seals worked best, Yamaha Teflon lipped seals swelled up and were useless. Test the seals you are going to use in a glass of fuel for several days. After a days racing I used to run a petrol mix very rich in oil through the motor to clean out the hydroscopic Methanol mix so that the crank did not rust. The richer in oil the petrol/oil mix can be the better the petrol will run with the Alcohol jetting.


The way to ensure that you don't get the issue that TeeZee describes is to run as high com as you can,and then tune to achieve reasonable egt numbers.

The optimum com-egt is easy enough to dial in on a dyno - but without the egt telling you what is going on then you are working in the dark.

Methanol will run very rich with no power loss,but if you choose say 850* as a baseline and jet to get that, then go up in com and rejet to again get that same egt the power generated will tell you if you are on the right path or not.

Lectrons do have very very good atomization from the flat needle, but the powerjet nozzles are no better than a normal carb. Thus you need to run as rich as you can on the needle and just fine tune with small powerjets.

This can be helped a lot by cutting the nozzle exit at 45* facing downstream, and then drill a small 0.15mm hole in the front side about 5mm up from the end.

The other trick is to run twin powerjets and rpm switch one with an inline solenoid,thus getting the rich mixture needed at peak power, then leaning off over the top of the pipe.


When i say brake dyno i mean an eddy current or similar that allows both constant rpm tests and normal 'runs'... Im sure that doing only constant rpm tests is not ideal. Personally I do a combination of both to tune an engine and so far it has worked well for me, especially when tuning the low throttle area that TZ was talking about... in saying that ive only ever had an eddy current dyno, never an inertia-only dyno, and have developed my own methods of tuning without ever seeing first-hand anyone else's process for tuning a two stroke... maybe its a case of ignorance is bliss, however i find my process to be very quick and very reliable for a wide range of engines.
I find that the lambda sensor is a little slow to react at low revs and part throttle. Its fine at higher revs and higher throttle. By holding the engine at a certain rpm point for 3-5sec at each throttle position it gives the readings time to stabilise and gives much better, more repeatable data. I start by doing a range of fixed rpm tests at different throttle openings, with the revs building higher each test... eg 4000, 6000, 8000, etc at 1/8, 1/4, 1/2, 3/4, full throttle ... By doing this you can easily see the areas that need changing (pilot, slide, needle diameter, clip position, needle taper, main jet, etc). If there is a serious problem with the tune you will always catch it before doing damage as youll see AFR's begin to lean out or detonation begin to show before you get too high in rpm. Once ive done basic tuning like this then i do full runs and constant load testing and fine tune if necessary, but these are normally only very minor changes.



Whether the AFR reading is showing true AFR or not doesnt really matter, the numbers can still be used to tune an engine... around full throttle and peak torque it is fairly reliable to use ~12.5:1 and leaner readings below that, down to around 13.5-14:1 at part throttle/low rpm. Of course you still need to use experience and 'feel' to do the fine tuning but the AFR numbers will get you close. Even if the engine is not actually seeing 14:1 at part throttle/low revs, its still a repeatable data point that can be used to tune an engine. Its certainly a lot better than guessing, especially when tuning the part throttle areas.

My main question to TZ though was why he wasnt using AFRs to tune his engine? Since he has employed a lot of technology so far it seems only a small extra step to be using a wideband O2 senor to help with the fine tuning as it will save a lot of the guess work.


+1 the above.Adding that putting the Lambda in the stinger, seems to be way more stable and repeatable when logging the A/F data.

Using data this way is something that you really dont appreciate how good it is until actually doing it.
Hence TeeZees surprise when I related that every time you change a small item in the engines tune - the dyno result for sure is not telling you
really what you want to know, unless you rejet every time to hit a predetermined baseline.

As Jan Thiel said, most all of the pipe testing at Aprilia was a complete waste of time,when he finally realized alot of the power differences were down
to how the egt reacted to that pipe.
Not that the pipe was "better " for some aspect of scavenging, or trapping efficiency in making more or less power.


Hi.

I'm not allowed to start a new thread, so i will risk an eye..and ask here, if inappropriate please delete.

I have been looking in many books about twostroke engines. and also searched on google, but i never found a definitive answer.

Many gokarts run coolant temperatures around 50-55 degrees C, the same goes for outboard engines, and some run even colder.
I have read about many road race bikes, from 50cc to much larger bikes, that also seems to run at these same temperatures.

Why it is so ? Do twostrokes make most the power within this particular temperature ?

Best regards
KKT



This.
Jan Thiel has tested this at Aprilia, up to even running constant tap water through the cooling system.


The cooler the water, the cooler the case and more importantly the cooler the transfer and Ex port ducting.
This maintains charge density, as well as keeping cool the slug of A/F sitting in the Ex duct waiting to be shoved back in
by the rear cone wave action.
With a new water regime I developed for KZ2 kart engines we run between 40 and 45*.
A 125 cylinder will drop at the very least 2 Hp, when lifted from 50 to 60*C


I originally built the BSL crank with integral pins ( it made the engine 17mm narrower - big deal )
Sadly no matter how it was done, with big radi and shot pienning etc the bastard pins kept cracking.
This was due to some form of harmonic or torsional twist from firing 2 of the 3 cylinders together.
In the end I tried a crank with the same dimensions ie only 12mm of press fit on the side where the pin originally was one piece.
We made a jig that kept the pin dead square in the crank hole, and tigged it right around the outside face.
Never had a crank issue after that.

So I would suggest spark eroding new pin holes, in the integral side,and welding in new pins may in fact work.
But from memory the Honda and the RGV/RS250 may be even thinner than 12mm.

One thing to be aware of - the original crank had the pin holes on the non integral side moved inward 0.008mm,as when the pin was pressed in
the wheel material would bulge outward,changing the stroke length by that amount.
Thats not an issue if both sides are pressed in, and both wheels are identical.

In this case it might take a couple of cranks to get the new hole position dead on such that the thing will straighten correctly due to the thin press width.
Having the stroke lengths not matching is easy to detect, with 2 dial gauges on each end of the same axle, both will rise and fall together - impossible to correct.


Measuring that 0,008 mm would be pretty hard to do most normal measuring gauges go to 0,01mm , unless You are talking inches then 0,008 it's 0,02mm but would that make a big difference? Guys here used to be doing thing like this on RZ cranks since it was cheaper than buying new one from overseas and they were not that available like they are now.


You are not measuring it at all, you would be programming a CNC spark eroding machine to bore the pin hole at a reduced the stroke of 0.008mm.
But if the wheels are thinner than 12mm as the BSL ones were, then 0.01 would probably be closer.
And yes 0.02mm runout in a crank is nowhere near "straight ", it would destroy the main bearing and or fret the cases due to the wobble in no time.
This is why I have probably 10 RZ cases that are junk, because the main bearing journal faces are worn oval, from crank rebuilders who didnt know what they were doing.


Not saying you're wrong Wobbly, but even at ,04mm shouldn't fret or damage cases.

Crank rebuilding is an art, I do a lot of singles, and it's not uncommon to see them come out with 5 hours run time at ,15mm runout.

You put a hairdryer to a crank with ,02mm runout and it will move almost twice that


The problem with the twin is that if you are prepared to accept 0.02mm or 0.03 runout like Yamaha says , then this can be at both ends.
It can also easily be on opposite sides, so in effect you then have 0.06 runout across the outer mains - this is why the tunnels are wreaked, being oval or with no crush
in most every old RD/TZ/RZ case I measure these days.

Edit - yes I agree about cranks moving after being run, but in my opinion this is due to having excessive amounts of hammering to get them " true ".
The metal in close contact is very springy, and I have found that if the wheels are held dead in line in a die set so that there is no need to hammer the shit out of them
they dont move at all.
If hammered they will always spring back a little in the direction they came from.


fs1 problem fixed... in the virtual world that is (inlet tuning, inlet tuning and inlet tuning.... mostly) Had a lot of aha moments, always good.

But have 2 things I can't seem to solve myself. First, I made a pipe with ATAC and it gave 12% more power, that is with the latest beta, even with a wrong collector (bends where wrong) Anyone else noticed this or should I be aware of an easy to make mistake or?

Second is the membrane and resonant frequency. When modeling and measuring my tomos I noticed the membrane was way to stiff so I gave it some more free length, still way above what would be concidered ideal but in practice this didn't work at all, bike started '4stroking' at higher revs so my conclusion was that they didn't close fast enough. (though it could (could it?) be something else...)

edit: lol, something popped in my mind, inlet tuning? :D The pipe between carb and cilinder is pretty long on the tomos. (but still, engmod didn't show a problem as far as I am aware)

Any thoughts on that one?


The 1st harmonic of the reed frequency can be up to around 15% less than the peak Hp rpm.
This frequency is reduced by increasing the petal length or decreasing its thickness.
In EngMod you must be careful that the petals do not smash into the reed stops, as this causes easily seen erratic tip
lift from one cycle to the next.
You can still run the thin reeds but move the stops further way.
Intake length is easily seen in that at the rpm you want to tune for, the case pressure ( red ) goes negative at the same time the
carb / manifold / reed reflecting wave goes positive ( yellow ).
This helps open the reeds quickly, as the piston begins to rise.
If the engine 4 strokes in the top end with a reed change, this may signify that the air corrector isnt big enough, or that the main jet is simply too big.
But if the reed frequency is well above where it should be, then you may have a big mismatch with the intake tuning,that causes the jetting to go to hell as well.


Wobbly, Frits, Jan, we've been given figures for how much power the Aprilias were making at the peak of GP125. How much were the Honda's making?
They continued to use reed valves to the end on their factory bikes too right?

Would love to hear more about their engine development towards the end of the series life. We generally only hear about the 90's.


The Honda RS250 that was a full factory backed effort ( with several HRC and Showa technicians in the Team Scot tent ) in the last year of 250GP, I know finally for the first time had
almost normal length longer rods ( 109 I believe ) and the pipes were for sure fatter than had been used ( and published ) previously.
The engine was quicker than any previous effort, but was still down on power ( and thus top speed ) compared to the Aprilia.
It did however handle superbly, and the rider Aoyama, who subsequently achieved nothing of note on several GP machines, could cut good enough
lap times to be consistently at the front of the field.
Well meaning idiots back at the factory R&D dept had managed to slow down the Aprilia performance in comparison to Jans package, so that did nothing to help.
Sadly the Aprilia team riders detracted from each others efforts, and basically gave away the title to Honda by default.
If SuperSic had been in the field , I believe he would for sure have blitzed the title again.


did Honda crush Aoyama's RS? or have they moved away from doing that these days?


Looks like it's in the honda museum


https://www.youtube.com/watch?v=KnsDyg9XLdA


Wobbly, What direction did you decide was the best to rotate this disc in this situation?


The rotary valve could be spun either way in that case.
The engine sits with the crankshaft vertical ie rotated 90* anticlock to the pic, and the carb would be also vertically in line with that.
Thus as the slide opens it would flow along the manifold floor to the roof of the port - making no odds as to what side of the port was opening or closing.


Does anyone (Wob?) have dimensions of the mufflers for the 125 engines gp or karts? I remember there was one drawing here but was posted not on kiwibiker server and got lost.


All the GP bikes used mufflers with the perforated core a slip fit over the stinger tube OD.
The tuneability is gained in that mid power is enhanced if the perf is the same size as the stinger, top end is enhanced if the perf is slightly larger
for high speed tracks needing top speed, not acceleration.
In karts there is only 1 choice now - most stingers are around 26mm OD, and there has always been 2 choices of perf size.
The early versions were like GP ones where it slipped over the stinger, but later versions were developed with a 40mm core size.
The stinger U tube is around 300mm long and this, when dumped into the big core size makes hugely better overev power.
The first one I tried increased power at 14,000 by 15Hp,up to 40 from 25.
The newly homologated compulsory mufflers are slightly longer, but all have the big core as its alot quieter as well. so I have lost my advantage
in knowing that the bigger size was better as most used the smaller old version previously.


Wob, you mentioned some time ago to do a heat barrier coating on the piston crown and the bowl in the head. I know that the cart boys change their pistons more often than their pants.... So if it lasts for let's say 3 hours hard running, all is fine. But for a bike how long will that coating be durable, any experience?


The ceramic heat barrier coatings I have never seen or heard of it failing.
You only coat the piston in the bowl area, NOT in the squish band - same in the head.


Thank's Wob, got it. The squish needs to get rid of the heat, that's the reason not to coat, right?


The ceramic coating reflects the heat back to the gas boundary layer, this is fine in the chamber as it means more energy is used to create gas expansion.
But the boundary layer in the squish will detonate if the trapped end gases are heated by a hot surface ceramic layer.

[husaberg]

Silly question, (as you have likely posted it numerous times:scratch:) But how does the Ecotrons kit you are using, measure airflow Rob?


Not Rob, but it doesn´t.

The reason I asked is, conventional carbs do. (Well at least respond to it anyway.)

[Yow Ling]

The reason I asked is, conventional carbs do. (Well at least respond to it anyway.)

They estimate it from a table that considers rpm and throttle position , this is the alpha N thing, other methods are MAP and RPM, then some are able to run in a closed loop with lambda sensor some of the time and alpha n the rest of the time

[husaberg]

They estimate it from a table that considers rpm and throttle position , this is the alpha N thing, other methods are MAP and RPM, then some are able to run in a closed loop with lambda sensor some of the time and alpha n the rest of the time

Some also just use a airflow meter. I understand the concepts, I just wonder if TZ needs something a little more Sofishtickate'ed:yes:
cold wire, hot wire, flapper valve, plus some other ones that I can't spell so well:innocent:

[TZ350]

No ... I don't use an airflow meter nor is it very suitable for making the sort of short inlet tract needed for a high performance two stroke.

This is the way I understand it.

There are three common mapping methods. The MAF table, VE table and Alpha-N table and they can be mixed and matched. No map is perfect every where so at low throttle settings an ECU might use the VE map and then swap to the Alpha-N map at larger throttle openings. This mixing and matching can utilize several fueling maps. There can also be other maps, like required Lambda, ignition timing and power valve settings and cold start enrichment, injection end map Etc.

321223

The greatest changes in air flow occurs below 40% throttle opening and is where changes in air flow has the greatest definition and direct air flow measurement is most useful. Above 40% throttle, the changes in air flow are less well defined and throttle position gives better definition.

321229

The manifold air flow (MAF) table axis are RPM and physical weight of air (Load) as calculated from measured air flow and air temperature. The table is populated with the required Lambda values at each point.

When the ECU uses the weight of the measured air to calculate the required fuel to meet the mapped Lambda value specified and then uses an O2 sensor to see if it got it right, then this is a self correcting closed loop system.

321224

The axis of a volumetric efficiency (VE) table is manifold absolute pressure (MAP) and RPM. The map itself is populated with the Volumetric efficiency values of the engine for each point. The volumetric values are calculated (or estimated) from the dyno torque curves for that engine at various throttle settings.

321225

The axis of a Alpha-N map is the throttle position (TPS) and RPM. The map is populated with Load (anticipated actual combustion-able air) at each point. This "Load" is just a dimensionless number that does not relate to the actual weight of air trapped in the cylinder on the compression stroke, other than 120 indicates twice as much "Load" (trapped combustion-able air) as 60 does.

Because air flow in a two stroke inlet is so violently erratic mass air flow (MAF) and manifold absolute pressure (MAP) are not practical measurement methods so that leaves the Alpha-N approach of TPS and RPM with "Load" values for each point of the map.

321231 321232

To get started on developing a Alpha-N map, each "Load" of air value can only be more or less guessed at, maybe from riding the bike or dyno runs or simulated two stroke delivery ratios and the map Load values are then adjusted until things run successfully.

I am working with an Alpha-N map. Alpha-N is not supposed to be that great at low Load but pretty good at all out performance.

[Flettner]

It would be interesting to have a MAP "sampler", ie only measure air pressure between a certain crankshaft degrees when there is a useful pressure to measure. Turned off at all other parts of the cycle. I was going to try this but I could only do it with a mechanical method so didn't bother. There must be some electronic way to have the MAP sensor only take a reading when you tell it, not all the time?
And or intermix that information with a smoothed exhaust pressure.

[marsheng]

It would be interesting to have a MAP "sampler", ie only measure air pressure between a certain crankshaft degrees when there is a useful pressure to measure. Turned off at all other parts of the cycle. I was going to try this but I could only do it with a mechanical method so didn't bother. There must be some electronic way to have the MAP sensor only take a reading when you tell it, not all the time?
And or intermix that information with a smoothed exhaust pressure.

You measure the pressure over the full crank and then interpret the results from the data. The question is, does the MAP have the frequency response to follow the pressure changes ?

When in the manifold, it is measuring average.

Here is a fast one

http://www.omega.com/pptst/PX105.html

[nitro2tfx]

You measure the pressure over the full crank and then interpret the results from the data. The question is, does the MAP have the frequency response to follow the pressure changes ?

When in the manifold, it is measuring average.

Here is a fast one

http://www.omega.com/pptst/PX105.html



The equipment we have does exactly that and a whole lot more (combustion/intake/exhaust pressure tuning per degree), but it is for R&D and tuning (dyno or short races), not really something you would leave on the bike permanently as a control input.

The referenced Omega sensor is far too slow for per crank angle degree data.

[husaberg]

No ... I don't use an airflow meter nor is it very suitable for making the sort of short inlet tract needed for a high performance two stroke.

This is the way I understand it.

There are three common mapping methods. The MAF table, VE table and Alpha-N table and they can be mixed and matched. No map is perfect every where so at low throttle settings an ECU might use the VE map and then swap to the Alpha-N map at larger throttle openings. This mixing and matching can utilize several fueling maps. There can also be other maps, like required Lambda, ignition timing and power valve settings and cold start enrichment, injection end map Etc.

321223

The greatest changes in air flow occurs below 40% throttle opening and is where changes in air flow has the greatest definition and direct air flow measurement is most useful. Above 40% throttle, the changes in air flow are less well defined and throttle position gives better definition.

321229

The manifold air flow (MAF) table axis are RPM and physical weight of air (Load) as calculated from measured air flow and air temperature. The table is populated with the required Lambda values at each point.

When the ECU uses the weight of the measured air to calculate the required fuel to meet the mapped Lambda value specified and then uses an O2 sensor to see if it got it right, then this is a self correcting closed loop system.

321224

The axis of a volumetric efficiency (VE) table is manifold absolute pressure (MAP) and RPM. The map itself is populated with the Volumetric efficiency values of the engine for each point. The volumetric values are calculated (or estimated) from the dyno torque curves for that engine at various throttle settings.

321225

The axis of a Alpha-N map is the throttle position (TPS) and RPM. The map is populated with Load (anticipated actual combustion-able air) at each point. This "Load" is just a dimensionless number that does not relate to the actual weight of air trapped in the cylinder on the compression stroke, other than 120 indicates twice as much "Load" (trapped combustion-able air) as 60 does.

Because air flow in a two stroke inlet is so violently erratic mass air flow (MAF) and manifold absolute pressure (MAP) are not practical measurement methods so that leaves the Alpha-N approach of TPS and RPM with "Load" values for each point of the map.

321231 321232

To get started on developing a Alpha-N map, each "Load" of air value can only be more or less guessed at, maybe from riding the bike or dyno runs or simulated two stroke delivery ratios and the map Load values are then adjusted until things run successfully.

I am working with an Alpha-N map. Alpha-N is not supposed to be that great at low Load but pretty good at all out performance.
The kits seems to contain a MAP sensor, so I am confused.
http://www.ecotrons.com/products/2_stroke_small_engine_fuel_injection_kit/
I see they have a small electric oil pump available as well Rob
http://www.ecotrons.com/products/small_engine_rhb31_vz21_turbocharger/

[TZ350]

The kits seems to contain a MAP sensor, so I am confused.
http://www.ecotrons.com/products/2_stroke_small_engine_fuel_injection_kit/
I see they have a small electric oil pump available as well Rob
http://www.ecotrons.com/products/small_engine_rhb31_vz21_turbocharger/

The Ecotrons oil pump draws to much current for my limited system. The diaphragm pumper you suggested looks to be working Ok.

The basic kit was originally for 4T's running a VE and Alpha-N map. For 2T's the VE map is switched off and the MAP sensor and inlet temperature sensor are used by the CPU to correct for day to day RAD relative air density changes.

[Brett S]

The Walbro Wt-813 Carb used on 25cc r/c engines has an accelerator pump built in.
It has a flat on the throttle shaft which pushes the accelerator pump when opening throttle quickly.

[TZ350]

Spent an interesting evening talking with a guy who's name and number was given to me. He had built a turbocharged, alcohol burning fuel injected quad. Big hp and rideable, he suggested the issues with my bike must be somewhere in the sub maps that handle acceleration/deceleration and quite very possibly where the injector was positioned. It was an encouraging talk.

Also I never knew before how much power was really possible with a turbo 2T and alcohol, truly frightening. When I get the EFI thing sorted I will have to have a go at the turbo thing too ..... :eek:

So locally (in NZ) that I know of, there is a EFI YZ250 on petrol, and an air cooled Kawasaki BigHorn on E90 and the Turbo Quad on Alcohol. These all ran Ok, very rideable and throttled well, so there is hope for mine yet.

[mr bucketracer]

Spent an interesting evening talking with a guy who's name and number was given to me. He had built a turbocharged, alcohol burning fuel injected quad. Big hp and rideable, he suggested the issues with my bike must be somewhere in the sub maps that handle acceleration/deceleration and quite very possibly where the injector was positioned. It was an encouraging talk.

Also I never knew before how much power was really possible with a turbo 2T and alcohol, truly frightening. When I get the EFI thing sorted I will have to have a go at the turbo thing too ..... :eek:

So locally (in NZ) that I know of, there is a EFI YZ250 on petrol, and an air cooled Kawasaki BigHorn on E90 and the Turbo Quad on Alcohol. These all ran Ok, very rideable and throttled well, so there is hope for mine yet.hope the talk gets the project moveing the right way :niceone:

[ken seeber]

The human side of ESE. While Neil Lightbulb is over in Perth to participate in a National pylon event, we gave both Neil and son Carl a thrill in the STRIKE. Both are still alive. :sweatdrop

.321313

[ief]

fs1 problem fixed... in the virtual world that is (inlet tuning, inlet tuning and inlet tuning.... mostly) Had a lot of aha moments, always good.

But have 2 things I can't seem to solve myself. First, I made a pipe with ATAC and it gave 12% more power, that is with the latest beta, even with a wrong collector (bends where wrong) Anyone else noticed this or should I be aware of an easy to make mistake or?

Second is the membrane and resonant frequency. When modeling and measuring my tomos I noticed the membrane was way to stiff so I gave it some more free length, still way above what would be concidered ideal but in practice this didn't work at all, bike started '4stroking' at higher revs so my conclusion was that they didn't close fast enough. (though it could (could it?) be something else...)

edit: lol, something popped in my mind, inlet tuning? :D The pipe between carb and cilinder is pretty long on the tomos. (but still, engmod didn't show a problem as far as I am aware)

Any thoughts on that one?

[wobbly]

The 1st harmonic of the reed frequency can be up to around 15% less than the peak Hp rpm.
This frequency is reduced by increasing the petal length or decreasing its thickness.
In EngMod you must be careful that the petals do not smash into the reed stops, as this causes easily seen erratic tip
lift from one cycle to the next.
You can still run the thin reeds but move the stops further way.
Intake length is easily seen in that at the rpm you want to tune for, the case pressure ( red ) goes negative at the same time the
carb / manifold / reed reflecting wave goes positive ( yellow ).
This helps open the reeds quickly, as the piston begins to rise.
If the engine 4 strokes in the top end with a reed change, this may signify that the air corrector isnt big enough, or that the main jet is simply too big.
But if the reed frequency is well above where it should be, then you may have a big mismatch with the intake tuning,that causes the jetting to go to hell as well.

[lodgernz]

The rotary valve we will use in this new engine is made of carbon/kevlar so its inertia and out of balance is minimal - its even being made in the good ole USA.
Frits is right about the RV be it on the side or out the back - but using the sliding plate idea on the closing side of the inlet port gives a much better throttle connection
to enable easyer riding of an overpowered beast.
In fact Neal and I have discussed the next step to this design, being a pair of plates geared together that would close both sides of the port like a scissor blade action.
Thus equally reducing the open and close points simultaneously - and that leads onto the logical conclusion you could close the port altogether, deleting the throttle action within the carb or Injector.

I

Wobbly, What direction did you decide was the best to rotate this disc in this situation?

[chrisc]

Wobbly, Frits, Jan, we've been given figures for how much power the Aprilias were making at the peak of GP125. How much were the Honda's making?
They continued to use reed valves to the end on their factory bikes too right?

Would love to hear more about their engine development towards the end of the series life. We generally only hear about the 90's.

[ken seeber]

Could this be a handy thing?

http://www.mototrial.it/sostenitori/mototekna/novita-2013/testa-regolabile.htm

[lodgernz]

Could this be a handy thing?

http://www.mototrial.it/sostenitori/mototekna/novita-2013/testa-regolabile.htm

Would provide less than optimum squish clearance at all settings less than maximum compression, so benefits of lower com might be cancelled by reduced turbulence?

[husaberg]

Wobbly, Frits, Jan, we've been given figures for how much power the Aprilias were making at the peak of GP125. How much were the Honda's making?
They continued to use reed valves to the end on their factory bikes too right?

Would love to hear more about their engine development towards the end of the series life. We generally only hear about the 90's.

Frits has posted pics of their last kit pipes
IE same as KTM, pretty much I am picking so was the rest.
http://www.kiwibiker.co.nz/forums/album.php?albumid=4854&attachmentid=310144

[2T Institute]

Wobbly, What direction did you decide was the best to rotate this disc in this situation?

Clockwise port opening from the bottom up

[peewee]

Spent an interesting evening talking with a guy who's name and number was given to me. He had built a turbocharged, alcohol burning fuel injected quad. Big hp and rideable, he suggested the issues with my bike must be somewhere in the sub maps that handle acceleration/deceleration and quite very possibly where the injector was positioned. It was an encouraging talk.

Also I never knew before how much power was really possible with a turbo 2T and alcohol, truly frightening. When I get the EFI thing sorted I will have to have a go at the turbo thing too ..... :eek:

So locally (in NZ) that I know of, there is a EFI YZ250 on petrol, and an air cooled Kawasaki BigHorn on E90 and the Turbo Quad on Alcohol. These all ran Ok, very rideable and throttled well, so there is hope for mine yet.

did he happen to share any images of the methanol guzzling quad ? ive seen photos of backyard turbo 2t bikes but I don't think they ran long enough to get to the starting gate :laugh:

[TZ350]

did he happen to share any images of the methanol guzzling quad ? ive seen photos of backyard turbo 2t bikes but I don't think they ran long enough to get to the starting gate :laugh:

Yes ... true, and I would love to see some photos and more information too because it sounded like it was reasonably successful.

I was just a stranger with EFI problems ringing up unannounced for a chat. There was only so much I could ask for, but he did seem to understand the issues with 2T's and EFI. While we talked he downloaded the Ecotrons manual and quickly zeroed in on the area he thought would be profitable to explore. I left him with my email address and if he sends me any pictures, with his permission I will post them.

[Frits Overmars]

Wobbly, Frits, Jan, we've been given figures for how much power the Aprilias were making at the peak of GP125. How much were the Honda's making? They continued to use reed valves to the end on their factory bikes too right?
Would love to hear more about their engine development towards the end of the series life. We generally only hear about the 90's.I looked it up Chris: you joined the KiwiBiker forum three months before I did, so you may already have seen everything I could contribute, including these powercurves from the Aprilia RSW, the RSA and the reed-valve Derbi ridden by Jorge Lorenzo in 2004, I think it was.
Honda had already abandoned development of their 125 cc racers but Derbi-tuner Harald Bartol had carried on with his Honda-clones (the Derbi cylinders and pipes were exact Honda-copies). Bartols best result was 47,6 hp.
When Jan Thiel joined Derbi, he played a little with Bartol's inheritance and he managed to extract 49 hp out of the reed-valver before concentrating again on his own disc-valve engine.
321334

[wobbly]

The Honda RS250 that was a full factory backed effort ( with several HRC and Showa technicians in the Team Scot tent ) in the last year of 250GP, I know finally for the first time had
almost normal length longer rods ( 109 I believe ) and the pipes were for sure fatter than had been used ( and published ) previously.
The engine was quicker than any previous effort, but was still down on power ( and thus top speed ) compared to the Aprilia.
It did however handle superbly, and the rider Aoyama, who subsequently achieved nothing of note on several GP machines, could cut good enough
lap times to be consistently at the front of the field.
Well meaning idiots back at the factory R&D dept had managed to slow down the Aprilia performance in comparison to Jans package, so that did nothing to help.
Sadly the Aprilia team riders detracted from each others efforts, and basically gave away the title to Honda by default.
If SuperSic had been in the field , I believe he would for sure have blitzed the title again.

[crbbt]

did Honda crush Aoyama's RS? or have they moved away from doing that these days?

[Muciek]

did Honda crush Aoyama's RS? or have they moved away from doing that these days?
Looks like it's in the honda museum


https://www.youtube.com/watch?v=KnsDyg9XLdA

[wobbly]

The rotary valve could be spun either way in that case.
The engine sits with the crankshaft vertical ie rotated 90* anticlock to the pic, and the carb would be also vertically in line with that.
Thus as the slide opens it would flow along the manifold floor to the roof of the port - making no odds as to what side of the port was opening or closing.

[lodgernz]

The rotary valve could be spun either way in that case.
The engine sits with the crankshaft vertical ie rotated 90* anticlock to the pic, and the carb would be also vertically in line with that.
Thus as the slide opens it would flow along the manifold floor to the roof of the port - making no odds as to what side of the port was opening or closing.

Oh. I didn't expect that.
OK, if the crankshaft was horizontal as in the picture, and the carb consequently vertical, which way would you prefer to rotate the disc? Opening from the bottom up, i.e. clockwise?

[ief]

The 1st harmonic of the reed frequency can be up to around 15% less than the peak Hp rpm.
This frequency is reduced by increasing the petal length or decreasing its thickness.
In EngMod you must be careful that the petals do not smash into the reed stops, as this causes easily seen erratic tip
lift from one cycle to the next.
You can still run the thin reeds but move the stops further way.
Intake length is easily seen in that at the rpm you want to tune for, the case pressure ( red ) goes negative at the same time the
carb / manifold / reed reflecting wave goes positive ( yellow ).
This helps open the reeds quickly, as the piston begins to rise.
If the engine 4 strokes in the top end with a reed change, this may signify that the air corrector isnt big enough, or that the main jet is simply too big.
But if the reed frequency is well above where it should be, then you may have a big mismatch with the intake tuning,that causes the jetting to go to hell as well.

Wob, you're golden. Had to digest but I think I figured it out now, tnx!!! None of the above seems at play but my presumption of it being double dipping was just wrong... And my 'main ride' has just the situation to test this I think.

[Muciek]

Does anyone (Wob?) have dimensions of the mufflers for the 125 engines gp or karts? I remember there was one drawing here but was posted not on kiwibiker server and got lost.

[wobbly]

All the GP bikes used mufflers with the perforated core a slip fit over the stinger tube OD.
The tuneability is gained in that mid power is enhanced if the perf is the same size as the stinger, top end is enhanced if the perf is slightly larger
for high speed tracks needing top speed, not acceleration.
In karts there is only 1 choice now - most stingers are around 26mm OD, and there has always been 2 choices of perf size.
The early versions were like GP ones where it slipped over the stinger, but later versions were developed with a 40mm core size.
The stinger U tube is around 300mm long and this, when dumped into the big core size makes hugely better overev power.
The first one I tried increased power at 14,000 by 15Hp,up to 40 from 25.
The newly homologated compulsory mufflers are slightly longer, but all have the big core as its alot quieter as well. so I have lost my advantage
in knowing that the bigger size was better as most used the smaller old version previously.

[41juergen]

Wob, you mentioned some time ago to do a heat barrier coating on the piston crown and the bowl in the head. I know that the cart boys change their pistons more often than their pants.... So if it lasts for let's say 3 hours hard running, all is fine. But for a bike how long will that coating be durable, any experience?

[wobbly]

The ceramic heat barrier coatings I have never seen or heard of it failing.
You only coat the piston in the bowl area, NOT in the squish band - same in the head.

[oldjohnno]

Wow, I've spent the last few days wading through this thread and it really is a wealth of information. To Frits, Wob and all the others, thank you.

Now to my questions; they may well be off-topic and if so I'm happy to take them somewhere more appropriate if someone could point me there. I'm a long-time Bultaco tragic - hardly 2t state of the art I know but I like them and the've served me well and I enjoy the challenges involved in improving inherently flawed designs.

My current project is a Metralla GT with a modified 370cc Pursang engine - Blair based porting, YZ250 reed with rear transfer, Husky 390 head etc. I've just finished building a dyno and should have some power figures in the next day or so. What I'd like to do is run it at Lake Gairdner next year, and with a little work I could possibly run it as a MPF and MPSF (modified production and modified production partially streamlined) in both 350 and 500 classes. Fuel would be methanol as I just don't envisage the air cooled engine surviving for that long at WOT on petrol.

I fully realise that this engine will be severely limited in output compared to modern designs - it's quite oversquare (85x64) which limits available port area with a single exhaust port, four transfers plus the rear, and air cooled. But on the other hand they're a very small, narrow bike with little frontal area, and previous speed attempts on similar machines have shown that they can reach remarkable speeds with quite modest engine outputs. The current records aren't particularly high so I'm not entirely convinced yet that I'm wasting my time... But before I commit I plan to spend as much time on the brake as necessary to prove that it's capable of making the necessary power as well as able to resist melting down at prolonged WOT.

My half-baked plan at this stage is see if a reasonable amount of power (65hp?) can be made with the Bul top end. Failing that I've been looking at some similarly sized but more modern cylinders that could possibly be adapted. One in particular that interests me would be from the Arctic Cat 800 HO engine - an 800 twin that makes 165hp at moderate rpms.

Anyhow I'd welcome advice anyone may have on developing such an engine with limited wall area as well as transfer passages that hug the walls fairly closely. I'm also interested in anything on methanol usage, particularly with regard to temperature control in an air cooled big bore engine. As well, I'm thinking of buying an EngMod2t license - does it model old-style engines such as the Bul effectively?

Here is the bike in question:

[TZ350]

I'm a long-time Bultaco tragic - hardly 2t state of the art I know but I like them and they've served me well and I enjoy the challenges involved in improving inherently flawed designs.

Totally in the right place for that, I love your bike, please keep posting as your project progresses.

[husaberg]

Wow, I've spent the last few days wading through this thread and it really is a wealth of information. To Frits, Wob and all the others, thank you.

Now to my questions; they may well be off-topic and if so I'm happy to take them somewhere more appropriate if someone could point me there. I'm a long-time Bultaco tragic - hardly 2t state of the art I know but I like them and the've served me well and I enjoy the challenges involved in improving inherently flawed designs.

My current project is a Metralla GT with a modified 370cc Pursang engine - Blair based porting, YZ250 reed with rear transfer, Husky 390 head etc. I've just finished building a dyno and should have some power figures in the next day or so. What I'd like to do is run it at Lake Gairdner next year, and with a little work I could possibly run it as a MPF and MPSF (modified production and modified production partially streamlined) in both 350 and 500 classes. Fuel would be methanol as I just don't envisage the air cooled engine surviving for that long at WOT on petrol.

I fully realise that this engine will be severely limited in output compared to modern designs - it's quite oversquare (85x64) which limits available port area with a single exhaust port, four transfers plus the rear, and air cooled. But on the other hand they're a very small, narrow bike with little frontal area, and previous speed attempts on similar machines have shown that they can reach remarkable speeds with quite modest engine outputs. The current records aren't particularly high so I'm not entirely convinced yet that I'm wasting my time... But before I commit I plan to spend as much time on the brake as necessary to prove that it's capable of making the necessary power as well as able to resist melting down at prolonged WOT.

My half-baked plan at this stage is see if a reasonable amount of power (65hp?) can be made with the Bul top end. Failing that I've been looking at some similarly sized but more modern cylinders that could possibly be adapted. One in particular that interests me would be from the Arctic Cat 800 HO engine - an 800 twin that makes 165hp at moderate rpms.

Anyhow I'd welcome advice anyone may have on developing such an engine with limited wall area as well as transfer passages that hug the walls fairly closely. I'm also interested in anything on methanol usage, particularly with regard to temperature control in an air cooled big bore engine. As well, I'm thinking of buying an EngMod2t license - does it model old-style engines such as the Bul effectively?

Here is the bike in question:

I have always loved the Metralla.
Bert Flood used to prep them back in the day and they were hugely succesfull along with the 360s
But you likely already knew that anyway.
321395321396

[wobbly]

An air cooled on Meth operates very similar performance wise to a water cooled on petrol, so its a match in heaven.
In fact if its done really well,you can exceed the bmep of a watercooled on good octane fuel, due to the jungle juices very high latent heat of evaporation - and not suffer the usual issues of heat induced power fade.
EngMod will model anything well, it all depends upon the input accuracy, so yes your crap transfer duct geometry is fully accounted for as an input variable.
As you have a dyno you can convert the power figures to crank easy enough, and from the peak Hp rpm you actually see, you can then modify the pipe temp
numbers of that setup, as modeled, to get accurate outputs for future improvements in port or pipe designs.

[oldjohnno]

An air cooled on Meth operates very similar performance wise to a water cooled on petrol, so its a match in heaven.
In fact if its done really well,you can exceed the bmep of a watercooled on good octane fuel, due to the jungle juices very high latent heat of evaporation - and not suffer the usual issues of heat induced power fade.
EngMod will model anything well, it all depends upon the input accuracy, so yes your crap transfer duct geometry is fully accounted for as an input variable.
As you have a dyno you can convert the power figures to crank easy enough, and from the peak Hp rpm you actually see, you can then modify the pipe temp
numbers of that setup, as modeled, to get accurate outputs for future improvements in port or pipe designs.

Thanks for that Wob, very helpful. Does it ever get to the point where it overcools and make consistent jetting difficult? I had one engine that in effect had two-speed jet requirements - up to a certain head temperature it wanted a particular jet and timing figure, then beyond that it was like a toggle switch had been flicked and it wanted something else entirely. I'm thinking about running on salt where the first mile or so is basically the warmup, and whether it'll be hard to run cleanly and safely over a wide temp range. I guess I could run a manual powerjet control and adjust according to EGT?

Is it an advantage to run something like a Lectron with meth? Supposedly they emit a finer droplet size than say a Mik. but I don't know if this is true. But if it is perhaps it would help take advantage of the high LHV..

Husaberg and TZ350, thanks for the warm welcome. Bert Flood set some records in the 70s on both his 360 drag bike and a 125 streamliner he built. The 360 did 152mph (and incidentally did low 12s on the strip) while the 125 could only manage 115. I find Berts 360 speed encouraging, as well as the performance of the old 360 endurance racer that won Montjuic. This bike was very similar to mine, mildly tuned to last 24hrs and unfaired, yet still would pull around 135mph. All this was a long time ago, and without wanting to detract from Berts or anyone elses efforts they didn't have access to the tools and knowledge we benefit from today, so I think we could reasonably expect to improve on those speeds.

[TZ350]

Does it ever get to the point where it overcools and make consistent jetting difficult?

Sure can, not difficult, impossible as the motor can run so cold that the Methanol does not completely evaporate and the engine runs lean. Any more Methanol fuel to richen things up only makes the engine run colder and leaner. You can get to the point where there is raw Methanol dribbling out the exhaust and the motor is still running lean, been there done that.

I had a Suzuki road racer fitted with RD barrels that ran methanol and the trick was to blend the fuel so that the engine temperature was high enough to evaporate all the fuel. For my RD/Suzuki the ideal blend was 50/50 Acetone Methanol, I expect that other motors may require something different so you will have to experiment but 50/50 is a good place to start.

Acetone has a higher octane rating than Methanol, evaporates better, a latent heat of evaporation about half way between petrol and Methanol and Acetone significantly reduces Methanols tendency to detonation when lean and Acetone very much helps keep oil in suspension in Methanol blends. Current unleaded pump fuel seems to blend with Methanol so probably worth a try. Sit a sample of mixed fuel in a glass jar for a few days to see if it separates out.

Use Yamabond on the cases, the only issue I had was oil seals, some coped with Acetone others did not. Suzuki crank oil seals worked best, Yamaha Teflon lipped seals swelled up and were useless. Test the seals you are going to use in a glass of fuel for several days. After a days racing I used to run a petrol mix very rich in oil through the motor to clean out the hydroscopic Methanol mix so that the crank did not rust. The richer in oil the petrol/oil mix can be the better the petrol will run with the Alcohol jetting.

[wobbly]

The way to ensure that you dont get the issue that TeeZee describes is to run as high com as you can,and then tune to achieve reasonable egt numbers.
The optimum com-egt is easy enough to dial in on a dyno - but without the egt telling you what is going on then you are working in the dark.
Methanol will run very rich with no power loss,but if you choose say 850* as a baseline and jet to get that, then go up in com and rejet to again get that same egt
the power generated will tell you if you are on the right path or not.
Lectrons do have very very good atomization from the flat needle, but the powerjet nozzles are no better than a normal carb.
Thus you need to run as rich as you can on the needle and just fine tune with small powerjets.
This can be helped alot by cutting the nozzle exit at 45* facing downstream, and then drill a small 0.15mm hole in the front side about 5mm up from the end.
The other trick is to run twin powerjets and rpm switch one with an inline solenoid,thus getting the rich mixture needed at peak power, then leaning off over the top of the pipe.

[F5 Dave]

If you have egt and not running an ignitech, then an intelejet adjustable pj might be a good idea for high speed runs do you think Wob?

[wobbly]

The PJ with built in air correction that is used to adjust the fuel flow is probably going to have better emulsified droplets
than a simple screw adjusted one.
But I havnt used one yet.
I have a couple here and will test them on the new 400 Superlight I am building for Charlett.

[Sketchy_Racer]

I have a couple here and will test them on the new 400 Superlight I am building for Charlett.

Ah fuck off, how am I to burgle the Superlite class if Dennis turns up on a 400! :baby:

Although that will make 5 fast two strokes that I know of that are being preped for superlite at the moment, not to mention that Jason Eastons bike is getting a new exhaust made up so perhaps he's looking at coming out of the woodwork and schooling us all. Superlite might be the class to be in/watch this season!!

[wobbly]

Taking the Superlight title would be easy enough.
You need to just find 20 Hp, drop 20Kg, brake 3 lengths later into every corner,then ride like Freddie.
Get just 2 of those 4 right and you stand 1/2 a chance.
Trouble is Dennis is into the 13's at Hampton with a Pre 82 spec 400,add 100mm to the swingarm,add slicks,USDs and radial 4 pots
then I reckon a 10 is gonna be easy also.

[41juergen]

The ceramic heat barrier coatings I have never seen or heard of it failing.
You only coat the piston in the bowl area, NOT in the squish band - same in the head.

Thank's Wob, got it. The squish needs to get rid of the heat, that's the reason not to coat, right?

[wobbly]

The ceramic coating reflects the heat back to the gas boundary layer, this is fine in the chamber as it means more energy is used to create gas expansion.
But the boundary layer in the squish will detonate if the trapped end gases are heated by a hot surface ceramic coating.

[F5 Dave]

So Wob, who's this guy? Saw an earlier article and thought it sounded like a hard sell.

http://www.stuff.co.nz/motoring/79517529/dennis-lawson--the-kiwi-who-is-cleaning-up-the-twostroke

[Lef16]

Hey wob,
I've got a problem with knock gauge here.
I bought it from ebay and I bought a Bosch knock sensor for Peugeot or Citroen.
Yesterdat I wired it up and tested it.
When I give 12V to it one or two green lights give a strong flash and after a moment only one green light is on.I tried to hit with a plastic hammer but nothing changer,not even 2nd green light flashed.I tried to change the sensivity but nothing changes.
When I un-connect(sorry for my english :P ) the sensor with the gauge and touch gauge's red wire with bare hand 2nd green or maybe red too lights with a strong light again for a moment.
Is this normal?
Cheers

[bjorn.clauw.1]

Hey wob,
I've got a problem with knock gauge here.
I bought it from ebay and I bought a Bosch knock sensor for Peugeot or Citroen.
Yesterdat I wired it up and tested it.
When I give 12V to it one or two green lights give a strong flash and after a moment only one green light is on.I tried to hit with a plastic hammer but nothing changer,not even 2nd green light flashed.I tried to change the sensivity but nothing changes.
When I un-connect(sorry for my english :P ) the sensor with the gauge and touch gauge's red wire with bare hand 2nd green or maybe red too lights with a strong light again for a moment.
Is this normal?
Cheers

Installed mine last week. Bosch nr 0 261 231188. Hitting it with something plastic doesn't work. Needs to be metal (gently tapping the bolt with a spanner works for me).

[wobbly]

One green led tells you its running, and yes if you tap the mounting bolt with a steel hammer another couple of lights should flash.
A firm crack from the hammer will show the deto led.
Actual deto is just like hitting the piston with a steel hammer - this is why the head or cylinder nuts can be loosened when it happens.
You can adjust the sensitivity with the engine running so that under acceleration all the lights flicker except the deto led.
The 0-5V output works real well on a datalogger,as I can read the voltage level to the point of seeing a few 5V spikes
with every speedshifted gearchange - so anything approaching real deto at any rpm/throttle position is dead obvious.

Re the so called guru Denver - I worked with him in China on the Mira engine project, and all I will say is that I am guessing he would now be one of the reasons
the original Martin investor/inventor has walked away, wanting his name removed.
A previous misinformed media blurb tried erroneously to compare Den to John Britten,the problem being that most of Johns ideas were based on practical innovations, and were able to be ( and were ) translated into
working hardware by people with the requisite skills.
Denvers skill set revolves in large part, in being able to convince everyone, including himself - that anything he has thought up,that really is completely off the wall, is actually the next best thing to sliced bread.
This is then quickly followed by someone else's cash being vigorously poured down a very deep hole.
A perfect example would be the zillion hours spent designing a 1000cc V twin 2T, with no regard at all to the obvious fact a CR500 has real problems fitting 1 pipe on the bike - try finding room for 2 of them.
He is totally sincere and honest in his endevours ,but is one of those cases of excessive intellect that simply cant see real world limitations being a hindrance.

[nitro2tfx]

A little off topic, does anyone know where to find stock port timing (and possibly stock port dimensions too) for a Banshee engine, as well as length/diameter dimensions for a Toomey T6 exhaust (for a Banshee) ? It seems there are so many aftermarket parts for Banshees that everybody just buys bolt-on parts and goes riding, without actually knowing much of anything about specifics, at least that is my impression. Eventually I might be able to post some actual pressure traces for the Banshee engine on here, as well as for whatever mods end up being applied to it, so it's not just a one sided request LOL. Thanks.

[peewee]

to have any success with engmod youll need to know more than just window timing. a dummy engine can be pieced together with junk parts from ebay for peanuts then youll have all the info you can shake a stick at. I wouldn't bother with Toomey if you want a high performance pipe

[Lef16]

You can adjust the sensitivity with the engine running so that under acceleration all the lights flicker except the deto led.
All lights except deto led?
Do you meen the 2 "normal condition" green led's should flicker with engine running,or caution and preignition light's should flicker too?

[nitro2tfx]

to have any success with engmod youll need to know more than just window timing. a dummy engine can be pieced together with junk parts from ebay for peanuts then youll have all the info you can shake a stick at. I wouldn't bother with Toomey if you want a high performance pipe

No Engmod, this would be done using the real McCoy, pressure sensors, though Neels would probably want to give it a spin through Engmod to compare the simulated data to the actual data.

The engine currently exists with a T6 Toomey and stock cylinders, that is not what it will end up being, I was simply planning to present the pressure data for the as is engine first, so all that is needed to do that properly is the port timing, bore, stroke, con rod length, piston pin offset, compression ratio, and of course the instrumentation.

If Neels wants to run it through Engmod then yes a lot more about the engine would need to be known, such as the dimensions of the T6 pipe, reeds, etc. etc. etc.

[41juergen]

The ceramic coating reflects the heat back to the gas boundary layer, this is fine in the chamber as it means more energy is used to create gas expansion.
But the boundary layer in the squish will detonate if the trapped end gases are heated by a hot surface ceramic coating.

Yeep, got it. I got already a quote from Chris from HPC, but still need to wait for the inserts...

[ief]

No Engmod, this would be done using the real McCoy, pressure sensors, though Neels would probably want to give it a spin through Engmod to compare the simulated data to the actual data.

The engine currently exists with a T6 Toomey and stock cylinders, that is not what it will end up being, I was simply planning to present the pressure data for the as is engine first, so all that is needed to do that properly is the port timing, bore, stroke, con rod length, piston pin offset, compression ratio, and of course the instrumentation.

If Neels wants to run it through Engmod then yes a lot more about the engine would need to be known, such as the dimensions of the T6 pipe, reeds, etc. etc. etc.

Not sure what you're asking, so you have the pipes? The rz file can easilly be converted to banshee, loose the pv and change port timing. If you suplied pipe dimentions... or whip something up that produces the same curve prolly not that hard to do.

[nitro2tfx]

Not sure what you're asking, so you have the pipes? The rz file can easilly be converted to banshee, loose the pv and change port timing. If you suplied pipe dimentions... or whip something up that produces the same curve prolly not that hard to do.

To clarify, I don't have Engmod, nor am I looking to get Engmod.

A friend of mine has a Banshee, T6 Toomey pipe, stock cylinders, VF4 reeds. I thought it might be interesting to simply install some pressure sensors on the engine sometime when I'm over there, and post the data on here (perhaps a new thread) for discussion. If and when mods are made to the engine I would post some more data.

This is not simulated data, but real data, and likely Neels would eventually want to run Engmod on it to compare the simulated results to the real results.

All I am asking for, for the time being, is what the stock port timing is for a Banshee, which from another website is indicated as 185 exhaust, 120 transfer, 114 boost and 110mm con rod, but I have no idea if this is correct or just speculation.

[Vannik]

Gentlemen,

Nitro2tfx is way too modest - he produces and sells some of the best and best value for money engine measuring equipment. Have a look at:

http://tfxengine.com/index.html

[ief]

Most strange indeed that there ain't a portmap floating around somewhere. Seen the same stuff you have I guess so that's no help. Somehow I have 169 exhaust in my head but anyway's... Surely someone on here has a barrel laying around. As for the pipe perhaps your friend could measure it is what I meant.

[wobbly]

If you adjust the sensitivity so that the pre deto light just flickers occasionally when under hard full load acceleration, then you know for sure
that as soon as a real "knock " event occurs the deto led will light up instantly.

[2T Institute]

My current project is a Metralla GT with a modified 370cc Pursang engine - Blair based porting, YZ250 reed with rear transfer, Husky 390 head etc. I've just finished building a dyno and should have some power figures in the next day or so. What I'd like to do is run it at Lake Gairdner next year, and with a little work I could possibly run it as a MPF and MPSF (modified production and modified production partially streamlined) in both 350 and 500 classes. Fuel would be methanol as I just don't envisage the air cooled engine surviving for that long at WOT on petrol.

I fully realise that this engine will be severely limited in output compared to modern designs - it's quite oversquare (85x64) which limits available port area with a single exhaust port, four transfers plus the rear, and air cooled. But on the other hand they're a very small, narrow bike with little frontal area, and previous speed attempts on similar machines have shown that they can reach remarkable speeds with quite modest engine outputs. The current records aren't particularly high so I'm not entirely convinced yet that I'm wasting my time... But before I commit I plan to spend as much time on the brake as necessary to prove that it's capable of making the necessary power as well as able to resist melting down at prolonged WOT.



Don't get sucked in by the low numbers from Lake Gardiner it isn't El Mirage or Bonneville, the task is much harder than you envisage, which will become apparent when you get out there. Don't worry so much about hotting the engine up, you will have enough dramas tuning the engine with the conditions you are likely to encounter. The big hurdles you have to jump are first timers need to be licenced to shoot for a record, next is your not allowed to work on a vehicle outside your designated pit (you might be in the line up at 8.30 am and run at 1pm), ambient temp could be anywhere from 20*C to 48*C, its in the middle of nowhere if you have a drama and you can't fix it then there is your week over and the increasing popularity of the event means you get less run time generally 1 or 2 a day if your lucky. Then the sting in the tail come 6 months later when every bit of aluminium is still growing "fur" on it despite cleaning it every month. Beware it's highly addictive because of the scale of the challenge. Run low comp and be able to predict jetting for the weather your likely to encounter at the time of your run.

[oldjohnno]

Don't get sucked in by the low numbers from Lake Gardiner it isn't El Mirage or Bonneville, the task is much harder than you envisage, which will become apparent when you get out there. Don't worry so much about hotting the engine up, you will have enough dramas tuning the engine with the conditions you are likely to encounter. The big hurdles you have to jump are first timers need to be licenced to shoot for a record, next is your not allowed to work on a vehicle outside your designated pit (you might be in the line up at 8.30 am and run at 1pm), ambient temp could be anywhere from 20*C to 48*C, its in the middle of nowhere if you have a drama and you can't fix it then there is your week over and the increasing popularity of the event means you get less run time generally 1 or 2 a day if your lucky. Then the sting in the tail come 6 months later when every bit of aluminium is still growing "fur" on it despite cleaning it every month. Beware it's highly addictive because of the scale of the challenge. Run low comp and be able to predict jetting for the weather your likely to encounter at the time of your run.

That is EXACTLY the sort of practical advice I need, thank you! Please, if anything else comes to mind that you think might help I'd appreciate hearing about it, either here or via PM. There's another bloke in my home town who has been running successfully at LG for the last couple of years, but in a completely different class. I'm hoping that he may also help us - and I'm happy to supply the beer - to turn up reasonably well prepared.

Re jetting to suit the conditions - will working on air RAD get in the ballpark or is something more sophisticated required?

[ken seeber]

Re the so called guru Denver - I worked with him in China on the Mira engine project, and all I will say is that I am guessing he would now be one of the reasons
the original Martin investor/inventor has walked away, wanting his name removed.
A previous misinformed media blurb tried erroneously to compare Den to John Britten,the problem being that most of Johns ideas were based on practical innovations, and were able to be ( and were ) translated into
working hardware by people with the requisite skills.
Denvers skill set revolves in large part, in being able to convince everyone, including himself - that anything he has thought up,that really is completely off the wall, is actually the next best thing to sliced bread.
This is then quickly followed by someone else's cash being vigorously poured down a very deep hole.
A perfect example would be the zillion hours spent designing a 1000cc V twin 2T, with no regard at all to the obvious fact a CR500 has real problems fitting 1 pipe on the bike - try finding room for 2 of them.
He is totally sincere and honest in his endevours ,but is one of those cases of excessive intellect that simply cant see real world limitations being a hindrance.

Wobbly, exceptionally well written. If 2 strokes don't need to go any faster, you could be come a journo. :2thumbsup

[Makr]

My current project is a Metralla GT with a modified 370cc Pursang engine - Blair based porting, YZ250 reed with rear transfer, Husky 390 head etc. I've just finished building a dyno and should have some power figures in the next day or so. What I'd like to do is run it at Lake Gairdner next year, and with a little work I could possibly run it as a MPF and MPSF (modified production and modified production partially streamlined) in both 350 and 500 classes. Fuel would be methanol as I just don't envisage the air cooled engine surviving for that long at WOT on petrol.

I fully realise that this engine will be severely limited in output compared to modern designs - it's quite oversquare (85x64) which limits available port area with a single exhaust port, four transfers plus the rear, and air cooled. But on the other hand they're a very small, narrow bike with little frontal area, and previous speed attempts on similar machines have shown that they can reach remarkable speeds with quite modest engine outputs. The current records aren't particularly high so I'm not entirely convinced yet that I'm wasting my time... But before I commit I plan to spend as much time on the brake as necessary to prove that it's capable of making the necessary power as well as able to resist melting down at prolonged WOT.

My half-baked plan at this stage is see if a reasonable amount of power (65hp?) can be made with the Bul top end. Failing that I've been looking at some similarly sized but more modern cylinders that could possibly be adapted. One in particular that interests me would be from the Arctic Cat 800 HO engine - an 800 twin that makes 165hp at moderate rpms.

Anyhow I'd welcome advice anyone may have on developing such an engine with limited wall area as well as transfer passages that hug the walls fairly closely. I'm also interested in anything on methanol usage, particularly with regard to temperature control in an air cooled big bore engine. As well, I'm thinking of buying an EngMod2t license - does it model old-style engines such as the Bul effectively?

Here is the bike in question:

I love Bultacos.

I have never been to LG, but have raced at Bonneville for many years. 2T Institute is right about landspeed records. They are cherished because they are way harder than people realize, and LG is especially so.

I tried, for years, to make an air cooled RD400 last on gas...it really never did. Wobbly posted somewhere he experimented with methanol and WOT with an aircooled engine, loaded, and was successful with it. I never ran anything but gas because that was the record I was after. The final year I ran with the air cooled engine I had a ten orifice water mister, like that used in vintage airplane racing, that sprayed the front of the engine. It almost made it. Some clever ducting might have pulled it off, but a water cooled cylinder was really the solution.

If you do switch cylinders, go water cooled and save yourself much grief. WOT in top gear for miles is not done in any other motorsport. You just can't transfer enough heat into the air. You have a tiny window of time to sort out a huge amount of problems, and it is tough to test anywhere else. Good luck!

[oldjohnno]

The current edition of Old Bike Australasia magazine has a great story on the late Bert Flood. It mentions Berts speed attempts on his 350 Bul drag bike in '76, when he ran 152 on a closed-off section of the Northern Highway. Apparently he seized on the first run and had to do a hasty roadside rebuild before backing it up. Some good photos too, I'll put a couple up later.

I wouldn't even try to run petrol on the lake; it'd almost certainly end in tears.

[Peter1962]

Finally, there is a company that is gonna release an MX engine 250 cc 66,4 x 72 mm (+ kit 72 x 72 mm so 300 cc) with a balancer. Husky is using KTM engines so they probably are going to do exactly the same thing in 2017.
Should be a good engine for karting in the British national series for mono 250cc. (the competition is mainly the WIWA version of the Gas Gas 250 which has also a balance shaft.
http://www.vitalmx.com/photos/features/First-Look-2017-Husqvarna-Motocross-Models,38830/2017-Husqvarna-TC-250,91990/ML512,13480

[nitro2tfx]

Gentlemen,

Nitro2tfx is way too modest - he produces and sells some of the best and best value for money engine measuring equipment. Have a look at:

http://tfxengine.com/index.html


Thanks for the intro Neels. As you know a Banshee engine is not exactly state of the art, but all the customer data we have from 2 strokes in general that are at the high levels of development, is confidential, so I can't ever post any of that.

There is no great agenda related to instrumenting a friend's Banshee engine, other than it is handy and it is a popular engine with a sizeable aftermarket/following. I suspect a Banshee has probably never been instrumented with pressure sensors before, or at least data for such has never been made available to the public.

The Banshee engine, even with future bolt-on aftermarket mods is likely to still show up as being a relative disaster in terms of combustion pressure, intake, transfer and exhaust port pressures, in that as it currently stands the engine probably only has an IMEP of 120 psi at peak HP (just a guess but we shall see), so pressure magnitudes in the combustion chamber, intake, crankcase, and exhaust are going to be pretty lame and probably ill timed as well. It seems likely that there could be a couple relatively simple things that come from this exercise that could be turned into aftermarket Banshee products that currently do not exist.

[nitro2tfx]

Most strange indeed that there ain't a portmap floating around somewhere. Seen the same stuff you have I guess so that's no help. Somehow I have 169 exhaust in my head but anyway's... Surely someone on here has a barrel laying around. As for the pipe perhaps your friend could measure it is what I meant.

Unfortunately the T6 pipe has no distinct cones, it can be measured by hand, but it will be a PITA. The pipe dimensions are not needed to collect or process the data, but it's always good to know the dimensions in one's head when looking at a trace.

For an engine that has a substantial aftermarket/following there is exceedingly little detailed info popping up on my searches, it seems to be primarily a bolt-on market for that engine.

[jonny quest]

Which knock gauge are you guys buying?

I saw a Kite Gizmo cylindrical shaped gauge that is self adjusting to your engines frequency by running engine, and holding a button down for a few seconds.

[ief]

It's out there, or better said, I'm pretty confidant this is correct:

link to post (http://bansheehq.com/forums/index.php?/topic/132925-exhaust-port-height-porting-question/#entry1147898)

Gives a timing of:

Exhaust duration: 187.4
Transfer duration: 114.4
Blowdown duration: 36.5


I don't think stock banshee has staggered ports though they where build pretty long and perhaps in different flavors like the rz.

If you like I could play with a rz pack file i have and turn it into the banshee and see if I can get a curve out of it resembling the curve published for the Tr6 exhaust... guestimating the exhaust by eye and think I know could be a starting point. Just not sure if that effort will be considered 'close enough' :) Other difference is the reed and ignition but guess that's it, engine wise.

[wobbly]

The Banshee and the RZ do have ( wierd ) stagger, but as always the issue is that most height dimensions are taken from the deck.
But what is the deck clearance to the timing edge at TDC.
Its the same problem we have with the Merican way of quoting head cc - this is given as a volume on a flat plate - with no reference to deck height or dome volume
so it has no meaning at all.
The only number I can find that I would take as gospel is from an old TSR sample file, it has the stock Ex open at 89.48* = 181.04 Duration, but in Toms file he
has "corrected " the transfers, so I cant confirm yet what the real transfer durations are.

[wobbly]

Here is the link to the kock gauge - you can order with a grounding output to trigger an Ignitech retard function and/or
a 0-5V output for a datalogger.
This really is the best thing since sliced bread.
Its cheap,and works perfectly.

http://www.ebay.com/itm/Knock-gauge-for-detonation-sensor-klopfsensor-NEW-with-output-/111623836064

[ief]

The Banshee and the RZ do have ( wierd ) stagger, but as always the issue is that most height dimensions are taken from the deck.

For rz only from 1986 on.

Not to be a smartarse but if we go like that then there ain't 'a' portiming for the stock banshee since there alway's a little variation.

But true, we have to factor in deckhight, say something like 0.8 for an rz so banshee as wel makes:

Exhaust duration: 184.9
Transfer duration: 119.0
Blowdown duration: 33.0



Gotta start somewhere right.

[chrisc]

Aprilia RSV1000 with a V4 500cc 2 stroke engine. Cylinders from a kart engine, rest made by this dude Cristian Polverelli for his own personal amusement. What an awesome project.

http://2tiemposracing.com/blog/cristian-polverelli-500/

http://2tiemposracing.com/blog/wp-content/uploads/2016/05/polverelli_test_misano-10.jpg

Google translated:

Cristian Polverelli and artisan 500cc.

While we are talking about the construction by the world-renowned international manufacturer and Suter, with its MMX 500cc.

But someone has been able to do the same, with far fewer resources and less time. They are not only large industries can perform miracles.

Cristian Polverelli has managed to build something really special, it has built a 500cc 4-cylinder 2-stroke; but he has done something even bigger and is not palpable. It has provided data to build 500cc engines with really economic costs and far from what people may think of the cost of a 500cc.polverelli_test_misano-10

What prompted Cristian to carry out such a difficult project? Just passion, which stands as the basis of motorcycling :. "I am 41 years old, I grew up in the age of 125 2 times when I have learned to tune their engines as RGV 250, I felt that I was missing a motorcycle as well. 4 times street are fine, but wanted to use bikes 2 times. I love the "back" of the 500 2-stroke, 4 escapes, I want to see the faces of those coming from behind. "Achieving this has taken me much time and effort I started the project in 2010, although the bike in my head I quickly finished, the problem was that my head wanted to make all his pieces by hand. I worked on it during my free time. " Cristian has worked hard to achieve his dream, and most of the bike was made with his own hands, as the crankcase pressure sand or crankshaft. The chassis and swingarm are Aprilia RSV 1000, while the change is an MV Agusta F4, the engine has been built around these parts. Could have done cylinders, but implied increase my budget and extend the project too, he decided to use four-cylinder Seven, firm specializing in karting.polverelli_test_misano-1

A bike that could have reduced construction time pieces already made, but Cristian decided that the road would be adapted to their possibilities, a craftsman and delicate work that certainly would be really satisfying for the protagonist.

"I have not done for indecent exposure," he continues Cristian, "it was enough to get a 120/130 hp engine, which for personal use and taking into account that weighs 140 kg more than the bike is sufiente. You can get more power but would be usable only with an advanced electronic system management ". What if someone asks you sell an engine like yours? "In fact, I've had offers to build 4 engines for Germany and 10 for England, but for the moment this is not my intention. I did it for personal satisfaction, and after years working on it, I have succeeded. Now let's set it up. If the bike is shown reliable, why not build more engines ?, but for now it is not my intention. Seeing that has attracted attention has been really amazing, a bike created for me my project. I can say I'm on top of happiness. "

[wobbly]

Re LSR attempts on the salt.
I built the pipes for Kiwi - Cory Bertelson's records on a Honda RS250 at Bonneville and as far as tuning is concerned with a
two stroke there are two important factors.
You must run a flat line advance thru the area used from peak Hp into the overev region.
This is to prevent the natural cycle of more retard = more heat = more power = more rpm = richer jetting needed when sitting at your peak speed due to aero and friction.
Once the motor/pipe temp stabilizes, the pipe heat remains constant, as does the fueling then needed for that power level.

Second thing, is to get on the pace as fast as possible,as the weather changes during the day, you should already have a RAD jetting chart done with a load control dyno
so you can do constant rpm at peak power - long enough for the power and egt to stabilize.
If you jet for peak power on a specific day,this will translate into a specific egt number, at a specific RAD.
Do this twice with very different weather combinations, and you can then draw up a chart with a straight line relationship between RAD and jet size.

Here is one for a KZ10 kart engine ( that also has by the way, a straight line ignition ) that was generated using 3 different days, but hitting the same egt on
each day of 640*C ,that was also the peak power egt, before deto, on a constant accelerating inertia dyno - exactly the conditions the kart engine runs under.
This has been used for probably a dozen completely differing RAD days, and I usually change jets every heat race to stay exactly on 640*C, no guessing at all involved.
It has won every race meeting except one second place last year, when we fucked the good motor by leaving all its water on the track.

[oldjohnno]

Thank you Wob, I can't tell you how much I appreciate help like this. Re the target EGT, I'm guessing that if the max hp EGT is only slightly under the det limit then you'd choose that EGT less some safety margin? And where there is some gap between the max power EGT and the onset of det then the actual max power EGT would be the target? My dyno can hold a constant load, so I should be able to maintain it at peak long enough to allow temperatures to fully stabilise as well as verify that the piston will (probably) survive the duration of a run.

[oldjohnno]

What's the general consensus - no, scratch that - what's the smart thing to do with hp measurements to get consistent, meaningful numbers over a range of weather conditions? SAE J1349 JUN90 or some other correction routine? Rules of thumb? Recommended weather instrumentation?

[wobbly]

I contacted Ed Erlenbach about the Banshee ports and here is the map for a stock cylinder.
The numbers are to TDC and with stock pistons there is usually 0.25mm of deck height.
So the TSR number for the Ex port was correct at 30.12 = 89.7atdc = 180.58 duration with 2mm piston offset.

Re dyno correction - I have always used SAE J1349 ( 298K ) and have calibrated my laptop weather station ( called WeatherWatch from
Ozzy company DTec ) that I use at the track, to read the same as the dynos built in unit ( SportsDevices ).
The DTec reads out Temp,RH, Baro,Dyno correction and RAD thru usb connection.
But for an aircooled engine you will need a hand held weather station that has a wind speed detector on it, this way you can arrange the correct air
speed from the dyno cooling fans to get the pipes operating in the same air conditions they see on the salt.
Many are available but make sure it has a direct read out in RAD or Density Altitude and use one or the other all the time, from the same gauge all the time.

[Lef16]

Thank you wob,
my knock gauge is working fine.
Now it's time to set up ignitech and fire up the bike.
Could you give me some guidence for ignitech's advance map?
Cheers

[ief]

I contact Ed Erlenbach about the Banshee ports and here is the map for a stock cylinder.
The numbers are to TDC and with stock pistons there is usually 0.25mm of deck height.
So the TSR number for the Ex port was correct at 30.12 = 89.7atdc = 180.58 duration with 2mm piston offset.


Funny that this is just the one not posted on his site and all else are (looked there as well) but now all is known for sure, tnx Ed (great site with lots of info)

[nitro2tfx]

I contacted Ed Erlenbach about the Banshee ports and here is the map for a stock cylinder.
The numbers are to TDC and with stock pistons there is usually 0.25mm of deck height.
So the TSR number for the Ex port was correct at 30.12 = 89.7atdc = 180.58 duration with 2mm piston offset.





If you like I could play with a rz pack file i have and turn it into the banshee and see if I can get a curve out of it resembling the curve published for the Tr6 exhaust...


Thanks, guys, I think I have enough info now to get going on it.

[peewee]

I contacted Ed Erlenbach about the Banshee ports and here is the map for a stock cylinder.
The numbers are to TDC and with stock pistons there is usually 0.25mm of deck height.
So the TSR number for the Ex port was correct at 30.12 = 89.7atdc = 180.58 duration with 2mm piston offset.

Re dyno correction - I have always used SAE J1349 ( 298K ) and have calibrated my laptop weather station ( called WeatherWatch from
Ozzy company DTec ) that I use at the track, to read the same as the dynos built in unit ( SportsDevices ).
The DTec reads out Temp,RH, Baro,Dyno correction and RAD thru usb connection.
But for an aircooled engine you will need a hand held weather station that has a wind speed detector on it, this way you can arrange the correct air
speed from the dyno cooling fans to get the pipes operating in the same air conditions they see on the salt.
Many are available but make sure it has a direct read out in RAD or Density Altitude and use one or the other all the time, from the same gauge all the time.

some time back I bought a few junk yami twin cylinders for the only purpose of practice welding. luckily you found that map so I don't have to dig these stone age buggers out from under the bench :laugh:. I never did figure why the B floor was lower than A. my brain was hurting the more I tried to understand why so I gave up

[2T Institute]

The current edition of Old Bike Australasia magazine has a great story on the late Bert Flood. It mentions Berts speed attempts on his 350 Bul drag bike in '76, when he ran 152 on a closed-off section of the Northern Highway. Apparently he seized on the first run and had to do a hasty roadside rebuild before backing it up. Some good photos too, I'll put a couple up later.

I wouldn't even try to run petrol on the lake; it'd almost certainly end in tears.

Forget Bert(s) and concentrate on what your going to do. As Mark said the opportunity just to test is very limited. Your testing will be when your there. Water cooled on petrol might be a better option than methanol.

This is what it will be my mates record 133mph production 250 run

https://www.youtube.com/watch?v=LAF6c0c8lk4&feature=youtu.be

[arc100]

deleted post.

[ief]

Thanks, guys, I think I have enough info now to get going on it.

Only thing I doubt is the pin offset Wob mentions and the deckhight (latter will be different engine to engine anyways) The RZ has no pin offset, that all I know.

I'm pretty sure I have an oem banshee piston laying around somewhere so will measure that to make sure. If I find it that is.

[41juergen]

Only thing I doubt is the pin offset Wob mentions and the deckhight (latter will be different engine to engine anyways) The RZ has no pin offset, that all I know.

I'm pretty sure I have an oem banshee piston laying around somewhere so will measure that to make sure. If I find it that is.

At least my Woessner pistons for my RZ have an offset, here only 0.6mm...

[wobbly]

The 2mm pin offset came from Tom Turner and was measured on stock pistons for Banshee - not RZ.
The timing difference is minimal anyway.
The deck height came from a guy who has built many Banshee engines, so I have no reason to doubt his measuring.
But as it stands the port heights are given from TDC, so the deck position is irrelevant.

Its been my experience that if done well, an aircooled on Methanol is quite capable of better performance, with no power fade,over a
watercooled on petrol.
Only caveat would be running 110+ octane race fuel, then the advantage tips in favour of the watercooled.

Re Ignitech advance curve for Lef16 - sure I can give you exactly what the curve should be if I spent 1 1/2 days constructing an Engmod sim file
with every tiny detail of the engines spec.

[peewee]

why would Husqvarna aka ktm use a counter balancer when there was hardly any vibes to begin with, atleast in the 2wheeler frames ? I thought they were pretty smooth compared to the other bikes I have. even with the 300 barell I didn't notice any significant increase in vibration

[Peter1962]

why would Husqvarna aka ktm use a counter balancer when there was hardly any vibes to begin with, atleast in the 2wheeler frames ? I thought they were pretty smooth compared to the other bikes I have. even with the 300 barell I didn't notice any significant increase in vibration

Not so important on an MX bike, but for enduro and even more for trail riding in the woods this will enhance the comfort of the driver. And I think this engine will now also enter the karting market.

[41juergen]

As I need new bearings for my rear wheel I think about using ceramic ball bearings. Of course the much higher costs will not really justify the gain in less friction, but as a "nice to have" :rolleyes:.... Has anybody experience with this type of bearings, are they durable for more than a season? Can I use them also in a street bike?

[cotswold]

As I need new bearings for my rear wheel I think about using ceramic ball bearings. Of course the much higher costs will not really justify the gain in less friction, but as a "nice to have" :rolleyes:.... Has anybody experience with this type of bearings, are they durable for more than a season? Can I use them also in a street bike?

Ask speedpro what he thinks of ceramic bearings

[41juergen]

Ask speedpro what he thinks of ceramic bearings

Jeep, I remember his picture. But wasn't that in the engine?

[wobbly]

I have used ceramic mains in a race engine for 4 seasons and had no issues at all.
The dyno said a gain of 0.6 Hp in 47.8 Hp, but that was over roller mains as used by the factory teams ( that we found were unacceptably unreliable so ditched them
after wreaking two engines ).
But wheel bearings I am not sure about - in that you will have to have lip seals on them anyway,and that produces way more rotating friction than the bearing itself.
Having said that I know of several riders that are adamant the bike will "freewheel " into the pits way faster.
The MicroBlue bearings with polished races and steel balls are very good,and alot cheaper than the ceramic units from the same company - and i use them in classes where
ceramics are not sanctioned.

[Bert]

I have used ceramic mains in a race engine for 4 seasons and had no issues at all.
The dyno said a gain of 0.6 Hp in 47.8 Hp, but that was over roller mains as used by the factory teams ( that we found were unacceptably unreliable so ditched theM..........
:killingme:killingme:killingme:killingme:killingme :psst:
Still to this day suffer sore neck from the high side.
http://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=265496&d=1340517996

[wobbly]

That looks like a ceramic outer race as well as balls that has failed ?
What brand sells those, never seen them before.
The main advantage of ceramic balls is the reduction in inertia = less skidding on the race/cage,I dont see any reasoning in a ceramic race ?
I have used MicroBlue sourced ceramic ball setups ( balls only are ceramic in polished and treated races, with plastic cages ) in literally dozens
of engines and never had a failure.
I would normally change mains every year in an engine that regularly gets raced, but as I say the TM125MX engine that won
3 straight titles = 36 + practice/heats/finals per year - ran for 4 years solid including literally hundreds of dyno runs, and the mains still looked like new, on Elf 909 at 20:1.

[Bert]

That looks like a ceramic outer race as well as balls that has failed ?
What brand sells those, never seen them before.
The main advantage of ceramic balls is the reduction in inertia = less skidding on the race/cage,I dont see any reasoning in a ceramic race ?
I have used MicroBlue sourced ceramic ball setups ( balls only are ceramic in polished and treated races, with plastic cages ) in literally dozens
of engines and never had a failure.
I would normally change mains every year in an engine that regularly gets raced, but as I say the TM125MX engine that won
3 straight titles = 36 + practice/heats/finals per year - ran for 4 years solid including literally hundreds of dyno runs, and the mains still looked like new, on Elf 909 at 20:1.

Out of high speed milling machine. Not doubting ceramics are the go. I can believe your figures from what I experienced in terms of free rolling.
Key is to make sure no side / lateral loading. I slightly fked up the machining of the primary drive spacer, loading onto the core of the bearing. Race collapsed then chomp chomp... Sudden stop and over the handle bars... :pinch:

[Flettner]

why would Husqvarna aka ktm use a counter balancer when there was hardly any vibes to begin with, atleast in the 2wheeler frames ? I thought they were pretty smooth compared to the other bikes I have. even with the 300 barell I didn't notice any significant increase in vibration

Perhaps not just vibration? With the 450 4T's they use a counter rotating ballance shaft with fairly heavy counterweights, these bikes turn way better than they should. I think some of the crankshaft gyroscopic effect is offset by the counter shaft. Could be wrong, but I think as the crank gets bigger the effect is felt more by the rider (ride a TT500 and see what I'm saying). That's why I've started to build (but stopped due to cost to finish) the 360 reverse rotation crank engine, also happens to be variable RV and EFI.
But as I said earlier on another thread the EFI, variable RV F9 is going so well I'm keen to get the 360 up and running now. Perhaps 70HP is not a dream after all:blink:
I'm going to compromise the design and just run a throttle cable straight to the RV slide, without the expensive ECU fly by wire control. First up anyway, if it works well then I'll save my pennies.

[TZ350]

321586

Well I got to try the small low speed injector in its new location. Totally changed things, it ran absolutely rat shit. Had to double the map numbers to get it to run at all at the low end. The injection-end timing had to be totally different too. A bit of re mapping work to do now, hopefully it being so different is a good thing.

[Frits Overmars]

Well I got to try the small low speed injector in its new location. Totally changed things, it ran absolutely rat shit. Had to double the map numbers to get it to run at all at the low end. The injection-end timing had to be totally different too. A bit of re mapping work to do, hopefully it being so different is a good thing............321590

[FastFred]

........... 321590

................. So True

[arc100]

Can anyone help me out?

I'm looking for a port angle and dimensions map for a HH TZ250 84 cylinder.

Thanks.

[F5 Dave]

I've got one right here, . . . no wait, its a box of cereal. Sorry about that.

[husaberg]

Wob will probably remember a conversation years ago about Roberts carbs.
I found these pics today.
(later)
later, traditional Keihins
321622
Vs what I suspect are the original engines Roberts carbs.
321623

[wobbly]

Now that is really interesting.
I have never seen the early Roberts engine ( upside down compared to what was raced, and the BSL tripple with 2 up ) but they found as I did that the Keihins ( read zillion dollar )
when run back to front,would pull the floats down on the fulcrums and flood under brakes.
So they went back to the original carbs that were pump around with a weir system in the bowl.

[TZ350]

.

Tonight we were making great progress with the 50, the Team were pulling great runs, changing jets and tweaking the ignition.

Just when we had done all the runs and finished up with the best power and curve then someone noticed it had all been done with the choke on, :doh: flipping it off and it all turned to mush .....Bugger ... LOL ... another day tomorrow I guess.

[chrisc]

Hahaha claaassssiiiccc! Did you change the ignition on the 50 Rob? Was that the problem?

[2T Institute]

:killingme:killingme:killingme:killingme:killingme :psst:
Still to this day suffer sore neck from the high side.
http://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=265496&d=1340517996
The white ceramic balls are Zirconiated and cannot handle loads or shock, proper ceramic bearings have black balls by Cerbec made from Silicon nitride. That has never happend with Cerbec/St Gobain balls. I have heard stories of them being hit with a hammer on a steel plate and only mark a little. Have used them for ages and back for buck wheel bearings make a massive difference. A bike fitted with ceramic wheel bearing is easier to push around in gear with the clutch in than a bike without in neutral.

[Frits Overmars]

Just when we had done all the runs and finished up with the best power and curve then someone noticed it had all been done with the choke on, flipping it off and it all turned to mush .....I know the experience; we once had it on the track. After a record practice lap somebody noticed the choke was still on.
Exuberance! Rectifying this would certainly bring another second or two!
You guessed it: with the choke off the rider never managed to equal his record lap. He said the power came in much more friendly when the choke was on.


A bike fitted with ceramic wheel bearing is easier to push around in gear with the clutch in than a bike without in neutral.I like to think I have an open mind, but not that open....

[TZ350]

I know the experience; we once had it on the track. After a record practice lap somebody noticed the choke was still on.
Exuberance! Rectifying this would certainly bring another second or two! You guessed it: with the choke off the rider never managed to equal his record lap. He said the power came in much more friendly when the choke was on.


We were tempted to just leave the choke on, and use it like that .... :rolleyes: .... still it showed up some interesting things about the fueling.


Hahaha claaassssiiiccc! Did you change the ignition on the 50 Rob? Was that the problem?

Pretty obvious it was electrical and to find the fault we did it scientifically, changed one part at a time, first the CDI, then the Stator next was going to be the coil, turned out to be the new spark plug...... :crazy: ..... :facepalm:

[wobbly]

Frits, you need to purchase some mind opening substances readily available near you.
I have been told by several race teams that bikes fitted with ceramic wheel bearings will coast twice as far after a plug chop.
Now I am as skeptical as all hell, but they seem more than happy to pay silly money for the damn things,so I should just cough up and do a dyno run down test.
I suppose the metal shield type bearings wont have near the rolling friction of rubber lip types, but that provides very little protection from ingress of shit
and water - so I dont know what to do about that as the bearings are so expensive you simply dont want to ruin them by not sealing them properly.
Whats the go Lozza?

[Bert]

The white ceramic balls are Zirconiated and cannot handle loads or shock, proper ceramic bearings have black balls by Cerbec made from Silicon nitride. That has never happend with Cerbec/St Gobain balls. I have heard stories of them being hit with a hammer on a steel plate and only mark a little. Have used them for ages and back for buck wheel bearings make a massive difference. A bike fitted with ceramic wheel bearing is easier to push around in gear with the clutch in than a bike without in neutral.

Zirconiated ceramic, yip, I did have a bit of fun trying the replicate the collapse (on the other bearing) with a sledge hammer. But unsuccessfully. So it's mounted on the wall next to the large number of Pistons...

Silicon nitride seems likely for the next attempt - once we fix the cylinder issue.

[2T Institute]

I like to think I have an open mind, but not that open....

Well the bikes are here whenever your ready to try Frits :msn-wink: Wob have run the microblues in all types of conditions including very harsh conditons(make of that what you will) with seals. Use 4 drops of oil a year. Ran then in karts with a great results and yes they will coast for a long time top speeds are not increased notably but the time taken to get there is less. I had a long conversation with a coach of the NSW Institute of Sport junior cycling team about ceramics and what they do for a humble push bike (concealed motors apparently work best :laugh:) was metres on a velodrome and higher average kmph on the road(wheels and crankset)

[peewee]

if you leave off the wheel hub seals it reduces the rolling friction quit a bit. then just use any type of bearing with rubber seals covering the balls. dirt or water shouldn't be much of a problem unless your off road. ive already experimentd with this. without hub seals causing friction on the axle spacer it rolls much easier

[Grumph]

if you leave off the wheel hub seals it reduces the rolling friction quit a bit. then just use any type of bearing with rubber seals covering the balls. dirt or water shouldn't be much of a problem unless your off road. ive already experimentd with this. without hub seals causing friction on the axle spacer it rolls much easier

Leaving the seals off and using oil as a lube for wheel bearings is an old trick. It goes back to short circuit racing where essential maintenance between meetings was wheels out and wash bearings. Easier to do in the days where only one tyre type meant only one set of wheels...

[oldjohnno]

I'm curious about transfer flow, specifically at times when the transfer is partially open (piston above BDC) and would love to hear any comments.

Obviously, at any point other than BDC the piston forms part of the short side radius of the transfer. There'll be a ledge on the bottom of the port window and then from there a sharp internal right angle up the side of the piston and then up to another sharp turn across the top of the piston crown. Only at BDC will the short side of the port be nicely shaped and at other points there must be a massive amount of turbulence around this turn.

There's not a lot you can do about it I guess - short of putting a huge radius on the edge of the piston crown so that it forms the short turn of the transfer. But this I guess would affect combustion terrribly and you'd have to run the top ring quite low on the piston.

Does it even matter? Does most of the flow occur at or around BDC any way? Does managing the flow in a partially open transfer warrant any attention?

[wobbly]

Adding a small radius to the piston and reshaping the squish to suit gave about 1 Hp in high 40s when dynoed by VHM.
But that was with a billet machined piston, so the power change could be just as much be caused by that.
There is more pressure above the transfers when they open than is in the duct, so reverse flow occurs - this is how port stagger works to affect the scavenging regime.
And the pressure differential created at the exhaust port around BDC by a correctly dimensioned diffuser,is way way more than that created by compressing the case due to piston movement.
Thus the flow regime as the piston approaches, then dwells at BDC, then starts to move upward is the critical period for the inner radius and the approach angle
of the port floor to be optimized.

[TZ350]

I'm curious about transfer flow, specifically at times when the transfer is partially open (piston above BDC) and would love to hear any comments.

It has been talked about on here before, from memory a small radius (with matching squish profile) on the edge of the piston is beneficial, And the trick with pipes is to get them to suck hard at BDC. Hopefully someone will be able to find the original posts.

Wob beat me to it, anyway the top of page 1500 has a very helpful post about ways to search this thread.

[bjorn.clauw.1]

It has been talked about on here before, from memory a small radius (with matching squish profile) on the edge of the piston is beneficial, And the trick with pipes is to get them to suck hard at BDC. Hopefully someone will be able to find the original posts.

Wob beat me to it, anyway the top of page 1500 has a very helpful post about ways to search this thread.

Page 1271

Searching the forum with google custom search, it even shows pictures

https://cse.google.com/cse/publicurl?cx=009468122799118164990:5pd9xdluxce

[Frits Overmars]

I'm curious about transfer flow, specifically at times when the transfer is partially open ... Obviously, at any point other than BDC the piston forms part of the short side radius of the transfer. There'll be a ledge on the bottom of the port window and then from there a sharp internal right angle up the side of the piston and then up to another sharp turn across the top of the piston crown. Only at BDC will the short side of the port be nicely shaped and at other points there must be a massive amount of turbulence around this turn.
There's not a lot you can do about it I guess - short of putting a huge radius on the edge of the piston crown so that it forms the short turn of the transfer. But this I guess would affect combustion terrribly and you'd have to run the top ring quite low on the piston.
Does it even matter? Does most of the flow occur at or around BDC any way? Does managing the flow in a partially open transfer warrant any attention?A radius on the piston edge greatly improves inflow from the transfers into the cylinder and it hardly improves any unwanted flow from the cylinder into the transfers.
And this radius doesn't need to be huge. I use 5% of the stroke as a radius. Of course the combustion chamber shape must be adapted to this radius.
It not only helps flow from the transfers into the cylinder; it also helps flowing washed-through mixture from the exhaust duct back into the cylinder.
Remember, when in the right rpm range, at transfer closure the exhaust port should stop being an exhaust port and should turn into a transfer port.
A radiused piston edge also helps to conserve energy during the supercritical first part of the blowdown phase because it lessens turbulence; especially in combination with a radiused top edge on the exhaust window.
321758

[Frits Overmars]

Adding a small radius to the piston and reshaping the squish to suit gave about 1 Hp in high 40s when dynoed by VHM.... the flow regime as the piston approaches, then dwells at BDC, then starts to move upward is the critical period for the inner radius and the approach angle of the port floor to be optimized.My approach: in BDC the extended transfer floor direction touches the piston tangentially.
321759

[bjorn.clauw.1]

My approach: in BDC the extended transfer floor direction touches the piston tangentially.
321759

Hi Frits, so when we take the piston out to turn this radius, would it be wise to make a small radius on the bottom of the piston skirts? Found in a book this helps to keep more oil on the bore wall (in that the sharp edge of the skirt acts as an oil scraper).

[richban]

I have been playing around with the exhaust port on the 300 cylinders. I have added some side angle to the port. Not much as the casting is very thin there and could easy pop out into the water jacket. But some has got to be better than the none it has.

Now there is quite a bit of space between the port and the power valve sides. Especially when fully closed. Also you will see the space in the centre beside the bridge is quite large. I am thinking I should weld up and reshape the PV. Is this worth the effort? My gut says yes. Any advice appreciated. Cheers Rich.

321776

[wobbly]

Honda A kit setups have exactly the same approach Rich, but the slanteye festerers weld the PV with tig, and make it fit the bridge
and the side cutaway perfectly, in the up and down position - easy to do, but takes time to grind at to get it to fit.
Also when the valve is up, the whole thing should seal around the cavity, again a run of tig around the blades bottom face is easy to fill and grind..
I did the welding on a CR125 PV to make it fit the bridge exactly and picked up 1.5 Hp at 9000.

[richban]

Honda A kit setups have exactly the same approach Rich, but the slanteye festerers weld the PV with tig, and make it fit the bridge
and the side cutaway perfectly, in the up and down position - easy to do, but takes time to grind at to get it to fit.
Also when the valve is up, the whole thing should seal around the cavity, again a run of tig around the blades bottom face is easy to fill and grind..
I did the welding on a CR125 PV to make it fit the bridge exactly and picked up 1.5 Hp at 9000.

Cheers for that, As I figured after seeing an RS250 barrel, the valve fits very well indeed. Time to get the tig out. Also I have checked glens cut up barrel and it looks like I can take another 1mm or so out to get a little bit more angle depth and curve out of the sides.

[bjorn.clauw.1]

Had some time this morning to finish my cast iron "wet" liner. (credits/thanks to Makr and everybody on this forum actually). This will go on the mule engine when the dyno is finished.

321792321793321794321795

I acid etched the ports in the liner and transfered the port geometry to the inside of the liner. I then milled the ports on a conventional lathe. Very time consuming. I wonder if anybody made a jig (much like a wood copy carver) to copy the ports from another cylinder onto the sleeve?

[seattle smitty]

Yes Sir!!! THAT is one way you can get improved heat transfer out of an iron sleeve!!

Have you got a way to promote a forced directional flow of the coolant through and around the slots in the sleeve? Like maybe with the coolest incoming water flowing over the exhaust side first??

Incidently, since I can't tell for sure from the photos, does the sleeve positively seat into the barrel at some point, or are you just retaining the sleeve with the interference fit? Does it seat at the bottom of the water jacket? IF so, is it just metal on metal with some kind of goop-sealant, or was there room for an O-ring?

[bjorn.clauw.1]

I forgot to take pictures with the sleeve out. Here's an artistic rendering of the fitment.
321796

o-ring is the same one that seals the combustion chamber.

interference fit is 0.12mm. A lot, the idea behind this is that it will help the heat transfer. Also the bore size of the sleeve shrunk from 54.04mm to 54.01mm. so I hope it will expand a little bit faster than cast iron in general because it is under compression from the aluminum cylinder. So when the cylinder expands the sleeve will follow. (tests with a hotplate seem hopeful).

Cooling fluid comes up from under the exhaust port, then around the outer cylinder wall. This is blocked now (not in the pictures) so it is forced through the cast iron slots (left 2 small bleed holes, one on either side). Then the coolant exits the sleeve above the intake port where it goes over the cylinder head and flows back (over the cylinder head) to the exhaust side where it exits the cylinder head cover.

Sleeve is pulled/fixed onto its shoulder by the cylinder head. No provision to keep the sleeve from rotating. To install the sleeve I turned down an aluminum tube that has a slipfit with the sleeve bore. I then welded both sides and installed a water in and out connection. So during the fitment the sleeve is cooled from the inside with running tapwater through the aluminum pipe. (did not block until I turned the water off)

[lodgernz]

Please forgive me if this post is too far off-topic for this thread.

I may be misreading things, but it seems to me that the 125GP class in NZ is dying a slow death due to the increasing cost and difficulty of maintaining the engine of the only competitive unit, the RS125, long since abandoned by Honda in any useful context.
There appear to be no foul-strokes that can make the grade, even given their huge capacity advantage under the current MNZ rules, and no competitive 2-stroke alternatives are jumping out of the woodwork.
As far as I know, the only 125 2T left in current manufacture is the KTM SX125. I'm wondering, would it be possible to coax the 45 or so HP required to make this engine a viable substitute for the RS125 if developed sufficiently and shoe-horned into the RS frame?
If a 2T substitute is not found soon, I can see corrupt FIM legislation will eventually trickle down to NZ and we'll be stuck with a poxy 4T class, inevitably of 250cc and dominated by Honda.
Are there any competitive kart engines that could be modified to fit the RS frame?

Opinions?

[wobbly]

There used to be a class in karting here called 125 National.
We won 3 titles in a row and still have the lap records at every track we raced using a TM125MX engine.
This was ( is ) way cheap to maintain, REAL easy to tune,and if you wanted to get smart all the ratios from the other TM kart engines will fit.
That engine ended up with 50.2 Hp,at the sprocket on Avgas ( 10 years ago,I would get way more now ) and as the PV was converted to be driven by a cable servo, it had WAY
more power down at 10,000 than any RS125 ( our main competition ).
The problem with the dedicated kart engines is that the carb is out the front, but having the pipe under the seat is an advantage power wise.
Its common knowledge that the Aprilia RSA125 didnt handle as well as the RSW125 due to the engine having to be moved back away from the front tyre to increase carb clearance.
But take a TMKZ10 kart engine and replace the 30mm carb with an SPJ38 and fit an Ignitech and that is well over 50 Hp at the sprocket without touching a thing.
Bore one to 60mm,giving 152cc and its over 60.
But as a side point we get 41.5 Hp at the sprocket from a 2002 CR125 dead stock except for the reeds and the pipe for SKUSA racing, throw on a 2004 cylinder with cable PV,do some porting
and your RS125 will get blown away easy.
A complete SKUSA engine parts kit is still available from HRC for under 2000 USD,and I bought a siezed 2004 cylinder,to fit on an old NSR250 MC21, here in NZ
the other day for $200, they are available new on line for around 400USD complete.
The CR125 may be wet clutch, but fit Hinson alloy/kevlar plates and you would never know, and they last forever.
Cheap as chips the whole thing.

[FastFred]

321586 Well I got to try the small low speed injector in its new location. Totally changed things, it ran absolutely rat shit. Had to double the map numbers to get it to run at all at the low end. The injection-end timing had to be totally different too. A bit of re mapping work to do now, hopefully it being so different is a good thing.

321797

Gave TeeZee a hand over the weekend with testing the new injector position, well its no magic bullet. But we did learn a lot about how critical timing the injection event is. Having high and low injectors in two completely different places with one timed to the transfer ports and the other needing to be timed to the inlet looks like an insurmountable problem, for now anyway. It still runs Rat-Shit.

Back to the drawing board. ... :rockon:

[chrisc]

Please forgive me if this post is too far off-topic for this thread.

I may be misreading things, but it seems to me that the 125GP class in NZ is dying a slow death due to the increasing cost and difficulty of maintaining the engine of the only competitive unit, the RS125, long since abandoned by Honda in any useful context.
There appear to be no foul-strokes that can make the grade, even given their huge capacity advantage under the current MNZ rules, and no competitive 2-stroke alternatives are jumping out of the woodwork.
As far as I know, the only 125 2T left in current manufacture is the KTM SX125. I'm wondering, would it be possible to coax the 45 or so HP required to make this engine a viable substitute for the RS125 if developed sufficiently and shoe-horned into the RS frame?
If a 2T substitute is not found soon, I can see corrupt FIM legislation will eventually trickle down to NZ and we'll be stuck with a poxy 4T class, inevitably of 250cc and dominated by Honda.
Are there any competitive kart engines that could be modified to fit the RS frame?

Opinions?

Misreading? I'm wondering where you're doing your reading at all lodger? I don't blame you though, most racers in NZ shoot down 125GP without trying to understand the class.
When I started racing 125GP in NZ a year ago, everyone tried to talk me out of it here in Auckland saying that it was a dying class. I pressed on anyway because I knew it's what I wanted to do, knew how much it could teach me compared to racing a production 250 or 650 diesel. It has been the best decision I've ever made for my racing and I've come so far in 1 year I can barely believe it. What an incredible experience! Even doing both the spannering and racing. Thank you so much to this forum and to the incredible people around the country who are so willing to give guidance.

What I found when I started was a class with very little to no communication, virtually no media or technical support in a class that sorely needs it, running on word of mouth and hearsay. No WONDER the class gets such crap thrown at it. Every barrier to entry of this amazing class was 10 metres high, with no clear avenues for new riders to join the class or ways to support it. Between myself and my friend Chris Malcolm (also Auckland 125 rider), we've really started to turn it all around, hell it's growing!!! In the last year, Auckland has gone from 1 part time 125 rider to SIX full time 125 riders. That's massive considering 125s have always been driven strongest from the south (hence up until recently, the string of south island national champs). Steve Ward in the south island does an incredible job of flying the 125 flag super high and has also had a spike in interest down there. He's flat out. There is renewed national interest in the class and we've been able to get bikes dragged out from sheds. We now get frequent messages of interest to join the class and we're even looking at getting bikes the USA to people have bikes to ride. At a Taupo practice day recently we had 4 125s, at a Hampton Downs practice day this weekend we'll have 4 or 5 125s, 2 weekends ago at Levels I was there and we had 5 125s (would have been 6 if not for an injury). 2017 nationals I'm expecting a marginal growth due to new riders getting comfortable with bikes but the following year, we're expecting a proper 125 presence.

Engines. As Wob pointed out, the stock NX4 RS125 is hardly an impressive engine by todays standards and we could do far better if we wanted to chase power. Do we need to change this? I don't think so. They're for sure fast enough to embarrass much larger bikes with the right rider. Also they're pretty straight forward and reliable engines. Bikes in the class currently are mainly stock which I see as a very good thing! Closer racing and more time understanding the in's and out's of the bikes rather than throwing $ at aftermarket parts and starting an arms race. Even worse, a missed opportunity for the rider and mechanics to learn the core fundamentals this class brings: preparation, precision and consistency. The worst thing for this class would be to further over complicate an already relatively (to 4t production bikes) tech heavy class. Yes the engines are no longer manufactured which does mean eventually, when all the worlds supply is wasted, the class might stand a chance of "dying". I'm willing to wager however that much like classics out there, reproduction parts will be created to meet demand. I do believe we have many years left in this class and I urge those to take advantage of it if you get even half a chance.

Cost. I honestly, truly believe that running a 125GP bike is not very expensive. I'm 26, no sponsors, no mechanic, all self funded obsession. Racing the nationals in ANY class is expensive, running the 125GP bike itself is very affordable. A 125GP bike is not a production 250 4 stroke and what you learn on a 125GP bike is far greater than what you learn on a 250 4 stroke. So yes, a 125GP bike is more expensive to run than those water pumps. A 125GP bike is also not a 600 super sport. You want expensive, try the tyre bill on a 600! Tyres on a 125 last forever and you can sell them back to bucket racers and regain most of the initial outlay. Fuel, oil, parts are all available and affordable if you use your head. The pistons we run through the nationals only end up doing 1/3 of their useful life so we use them again for club racing the full rest of the year. Do you even need to run a new top end every round to be competitive at the nationals? Nope. If you're a good rider do you even need brand new tyres every round of the nationals to be competitive? Nope. Seriously. Can you do that on a bigger 4 stroke? Nope. What we have is this brilliant class for mechanics and riders to learn fundamentals of racing with a reasonable cost. If only more people understood that. Where will that happen if this class disappears? Definitely won't happen in the introductory 250 classes and most don't have the wallet to compete in 600s.

As you can tell I have a massive amount of enthusiasm for this class which has given me so much in such a short period of time. We're putting a great deal of energy into making sure new riders find bikes and are all set up ready to race. So far the reception has been incredibly positive and I hope we can change the conversion to align with what is actually happening where it counts, on the race track. Want to know more about 125s? Either contact me directly or ask on the 125 facebook page: www.facebook.com/groups/125GPNZ (https://www.facebook.com/groups/125GPNZ)

https://c2.staticflickr.com/8/7157/27180022135_f3d80c3da0_b.jpg

Note, photo from last round of NZSBK 2016 and doesn't include a large portion of the fleet of new riders coming through now. We also had 2 injuries in the south island meaning they didn't come up for this round.

[crbbt]

Wob: I had thoughts of using a CR cylinder on the RS as it would be a cheap powervalve cylinder a few years ago. I was promptly told that this was a silly idea :facepalm:

given that the CR's generator isn't 12v. do you have to run total loss ignition?





I can only echo chrisc points. similar position (27, no sponsorship, own mechanic) deterred away from the 125's because "they're expensive" by everyone with a passing interest in bike racing. ASBK have just split the 125's into a separate class over here. the running costs of a production Moto 3 honda is about 3 times that of the 125. only thing I find a struggle is getting good advice cheaply. must be how Italian do business :laugh:

[wobbly]

All the CR ignitions from about 2002 onward are 12v to drive DC ignitions and powerjets ,TPS and powervalves ( 04 ) so these will bolt
straight onto earlier models.
The later RS125 kit engines with PV and the short ( 800mm ) pipe with 200* Ex are easily replicated using the 04 CR cylinder as it had a cable
PV as standard - the only model that did.
It has reverse transfer stagger like an Aprilia, a really nice small oval Exhaust duct exit, and could easily be ported to make well over 50 Hp.
And with the PV in place it would jet past any bog RS125 out of every turn, due to the gearing enabled by the great overev.
Here is a dyno sheet ( rear wheel Hp ) of a well tuned customer Honda, a B kit, and Azuma's A kit with PV - I know what I would be trying to replicate.

[chrisc]

Isn't that is a carrot in front of a crowd of stink wheel fiends if I've ever seen one. Thanks for posting that Wob!

[lodgernz]

Brilliant reply Chris, and don't get me wrong, I love the 125GP class. Nearly won it myself once upon a time. It's the only pure racing class left in NZ outside of buckets and sidecars.
I've just been concerned to see the numbers dwindling, and to hear that parts are getting harder to find, with no obvious successor to the RS.
Your enthusiasm is obviously already rubbing off on new riders, and that is exactly what is needed. The stronger the class becomes numerically, the easier it will be to find sponsorship.
I wish you and the class well.

Thanks also Wobbly for your comments. Clearly faster 125s can be built without horrendous expense, but I'm inclined to agree with Chris that the class is more attractive to a newcomer as a pseudo one-make class, for the moment anyway.

[wobbly]

Yep, it would be impossible to compete against an engine that had the same power at 13800 as a well tuned stocker has at 12200.
As i say, the CR cylinder is well capable of being tuned to even above this level, is cheap and available.
Add a long 110 rod from say Samarin with a plate and you have what won the last 250GP championship.
Slap on an Ignitech, a modern fat pipe, a VF2 and you are well into the 50Hp zone cheaply with ease..

[chrisc]

Are you able to comment on the CR125 cranks and how they'd take the abuse in a road racer vs MX bike Wob? The service interval on the NX4 crank is 2,000 kms, how would they compare.

It'd be a fun exercise to build a NX4 into a superlite/F3 class beating 2 stroke with an engine you described Wobbly! :ar15:

[2T Institute]

Please forgive me if this post is too far off-topic for this thread.

I may be misreading things, but it seems to me that the 125GP class in NZ is dying a slow death due to the increasing cost and difficulty of maintaining the engine of the only competitive unit, the RS125, long since abandoned by Honda in any useful context.
There appear to be no foul-strokes that can make the grade, even given their huge capacity advantage under the current MNZ rules, and no competitive 2-stroke alternatives are jumping out of the woodwork.
As far as I know, the only 125 2T left in current manufacture is the KTM SX125. I'm wondering, would it be possible to coax the 45 or so HP required to make this engine a viable substitute for the RS125 if developed sufficiently and shoe-horned into the RS frame?
If a 2T substitute is not found soon, I can see corrupt FIM legislation will eventually trickle down to NZ and we'll be stuck with a poxy 4T class, inevitably of 250cc and dominated by Honda.
Are there any competitive kart engines that could be modified to fit the RS frame?

Opinions?

Is the famous Kiwi ingenuity is dead then? In superkarts here in Australia a friend of mine pioneered several things that are now de rigueur in superkarts. All on a humble old NF4 engine that ended up nudging 45hp. All done with off the shelf parts, no expensive " A/B/C/D kit" parts most of them we got off ebay. That engine ran rings around karts that someone spent $5000 on a NX4 rebuild. We even tested a $18 conrod from Thailand that worked a charm.
A recent race meeting on a tight track a very good rider with a CR85 engine in a NF4 frame won races outright against a NX4. Point is the humble NF4(like a RSW 125) is still a very capable bike in the right hands.

[wobbly]

The CR125 crank parts are same same as RS125 quality wise and last forever over 12,000 rpm in a SKUSA engine.
I think Lozza has looked at putting a HotRods CR125 crank into the RS as it has higher inertia, and revs on better ?

[seymour14]

Is the famous Kiwi ingenuity is dead then? In superkarts here in Australia a friend of mine pioneered several things that are now de rigueur in superkarts. All on a humble old NF4 engine that ended up nudging 45hp. All done with off the shelf parts, no expensive " A/B/C/D kit" parts most of them we got off ebay. That engine ran rings around karts that someone spent $5000 on a NX4 rebuild. We even tested a $18 conrod from Thailand that worked a charm.
A recent race meeting on a tight track a very good rider with a CR85 engine in a NF4 frame won races outright against a NX4. Point is the humble NF4(like a RSW 125) is still a very capable bike in the right hands.

It's not dead...just looking for other challenges.:shifty:

[Frits Overmars]

Hi Frits, so when we take the piston out to turn this radius, would it be wise to make a small radius on the bottom of the piston skirts? Found in a book this helps to keep more oil on the bore wall (in that the sharp edge of the skirt acts as an oil scraper).Yes, the idea is to make the piston skirt 'water ski' over the oil film instead of scraping the oil off. You don't really need a radius there, a 5° chamfer will do fine.


... the Aprilia RSA125 didnt handle as well as the RSW125 due to the engine having to be moved back away from the front tyre to increase carb header clearance.Corrected that for you Wob.

[lodgernz]

It's not dead...just looking for other challenges.:shifty:

Time for a GPR-framed special 125GP bike?

[Bert]

Time for a GPR-framed special 125GP bike?

Wouldn't that be cool. A class take over :corn:
It's not as stupid as it sounds, right engine and supply of consumables (forks, wheels & swingarms).:niceone:

[mr bucketracer]

Time for a GPR-framed special 125GP bike?just some clean burning 4 strokes would be the way:niceone:

[wobbly]

Yea, sorry Frits,good someone is on his feet - of course, the header is out the front on the RSA.
Be interesting to see how a kart engine layout would work with the carb out the front.
Probably quite well now that the carbs are all pointing downward,and the whole engine could be rotated down at the front even more in a bike.
And as for clean burning 4Ts in racing, yea right,the tdc overlap numbers needed to generate 250 odd Hp in a 1000cc MotoGP engine
means plenty of hydrocarbons are floating around Mugello,as well as the oil smoke from Rossi's shitter.

[seymour14]

just some clean burning 4 strokes would be the way:niceone:

Cleaner emissions then what you would suck out of a wobblybong...;)

[wobbly]

I put single malt into my bong - so yea plenty of emissions there.

[seymour14]

I put single malt into my bong - so yea plenty of emissions there.

Now ya talking, must try one sometime!:niceone:

[chrisc]

just some clean burning 4 strokes would be the way:niceone:

Yuck. Sounds good to me though, lets race. My outdated, slow, stock NX4 chewed up the IM on Hampton's straight despite Dave throwing massive stabs at me every lap :shutup:
Let's not bring moto3's into the discussion now :blink:

[mr bucketracer]

Yuck. Sounds good to me though, lets race. My outdated, slow, stock NX4 chewed up the IM on Hampton's straight despite Dave throwing massive stabs at me every lap :shutup:
Let's not bring moto3's into the discussion now :blink:just want to boost the class , oh well guys do live in the past (-: , back to project x me thinks , have to say my 550 svx aprilia has nealy sent me to the grave , building a 2 stroke seemed way easyer321841

[TZ350]

Page 1530 ......

Searching the ESE thread.


Searching the forum with google custom search, it even shows pictures

https://cse.google.com/cse/publicurl?cx=009468122799118164990:5pd9xdluxce

Knock Gauge


Here is the link to the knock gauge - you can order with a grounding output to trigger an Ignitech retard function and/or
a 0-5V output for a datalogger.
This really is the best thing since sliced bread.
Its cheap,and works perfectly.

http://www.ebay.com/itm/Knock-gauge-for-detonation-sensor-klopfsensor-NEW-with-output-/111623836064
(http://www.ebay.com/itm/Knock-gauge-for-detonation-sensor-klopfsensor-NEW-with-output-/111623836064%5b/QUOTE)



If you adjust the sensitivity so that the pre deto light just flickers occasionally when under hard full load acceleration, then you know for sure
that as soon as a real "knock " event occurs the deto led will light up instantly.



Hey wob, I've got a problem with knock gauge here.
I bought it from ebay and I bought a Bosch knock sensor for Peugeot or Citroen.
Yesterday I wired it up and tested it. When I give 12V to it one or two green lights give a strong flash and after a moment only one green light is on.I tried to hit with a plastic hammer but nothing changer,not even 2nd green light flashed. I tried to change the sensivity but nothing changes.



Installed mine last week. Bosch nr 0 261 231188. Hitting it with something plastic doesn't work. Needs to be metal (gently tapping the bolt with a spanner works for me).


One green led tells you its running, and yes if you tap the mounting bolt with a steel hammer another couple of lights should flash.
A firm crack from the hammer will show the deto led.Actual deto is just like hitting the piston with a steel hammer - this is why the head or cylinder nuts can be loosened when it happens.

You can adjust the sensitivity with the engine running so that under acceleration all the lights flicker except the deto led.

The 0-5V output works real well on a datalogger,as I can read the voltage level to the point of seeing a few 5V spikes with every speedshifted gearchange - so anything approaching real deto at any rpm/throttle position is dead obvious.

RS125


I may be misreading things, but it seems to me that the 125GP class in NZ is dying a slow death due to the increasing cost and difficulty of maintaining the engine of the only competitive unit, the RS125, long since abandoned by Honda in any useful context.

There appear to be no foul-strokes that can make the grade, even given their huge capacity advantage under the current MNZ rules, and no competitive 2-stroke alternatives are jumping out of the woodwork.

As far as I know, the only 125 2T left in current manufacture is the KTM SX125. I'm wondering, would it be possible to coax the 45 or so HP required to make this engine a viable substitute for the RS125 if developed sufficiently and shoe-horned into the RS frame?

If a 2T substitute is not found soon, I can see corrupt FIM legislation will eventually trickle down to NZ and we'll be stuck with a poxy 4T class, inevitably of 250cc and dominated by Honda.
Are there any competitive kart engines that could be modified to fit the RS frame? Opinions?


There used to be a class in karting here called 125 National.
We won 3 titles in a row and still have the lap records at every track we raced using a TM125MX engine.
This was ( is ) way cheap to maintain, REAL easy to tune,and if you wanted to get smart all the ratios from the other TM kart engines will fit.
That engine ended up with 50.2 Hp,at the sprocket on Avgas ( 10 years ago,I would get way more now ) and as the PV was converted to be driven by a cable servo, it had WAY
more power down at 10,000 than any RS125 ( our main competition ).
The problem with the dedicated kart engines is that the carb is out the front, but having the pipe under the seat is an advantage power wise.
Its common knowledge that the Aprilia RSA125 didnt handle as well as the RSW125 due to the engine having to be moved back away from the front tyre to increase carb clearance.
But take a TMKZ10 kart engine and replace the 30mm carb with an SPJ38 and fit an Ignitech and that is well over 50 Hp at the sprocket without touching a thing.
Bore one to 60mm,giving 152cc and its over 60.
But as a side point we get 41.5 Hp at the sprocket from a 2002 CR125 dead stock except for the reeds and the pipe for SKUSA racing, throw on a 2004 cylinder with cable PV,do some porting
and your RS125 will get blown away easy.
A complete SKUSA engine parts kit is still available from HRC for under 2000 USD,and I bought a siezed 2004 cylinder,to fit on an old NSR250 MC21, here in NZ
the other day for $200, they are available new on line for around 400USD complete.
The CR125 may be wet clutch, but fit Hinson alloy/kevlar plates and you would never know, and they last forever.
Cheap as chips the whole thing.


Wob: I had thoughts of using a CR cylinder on the RS as it would be a cheap powervalve cylinder a few years ago. I was promptly told that this was a silly idea :facepalm:

given that the CR's generator isn't 12v. do you have to run total loss ignition?

I can only echo chrisc points. similar position (27, no sponsorship, own mechanic) deterred away from the 125's because "they're expensive" by everyone with a passing interest in bike racing. ASBK have just split the 125's into a separate class over here. the running costs of a production Moto 3 honda is about 3 times that of the 125. only thing I find a struggle is getting good advice cheaply. must be how Italian do business :laugh:


All the CR ignitions from about 2002 onward are 12v to drive DC ignitions and powerjets ,TPS and powervalves ( 04 ) so these will bolt straight onto earlier models.
The later RS125 kit engines with PV and the short ( 800mm ) pipe with 200* Ex are easily replicated using the 04 CR cylinder as it had a cable
PV as standard - the only model that did.
It has reverse transfer stagger like an Aprilia, a really nice small oval Exhaust duct exit, and could easily be ported to make well over 50 Hp.
And with the PV in place it would jet past any bog RS125 out of every turn, due to the gearing enabled by the great overev.
Here is a dyno sheet ( rear wheel Hp ) of a well tuned customer Honda, a B kit, and Azuma's A kit with PV - I know what I would be trying to replicate.

321874




Yep, it would be impossible to compete against an engine that had the same power at 13800 as a well tuned stocker has at 12200.
As i say, the CR cylinder is well capable of being tuned to even above this level, is cheap and available.
Add a long 110 rod from say Samarin with a plate and you have what won the last 250GP championship.
Slap on an Ignitech, a modern fat pipe, a VF2 and you are well into the 50Hp zone cheaply with ease..


Is the famous Kiwi ingenuity is dead then? In superkarts here in Australia a friend of mine pioneered several things that are now de rigueur in superkarts. All on a humble old NF4 engine that ended up nudging 45hp. All done with off the shelf parts, no expensive " A/B/C/D kit" parts most of them we got off ebay. That engine ran rings around karts that someone spent $5000 on a NX4 rebuild. We even tested a $18 conrod from Thailand that worked a charm.
A recent race meeting on a tight track a very good rider with a CR85 engine in a NF4 frame won races outright against a NX4. Point is the humble NF4(like a RSW 125) is still a very capable bike in the right hands.


Is the famous Kiwi ingenuity is dead then? In superkarts here in Australia a friend of mine pioneered several things that are now de rigueur in superkarts. All on a humble old NF4 engine that ended up nudging 45hp. All done with off the shelf parts, no expensive " A/B/C/D kit" parts most of them we got off ebay. That engine ran rings around karts that someone spent $5000 on a NX4 rebuild. We even tested a $18 conrod from Thailand that worked a charm.
A recent race meeting on a tight track a very good rider with a CR85 engine in a NF4 frame won races outright against a NX4. Point is the humble NF4(like a RSW 125) is still a very capable bike in the right hands.


The CR125 crank parts are same same as RS125 quality wise and last forever over 12,000 rpm in a SKUSA engine.
I think Lozza has looked at putting a HotRods CR125 crank into the RS as it has higher inertia, and revs on better ?

Inlet Duct Resonance.


It may be different for reed valve engines Rob, but not that different.
In all inlet systems the inlet flow accelerates as long as the pressure upstream of the inlet tract is higher than the downstream pressure.
When both pressures are equal the flow has reached its maximum velocity and because mixture keeps entering the crankcase, the case pressure rises above the upstream pressure and this rising pressure gently slows the flow down to a standstill (or suddenly instead of gently if the inlet port closes too soon, which can happen in both piston port and rotary induction systems).
In any case, the pressure at the crankcase side of the inlet tract will then be higher than the pressure at the bellmouth, and mixture will start flowing back towards the free world. The extend of this backflow may be so small that it is not noticeable at the bellmouth, but it is happening nevertheless. Reed valves do it just as much as other inlet control systems.

I call this phenomenon bounce-back and it should not be confused with the blow-back that occurs when an inlet port closes too late.
Bounce-back mixture never really made it into the crankcase; it returned at the closed door.
Blown-back mixture initially entered the crankcase but then reversed its flow direction because of the rising case pressure before the case was closed.
This rising case pressure resulting in flow reversal has rather little to do with the piston moving down after TDC. It can even happen before TDC if the Helmholtz frequency of the inlet system is too high for the engine revs (low revs, big carb diameter, short inlet tract, small case volume).

By the way, bounce-back may be hardly noticeable, but on the other hand it can be even more vicious than blow-back.
As an experiment I once put a 200 mm elongation tube between the carb and the rotary inlet cover of a 125 cc Rotax.
It lowered the Helmholtz frequency of the inlet system so much that inlet flow velocity was still near its maximum when the inlet disc closed. Bounce-back was so severe that within seconds the dyno room was completely fogged up with mixture. It frightened me to death; a spark would have been enough to blow the roof off.

[2T Institute]

The CR125 crank parts are same same as RS125 quality wise and last forever over 12,000 rpm in a SKUSA engine.
I think Lozza has looked at putting a HotRods CR125 crank into the RS as it has higher inertia, and revs on better ?

Been running the CR crank for yonks will go to 15,000 but had to set the limiter at 14,200. Rev junkies :eek:

[Muciek]

http://www.motorcyclenews.com/sport/tt-road-races/2016/may/suter-500-iom-tt-unveiled/

Can't wait to see this racing :shit:

On the last picture You can see expansion chambers ,and they look strange at belly section where it meets diffusor and back cone.

[MotleyCrue]

http://www.motorcyclenews.com/sport/tt-road-races/2016/may/suter-500-iom-tt-unveiled/

Can't wait to see this racing :shit:

On the last picture You can see expansion chambers ,and they look strange at belly section where it meets diffusor and back cone.


Since this is a V4 and I only see two exhausts, are there 2 more exhausts I'm not seeing or does this engine have 2 cylinders per exhaust ? 195 HP using paired cylinders would be rather impressive as paired cylinder engines go .

[ief]

Under the seat

[chrisc]

http://www.motorcyclenews.com/sport/tt-road-races/2016/may/suter-500-iom-tt-unveiled/

Can't wait to see this racing :shit:

On the last picture You can see expansion chambers ,and they look strange at belly section where it meets diffusor and back cone.

No doubt there are some super high expectations being put on the Suter. I'd love to see it do well, particularly in it's first year, and bring back the interest in 2 strokes in floods. Love the quote on it's fairings "4strokes are 4grandmothers"


"We're heading over to the TT with a completely open mind because we still don't know the level of it, we're still learning it. It feels great though and it's a really good, strong package, but those superbikes are so good so it's hard to say right now where we'll finish. Basically, I'm the only one who's done any development on it. Eskil [Suter] himself rode it initially when he first unleashed the bike, then Wayne Gardner had a go on it, then Freddie Spencer, but other than that – and I didn't realise it at the time – I'm the one who's been developing it… But all that said, it wasn't like I was starting from scratch, and it was quite resolved when I first rode it. But this last test was really useful because the faster speeds picked up a few problems that we hadn't had before and we managed to sort them out, so now we're heading to the TT with a really good package."

Anyone have details about the fuel injection it's running? Throttle body injection, crank case or direct?

[wobbly]

The titanium belly weld makes an optical illusion, its just a normal parallel mid section.
Would have cost a zillion dollars to get Akrapovic to make those chambers.
The thing is a big bore, 580cc or something odd I read, so 195Hp isnt super spectacular for the size.
The other interesting ride is Anstey on Clive Padgetts Honda RCV MotoGP bike, be very surprised if that doesnt take the lap record.
Bruce can do it for sure.

[ken seeber]

All I can say is that it will sound beautiful. Absolutely. And a shitload better than a Moto3 (Mugello), which sounds like a pregnant pig with an extreme form of spluttering diarrhoea, particularly after eating 2 dozen cans of baked beans.

[Flettner]

All I can say is that it will sound beautiful. Absolutely. And a shitload better than a Moto3 (Mugello), which sounds like a pregnant pig with an extreme form of spluttering diarrhoea, particularly after eating 2 dozen cans of baked beans.
That good aye, don't hold back.

[Frits Overmars]

No doubt there are some super high expectations being put on the Suter. Anyone have details about the fuel injection it's running? Throttle body injection, crank case or direct?Shower and throttle body.

[TZ350]

321889

Interesting bell mouth injectors, I would love to know more as I did not have much success with bell mouth injectors myself. I guess because with the rotary valve there was always a rpm dependent reversion hole some place blowing the fuel out instead of sucking it in, maybe different for reed valve engines. Also interesting that the 500 has two injectors, one injector in the bell mouth and a second in the throttle body.


321887321888

Both high and low speed injectors firing into the bell mouth.

321886321890

Low speed injector firing into the bell mouth with the high speed injectors firing across the transfer ports and visa versa. Neither configuration worked that well for me.

[Frits Overmars]

Interesting bell mouth injectors, I would love to know more as I did not have much success with bell mouth injectors myself. I guess because with the rotary valve there was always a rpm dependent reversion hole some place blowing the fuel out instead of sucking it in, maybe different for reed valve engines. It may be different for reed valve engines Rob, but not that different.
In all inlet systems the inlet flow accelerates as long as the pressure upstream of the inlet tract is higher than the downstream pressure.
When both pressures are equal the flow has reached its maximum velocity and because mixture keeps entering the crankcase, the case pressure rises above the upstream pressure and this rising pressure gently slows the flow down to a standstill (or suddenly instead of gently if the inlet port closes too soon, which can happen in both piston port and rotary induction systems).
In any case, the pressure at the crankcase side of the inlet tract will then be higher than the pressure at the bellmouth, and mixture will start flowing back towards the free world. The extend of this backflow may be so small that it is not noticeable at the bellmouth, but it is happening nevertheless. Reed valves do it just as much as other inlet control systems.

I call this phenomenon bounce-back and it should not be confused with the blow-back that occurs when an inlet port closes too late.
Bounce-back mixture never really made it into the crankcase; it returned at the closed door.
Blown-back mixture initially entered the crankcase but then reversed its flow direction because of the rising case pressure before the case was closed.
This rising case pressure resulting in flow reversal has rather little to do with the piston moving down after TDC. It can even happen before TDC if the Helmholtz frequency of the inlet system is too high for the engine revs (low revs, big carb diameter, short inlet tract, small case volume).

By the way, bounce-back may be hardly noticeable, but on the other hand it can be even more vicious than blow-back.
As an experiment I once put a 200 mm elongation tube between the carb and the rotary inlet cover of a 125 cc Rotax.
It lowered the Helmholtz frequency of the inlet system so much that inlet flow velocity was still near its maximum when the inlet disc closed. Bounce-back was so severe that within seconds the dyno room was completely fogged up with mixture. It frightened me to death; a spark would have been enough to blow the roof off.

[TZ350]

Thanks Frits, great explanation.

I also see from simulations with EngMod that the airflow behaviour within the inlet tract can change over the useful rpm range.

Sometimes being completely one way for some of the rpm range, then at another rpm reversing at some point in the inlet cycle and at another rpm point completely changing direction in the inlet tract several times.

All these different inlet tract air flow scenarios can happen while the engine is making good power. And with a 6ms engine revolution, an inlet window of say 2ms and an injection cycle of 3ms, injection timing that avoids air flow bounce back or excessive wall wetting is challenging.

321896321897

Resonant behaviour in the inlet tract changes with both rpm and throttle position.

321901321900321899321898

My recent EFI efforts have been focused on trying different positions for the small injector and to map the small inlet injectors injection cycle to work with the inlet resonance.

[breezy]

It may be different for reed valve engines Rob, but not that different.
In all inlet systems the inlet flow accelerates as long as the pressure upstream of the inlet tract is higher than the downstream pressure.
When both pressures are equal the flow has reached its maximum velocity and because mixture keeps entering the crankcase, the case pressure rises above the upstream pressure and this rising pressure gently slows the flow down to a standstill (or suddenly instead of gently if the inlet port closes too soon, which can happen in both piston port and rotary induction systems).
In any case, the pressure at the crankcase side of the inlet tract will then be higher than the pressure at the bellmouth, and mixture will start flowing back towards the free world. The extend of this backflow may be so small that it is not noticeable at the bellmouth, but it is happening nevertheless. Reed valves do it just as much as other inlet control systems.

I call this phenomenon bounce-back and it should not be confused with the blow-back that occurs when an inlet port closes too late.
Bounce-back mixture never really made it into the crankcase; it returned at the closed door.
Blown-back mixture initially entered the crankcase but then reversed its flow direction because of the rising case pressure before the case was closed.
This rising case pressure resulting in flow reversal has rather little to do with the piston moving down after TDC. It can even happen before TDC if the Helmholtz frequency of the inlet system is too high for the engine revs (low revs, big carb diameter, short inlet tract, small case volume).

By the way, bounce-back may be hardly noticeable, but on the other hand it can be even more vicious than blow-back.
As an experiment I once put a 200 mm elongation tube between the carb and the rotary inlet cover of a 125 cc Rotax.
It lowered the Helmholtz frequency of the inlet system so much that inlet flow velocity was still near its maximum when the inlet disc closed. Bounce-back was so severe that within seconds the dyno room was completely fogged up with mixture. It frightened me to death; a spark would have been enough to blow the roof off.

so would allowing the inlet elongation tube to vent into another low pressure area once the rotary valve had shut stop this from happening?

[TZ350]

When I first tried the plenum it gave a dramatic boost in torque in the rpm area below the original peak torque curve. Basically it plumped up the area of the torque curve that is negatively affected by the pipe resonance working against the engine's exhaust port timing.

I guess this was a resonant effect between the size of the plenum, it's inlet and the engine's crankcase volume and inlet timing working together to prevent the pipes out of step pressure wave, pushing the fresh mixture back down the transfers, well maybe???.

The positive effect on the torque curve by the plenum was so marked that I am keen to explore it further. I have an idea that a two chambered plenum could work, one for this torque boosting resonance and a butterfly that opens to another chamber when a different plenum volume is required. Or maybe a variable length inlet runner, or combination of both.

321919321920

But first, to be able to use a plenum without the fuel dropout issues that you get with an outside the plenum carb, I have to perfect the EFI system. If I can't do that I will look at putting the carb inside the plenum itself and feed it with a pump around bypass fuel system like they use on Karts.

[Frits Overmars]

so would allowing the inlet elongation tube to vent into another low pressure area once the rotary valve had shut stop this from happening?Yes, you could connect a boost bottle to the inlet tract, directly upstream of the inlet disc. But what good would it do? It would only swallow mixture that should have been entering the crankcase in the first place, but that didn't make it because the inlet closed too early.
The long column of mixture in the elongation tube has a lot of inertia which means that it is reluctant to start flowing towards the crankcase. And once it is on the move, it should be allowed to continue filling the crankcase as long as the flow direction is positive, which in turn means that a long inlet tract also requires a long inlet timing. You don't want that because at certain revs it will give a lot of blow-back. Keeping the inlet tract and the inlet timing short will result in a forgiving easy-to-jet engine.

Don't worry about harnessing the pulses in the inlet tract; it would require a tract length of about two/thirds the length of the complete exhaust system (two/thirds because of the lower speed of sound in cold mixture versus hot exhaust gases). In an inlet tract (and even more so in transfer ducts) the pulses are reflected to and fro so many times that they have lost most of their energy by the time they could finally do something good. Bottom line: keep the inlet tract short.

[breezy]

Yes, you could connect a boost bottle to the inlet tract, directly upstream of the inlet disc. But what good would it do? It would only swallow mixture that should have been entering the crankcase in the first place, but that didn't make it because the inlet closed too early.
The long column of mixture in the elongation tube has a lot of inertia which means that it is reluctant to start flowing towards the crankcase. And once it is on the move, it should be allowed to continue filling the crankcase as long as the flow direction is positive, which in turn means that a long inlet tract also requires a long inlet timing. You don't want that because at certain revs it will give a lot of blow-back. Keeping the inlet tract and the inlet timing short will result in a forgiving easy-to-jet engine.

Don't worry about harnessing the pulses in the inlet tract; it would require a tract length of about two/thirds the length of the complete exhaust system (two/thirds because of the lower speed of sound in cold mixture versus hot exhaust gases). In an inlet tract (and even more so in transfer ducts) the pulses are reflected to and fro so many times that they have lost most of their energy by the time they could finally do something good. Bottom line: keep the inlet tract short.

but once the door is shut on the crankcase couldnt another door be opend into an area of low pressure to keep the fuel flow continuous...? doesnt the cylinder pressure fall as the exhaust port opens?

[Frits Overmars]

but once the door is shut on the crankcase couldnt another door be opend into an area of low pressure to keep the fuel flow continuous...? doesnt the cylinder pressure fall as the exhaust port opens?Sure, you could open a door to the outside world but that would be wasting fuel. Or can you imagine another area of low pressure at say 80° after Top Dead Center?
True, the cylinder pressure falls as soon as the exhaust port opens. But it will take another 40° or so crank degrees before the cylinder pressure has fallen below the normal bounce pressure that was generated at the closing inlet port, assuming that the inlet port timing matches the inlet flow.
This bounce pressure equals the crankcase pressure at the moment of inlet closure. But then the crankcase pressure is raised a bit further by the descending piston while the bounce pressure fades away.
Only if the inlet closes too early, the bounce pressure will be higher than the crankcase pressure. But why would you want to open a door to another area of low pressure (if we could find such an area) when it is so much simpler to keep the inlet door open until the flow velocity has slowed down to zero?

[TZ350]

... once the door is shut on the crankcase couldnt another door be opend ...

Some of the other doors I have tried.

321921321922

Expansion chamber pressure bleeder. Red line = Open.

321924321923

Increased crankcase volume. Red line = extra volume.

321926321925

Variable inlet timing +/- 15 deg. Blue line = -15deg

[TZ350]

321927321928

24 and 30mm carburettors in back to back test. Blue line = 30mm

321930321929

Divider in an angled inlet manifold. Blue line = divider.

321934321933

Tillotson HL360A 24mm pumper carb. Blue line = 28 rwhp.

[TZ350]

321936321935

The 12rwhp Suzuki GP125 where it all began, Blue line, with a bit of tuning and all the bits and bobs = 31rwhp.

321937321938321939321940

The pistons bridge oiling holes can be sealed with devcon, it lasts. Extra copper cooling fin that is also the squish band. Large 32mm inlet for the Suzuki GP and a drill press makes a handy porting tool.

[richban]

I have been playing around with the exhaust port on the 300 cylinders. I have added some side angle to the port. Not much as the casting is very thin there and could easy pop out into the water jacket. But some has got to be better than the none it has.

321776



Turns out some, is 100% better than none when it comes to exhaust port side angle area. I made 2 changes to the bike. Bigger stinger and exhaust port change = 6 more hp peak way less heat and more power and toque everywhere. Can't wait to ride it. There is still more to come from some pipes that wob has kindly designed. A lot more! Also Engmod is bang on with the predictions.

[TZ350]

Good work Rich, looking forward to an on the track performance report.

[Flettner]

321889

Interesting bell mouth injectors, I would love to know more as I did not have much success with bell mouth injectors myself. I guess because with the rotary valve there was always a rpm dependent reversion hole some place blowing the fuel out instead of sucking it in, maybe different for reed valve engines. Also interesting that the 500 has two injectors, one injector in the bell mouth and a second in the throttle body.


321887321888

Both high and low speed injectors firing into the bell mouth.

321886321890

Low speed injector firing into the bell mouth with the high speed injectors firing across the transfer ports and visa versa. Neither configuration worked that well for me.http://i1056.photobucket.com/albums/t380/uniflow/th_f9_zps30a41b19.mp4 (http://i1056.photobucket.com/albums/t380/uniflow/f9_zps30a41b19.mp4)

An old piece of (poor) video, the F9 when first set up with EFI and the ball valve. RV slide is also installed and operating here.

Husa, help, I've installed the video wrong? I think. I guess I'm just showing the ball valve at work, if only free running.

[husaberg]

http://i1056.photobucket.com/albums/t380/uniflow/th_f9_zps30a41b19.mp4 (http://i1056.photobucket.com/albums/t380/uniflow/f9_zps30a41b19.mp4)

An old piece of (poor) video, the F9 when first set up with EFI and the ball valve. RV slide is also installed and operating here.

Husa, help, I've installed the video wrong? I think. I guess I'm just showing the ball valve at work, if only free running.

I am not finding it
oh wait I did
http://i1056.photobucket.com/albums/t380/uniflow/th_f9_zps30a41b19.mp4 (http://i1056.photobucket.com/albums/t380/uniflow/f9_zps30a41b19.mp4)

http://vid1056.photobucket.com/albums/t380/uniflow/f9_zps30a41b19.mp4

here are most of your videos
https://www.youtube.com/user/GerbilGronk/videos?sort=dd&shelf_id=1&view=0
https://www.youtube.com/channel/UCeSb-yZg5B1bDRW2iuXe25Q

[chrisc]

Unsure if anyone would be able to see these but a mate just posted some good shots of the Suter 500 on facebook:

https://www.facebook.com/seth.devereux/media_set?set=a.10209023570721859.1073741841.10951 23468&type=3

[breezy]

When I first tried the plenum it gave a dramatic boost in torque in the rpm area below the original peak torque curve. Basically it plumped up the area of the torque curve that is negatively affected by the pipe resonance working against the engine's exhaust port timing.

I guess this was a resonant effect between the size of the plenum, it's inlet and the engine's crankcase volume and inlet timing working together to prevent the pipes out of step pressure wave, pushing the fresh mixture back down the transfers, well maybe???.

The positive effect on the torque curve by the plenum was so marked that I am keen to explore it further. I have an idea that a two chambered plenum could work, one for this torque boosting resonance and a butterfly that opens to another chamber when a different plenum volume is required. Or maybe a variable length inlet runner, or combination of both.

321919321920

But first, to be able to use a plenum without the fuel drop-out issues that you get with an outside the plenum carb, I have to perfect the EFI system. If I can't do that I will look at putting the carb inside the plenum itself and feed it with a pump around bypass fuel system like they use on Karts.

so the fuel drop- out is caused by the fuel becoming stationary within the plenum?would having some kind of turbulence within the plenum keep it homogenised, or even being able to keep the fuel/air mixture circulating somehow , somwhere?

[Tim Ey]

Unsure if anyone would be able to see these but a mate just posted some good shots of the Suter 500 on facebook:

https://www.facebook.com/seth.devereux/media_set?set=a.10209023570721859.1073741841.10951 23468&type=3

Does anyone know a stream / internetplatform where I may watch the Suter racing on the Isle of man this evening? :corn:

[dark art]

Does anyone know a stream / internetplatform where I may watch the Suter racing on the Isle of man this evening? :corn:

IOMTT website says that most coverage come from itv4. Superbike and senior will be at 4 june.

http://www.iomtt.com/TT-Info/The-TT-on-TV.aspx


Of course, after a few days youtube and facebook will be full of it.

[Muciek]

https://twitter.com/drobinson97/status/737540889879285760It looks like they have some problem with setup of bike
57 21 Ian Lougher Suter/Suter Racing Technology 2 19:29.388 116.153 (Last year Anstey managed to do 126mph lap on 1992 YZR500)

But that sound :eek:

[haan]

Hi all together

I´m new here and just amazed about the knowledge and experience shared in this Topic.
I´m happy to learn a lot more again.

Maybe you can help me if there is a talk about dyno graphs and their interpretation,what has to be changed to get a better curve.

Thanks in advance

Bye JOchen

[TZ350]

Isotropic Polishing.

A short extract from a University study into Isotrop Polishing that explains the process.

322020

Isotropic polishing. https://www.facebook.com/<wbr>SuperFinishingLtd/ (https://www.facebook.com/SuperFinishingLtd/)

I always wondered if Isotropic polishing was snake oil, but now I am a believer. In short, a normal polishing method would remove material, but Isotropic polishing is a material exchange process.

322021322022 before and after Isotropic polishing.

So you wind up with a shiny thing that is still dimensionally the same size as it was. I was particularly interested in how the process would affect the tungsten and alloy plugs in my crankshaft and what the finish on the oil seal surface would look like.

Isotropic polishing can be applied to dimensionally critical surfaces like the big end bearing surface in a 2T connecting rod and pin.

As I understand it, bearing surfaces are a ground finished with a fine but distressed layer at the surface, same with gears. Isotropic polishing being an exchange process both removes and replaces this distressed layer with a smooth and finely polished layer. This smooth finish noticeably reduces friction between the sliding surfaces.

Anyway it can be done locally here in Auckland:- Isotropic polishing. https://www.facebook.com/<wbr>SuperFinishingLtd/ (https://www.facebook.com/SuperFinishingLtd/)

[TZ350]

Help

322023

Help, I am unable to make new posts or reply to other people's posts in the normal way on this thread. I can do everything in the normal way on other threads but not this one. I can't just select "Reply to Thread" or Reply with Quote" and start entering text like is normal. I first have to do a work around which is post a picture and without left clicking the mouse inside the edit screen, just randomly enter text then save it. After that little palva I can then go back and Edit the Post and enter the text I wanted to.

Help help......

[Ocean1]

Help

322023

Help, I am unable to make new posts or reply to other people's posts in the normal way on this thread. I can do everything in the normal way on other threads but not this one. I can't just select "Reply to Thread" or Reply with Quote" and start entering text like is normal. I first have to do a work around which is post a picture and without left clicking the mouse inside the edit screen, just randomly enter text then save it. After that little palva I can then go back and Edit the Post and enter the text I wanted to.

Help help......

Testing....

...Looks like it's your end mate.

[TZ350]

322026

Wob PM'ed me, that he is having the same issues.

[mr bucketracer]

The end of the world is near lol

[RAW]

Yes, you could connect a boost bottle to the inlet tract, directly upstream of the inlet disc. But what good would it do? It would only swallow mixture that should have been entering the crankcase in the first place, but that didn't make it because the inlet closed too early.
The long column of mixture in the elongation tube has a lot of inertia which means that it is reluctant to start flowing towards the crankcase. And once it is on the move, it should be allowed to continue filling the crankcase as long as the flow direction is positive, which in turn means that a long inlet tract also requires a long inlet timing. You don't want that because at certain revs it will give a lot of blow-back. Keeping the inlet tract and the inlet timing short will result in a forgiving easy-to-jet engine.

Don't worry about harnessing the pulses in the inlet tract; it would require a tract length of about two/thirds the length of the complete exhaust system (two/thirds because of the lower speed of sound in cold mixture versus hot exhaust gases). In an inlet tract (and even more so in transfer ducts) the pulses are reflected to and fro so many times that they have lost most of their energy by the time they could finally do something good. Bottom line: keep the inlet tract short.

Frits is it possible to have to short of a inlet tract for a disc valve engine ?
If so would you explain the issues, complications & tell tail signs please.

[Mental Trousers]

Help

322023

Help, I am unable to make new posts or reply to other people's posts in the normal way on this thread. I can do everything in the normal way on other threads but not this one. I can't just select "Reply to Thread" or Reply with Quote" and start entering text like is normal. I first have to do a work around which is post a picture and without left clicking the mouse inside the edit screen, just randomly enter text then save it. After that little palva I can then go back and Edit the Post and enter the text I wanted to.

Help help......

Ok. Issue is there's an iframe that gets dropped over top of the page when you try to edit things. So when you click to try and type stuff in you're (unknowingly) clicking and typing in the iframe.

Somebodies gone and posting bollocks and messed things up I think. Not cool.

[Mental Trousers]

Ok. Issue is there's an iframe that gets dropped over top of the page when you try to edit things. So when you click to try and type stuff in you're (unknowingly) clicking and typing in the iframe.

Somebodies gone and posting bollocks and messed things up I think. Not cool.

Problem fixed.

[TZ350]

Problem fixed.
So it is, many thanks. TeeZee

[teriks]

Frits is it possible to have to short of a inlet tract for a disc valve engine ?
If so would you explain the issues, complications & tell tail signs please.

Not Frits, not a disc (but still a rotary valve) and on a different scale from your normal bike engine but anyway:

Black line: Inlet tract as short as physically possible, timings optimized for this.
Red line: Longer inlet tract, same timings as above, inlet bell identical to above.

322066

Now, this is with a rotary drum valve with potential for huge STA with moderate timing on an engine without throttle ans stuff that adds to the practical minimum length, but still, it seems possible to have a too short inlet tract.

EDIT: A bit surprising was that further tries to optimize the timings for the new (longer) inlet tract didn't result in any improvements at all.

[Frits Overmars]

Frits is it possible to have to short of a inlet tract for a disc valve engine ?
If so would you explain the issues, complications & tell tail signs please.You'll need a bellmouth for any inlet system, so the air that is flowing in from the sides, is gently guided into the desired flow direction instead of crossing up the flow and causing a restriction. Compare it to a crowd of people trying to leave a hall. The people coming from the sides disturb the progress of the people that are moving towards the exit in a straigth line. It's the same with molecules.
So the bellmouth is necessary and it has to have some length in orfer to accommodate a decent radius. Apart from that, the shorter the inlet tract, the less inertia of the mixture in the tract, the better it will accelerate and the quicker it will fill the crankcase.
If the revs are too low, or the inlet timing too long, or the inlet diameter too big, or the tract too short, you will have backflow before the inlet closes.
But don't blame the short tract; blame the inlet timing, or blame the rider who fails to rev the engine.

[teriks]

So the bellmouth is necessary and it has to have some length in orfer to accommodate a decent radius. Apart from that, the shorter the inlet tract, the less inertia of the mixture in the tract, the better it will accelerate and the quicker it will fill the crankcase.

Thats my understanding as well, and the reason I put quite some effort into designing the inlet tract as short as possible on my (not yet finished) rear intake version of the MB LS.

It seems that EngMod dont agree that a shorter tract is better in every case though.
After finding the minimum length as per above, I did a shit load of simulations of different opening and closing timings before deciding on what seemed optimal.
After that I tried lengthening the tract, and ended up with the "more power everywhere" curve above. -I could not get anything near that with the short tract, no matter what timings I tested.
The bellmouth below was used as is on both the long and short version, only the length of cone after the short cylindrical section was changed.
322067
Granted it might be a fluke in the simulation, but Ill try both versions eventually.

[wobbly]

Well I am back - sorry to say.
I was originally trying to make some snide comments about the Suter effort being a bloody expensive joke.
Why anyone would go to the IOM with an engine that obviously hasnt been dynoed to death, and for the engineer (s) to think that they
are suddenly the only ones in the world who are capable of making throttle body injection work on a racing two stroke at part throttle ( as NO ONE has been able to
make that work properly yet ) gives us an insight as to why Kalex have blown the Suter completely off the GP2 track.

They have the most expensive, and superbly built pipes ( done by Akrapovic ) who have never made 2T pipes before ( so you have to ask who designed them )
and the only comment we hear is that " its got a fueling issue " well no shit, they should have paid TeeZee to have a go at the computer as he would have more idea
about the problems than anyone at Suter.

And the last straw was we are told it fouled a plug in the race - when was the last time that happened in any form of 2T racing since 1960 something.
I suppose they were running those real expensive BR9ES lawnmower things.
Yes I am pissed off with them, and no I dont think I could have done any better, as I for sure wouldn't have even tried that dumb a stunt in public.

PS - Teriks, have you tried modelling the bell as 3 sections to increase the accuracy over a simple straight line ?

[F5 Dave]

Soooooo. . . What was the guts of Itoh's NSR500 that was reputedly tested with injection in the late 90s? Obviously it didn't work better than carbs so not progressed but not much info besides journalists guesses. Think I read it wasn't injected after all years later but it clocked the highest speed at the time. Do we know any more?

[1948rod]

hi wobbly if you have the time could you point out the developement areas that have evolved over the last few years in kz kart engines. you have been jonny on the spot to be well informed to show the masses what direction they have changed. these engines even with their constraints are still going ahead. thanks for sharing the knowledge.

[husaberg]

Soooooo. . . What was the guts of Itoh's NSR500 that was reputedly tested with injection in the late 90s? Obviously it didn't work better than carbs so not progressed but not much info besides journalists guesses. Think I read it wasn't injected after all years later but it clocked the highest speed at the time. Do we know any more?

Itoh did a full year on the injected bike in about 95 but his best result that year was using Doohans bike in one race when Doohan was injured or something
The injected bike did have the fastest speedtrap that year, but itoh could tuck in better than Mick anyway.
Mick tested it but refused to race it.... as he wanted to win the championship.
I will post the guff I have.
it was throttle body injection as far as I know.
As you see Honda was doing it for fuel consumption.
they had also trialled it earlier in both 250 and 500 form

[husaberg]

the rest..........
The fuel injection and carburated version of both the big bang and another version (that was never used) occurred in winter testing in Aussie 1992.
According to Yoichi Oguma they asked the riders to decide and they said there was at the time no point in changing over to fuel injection "as it gave no real advantage"
All the reports I have read had Itoh using the Fuel injected bike for most of 1993 season.
Cagiva according Goggi to them started testing fuel injection in 1988.

[wobbly]

Itohs injected Honda held the fastest speed trap number for quite a long time, but I have it from several people that this bike
was only used in practice - it was never actually raced.
Doohans reaction was reminiscent of Foggys about the injected Cagiva " its a piece of shit and I wouldnt ride it no matter how much you pay me ".
I have read the SAE papers on the system, and the Honda ECU ran on a bunch of lookup tables in closed loop that were sequenced to diagnose and then rectify any misfire.
Honda felt that the sensors of the time were not reliable enough to run in open loop, continuously changing a single base map for fueling and or ignition.

I will reply about KZ2 tomorrow.

[teriks]

PS - Teriks, have you tried modelling the bell as 3 sections to increase the accuracy over a simple straight line ?
Almost, in my current model the bell is divided in five sections + end correction.
Not very good for run-time, but the results differ slightly from the single straight line.

[Flettner]

This fuel injection debate/talk interests me, am I so wrong? Can you see why throttle body injection in a twostroke is doing things the hard way? It's all about homogeneous charge, can you see that at lower RPM's (using PULSED injection) there is just a small 'pocket' of fuel dispenced into the incoming air. The crank case is not 100% pump so not all of this fuel pocket will neccessarily go up into the cylinder each cycle. So you get inconsistent fueling up into the cylinder (at part throttles) = bad/gutless engine response, sharp power band as this problem starts to come right as the injection time gets longer. Having a small injector then onto a large injector is a patch up and has it's own problems. I can only say (again) that transfer port injection is a much better solution, with (timed right) ALL the fuel injected each cycle being transfered to the cylinder.
When I do my next injection system I'll be injecting across the inlets of the transfers in the crank case, from front to back. Not interested in fuel consumption just homogeneous charge (or best I can get), with timing being critical. This will be nessasary as there will be no throttle body at all, throttling will be done at the transfers.
I ride my shitty old Kawasaki around every evening just before dark, just to scare myself, perhaps I better tell it not to run so well, not being throttle body injected and all. :facepalm:

[wobbly]

KZ2 engines as far as factory development is concerned over the last few years is confined to a few detail areas.
The main one has been to tilt the cylinder back and at the same time straighten out the inlet tract, ending up with no
bend at all at the manifold and thus the carb pointing seriously downward.
This allows the reed block to point upward under the piston, and the straight manifold rubber has, at the same time been shortened as much as is physically possible.
Now the thin rubber flange sits hard against the reed block face, with just enough room to get a thin hose clamp onto the carb spigot.
This straight shot has made redundant all the years of hard work put into staggering the reed thickness, and backup tension, to try and redistribute the
flow more evenly thru all the petals.
Thus the reeds are now the same top and bottom in all the fastest engines I have dynoed.
As the inlet is straight, the flow is even in all directions, and power has increased by around 1.5 to 2 Hp from just this and the shortened tract length.
Most engines have also been progressively reduced in the Exh duct exit area, and some now have proper oval to round transitions in the slip joint
manifold with no steps at the face.

High inertia cranks are now the norm, but were "specials " a few years ago.
Pipe development has stalled for some time, as all are out at around 130 diameter, and the last TM homologation just made the TL around 6mm shorter
but very little variation in tapers.
Ports have also been pretty much locked in for years, all with normal stagger, just varying amounts of it.
I have concentrated on small areas of development, working on the cooling of the head and the Ex duct, along with the allowed fiddling with stingers/mufflers.
and the Ex spigot ( you can shorten the pipe legally on older engines simply by machining off the spigot mounting faces ).

There is still a huge amount of detail design work that hasnt even filtered down from the end of 2T GP racing years ago, and from the results of a large amount of
( currently illegal ) dyno work I have done, I have scored the best 2T tuning job in the world.
As after the World Finals in Vegas I am off to Pesaro to work at the TM factory with Franco Drudi on the next homologation design.

So ask me the same question next year.

[2T Institute]

This fuel injection debate/talk interests me, am I so wrong? Can you see why throttle body injection in a twostroke is doing things the hard way? It's all about homogeneous charge, can you see that at lower RPM's (using PULSED injection) there is just a small 'pocket' of fuel dispenced into the incoming air. The crank case is not 100% pump so not all of this fuel pocket will neccessarily go up into the cylinder each cycle. So you get inconsistent fueling up into the cylinder (at part throttles) = bad/gutless engine response, sharp power band as this problem starts to come right as the injection time gets longer. Having a small injector then onto a large injector is a patch up and has it's own problems. I can only say (again) that transfer port injection is a much better solution, with (timed right) ALL the fuel injected each cycle being transfered to the cylinder.
When I do my next injection system I'll be injecting across the inlets of the transfers in the crank case, from front to back. Not interested in fuel consumption just homogeneous charge (or best I can get), with timing being critical. This will be nessasary as there will be no throttle body at all, throttling will be done at the transfers.
I ride my shitty old Kawasaki around every evening just before dark, just to scare myself, perhaps I better tell it not to run so well, not being throttle body injected and all. :facepalm:

But when the best riders in the world jump on a bike and say "fueling is shit" then what is the engineer to do? Top flight professional riders have specific demands and not giving them what they ask for means the serious money factories pay them amounts to nought. An old Big Horn can only be ridden so fast by a bloke in shorts :laugh: :laugh:

[Flettner]

But when the best riders in the world jump on a bike and say "fueling is shit" then what is the engineer to do? Top flight professional riders have specific demands and not giving them what they ask for means the serious money factories pay them amounts to nought. An old Big Horn can only be ridden so fast by a bloke in shorts :laugh: :laugh:

No, even the shorts guy is too scared to hold it at full throttle. Probably more to do with the handling than anything else:eek:
I must say though, those shocks you recommended work real well (as best they can under the circumstances).

[Frits Overmars]

I have scored the best 2T tuning job in the world. As after the World Finals in Vegas I am off to Pesaro to work at the TM factory with Franco Drudi on the next homologation design.That is great news Wob :niceone:. You'll be just 1400 km away then instead of 19000 km. Hope to meet you there.

[Flettner]

I have scored the best 2T tuning job in the world.
As after the World Finals in Vegas I am off to Pesaro to work at the TM factory with Franco Drudi on the next homologation design.

So ask me the same question next year.

So, great, now we will have You AND Franco posting on ESE :niceone:
We won't tell anyone, we can keep secrets:msn-wink:
I'm assuming you won't be Wrighting us off. :laugh:
Good on you.

[teriks]

Mainly for Lightbulb, but anyway, might be of interest for someone else.

Work in slow progress, the crankcase for a rear intake version of the MB LS in the foreground. Behind it the standard front intake MB Profi.
322173

PS: Congratulations Wobbly!

[Martin1981]

I am off to Pesaro to work at the TM factory with Franco Drudi on the next homologation design.



Congrats Wob! Maybe after the Work at TM is done you could help the Ryger Guys with their next Homologation Design.

[seattle smitty]

David Vizard (okay, yes, a four-stroke guy) got to wondering about shapes of add-on carburetor bell-mouths, and wondering if the favored shapes had more to do with pleasing the eye of the engine-builder than pleasing the engine, much as fishing lures may sell well because they look good to fishermen, though maybe not to fish.

Vizard tested a range of half dozen shapes, and you might be surprised at what worked best (not a bell mouth). The lovely cast aluminum trumpets I got out of Japan to go on some little Bings turn out to be nothing special, nor does the shorty plastic version (though each did have their own slight effect). See his book, "How to Build Horsepower, Vol 2, Carburetors and Intake Manifolds."

Be aware that the testing was in still air, so you might have to build a shield to keep any erratically turbulent wind blast from messing up airflow. Maybe this is not so much of an issue with most bikes, but in retrospect (decades worth!!) I think it probably messed with my racing outboards significantly. Who was it that suggested that the 2-stroke racers' universal symbol for T-shirts and hats ought to be a piston with a big skid mark down the side?

Too soon old, too late smart. If only I had access in the Sixties and early Seventies to all the huge volume of great info that's now available in print and on-line! Young racers have no idea how different the information situation was then. I remember sitting in the Univ. of Washington Engineering library (and I was majoring in History, long story) in 1966, reading a book on high speed 2-stroke DIESEL engines by some old German, hoping to find some clues. Maybe eight or nine years later, when Gordon Jennings' little red 2-stroke book came out, we felt like Moses receiving the golden tablets!! Of course, it would have helped if I had had some brains of my own then (hardly matters now).