ESE's works engine tuner

[TZ350]

Is that a crack in your cases above the inlet port? Lower right picture, right side.

Hi Haufen, I can't see in the picture where you mean, but will have a very good look at the cylinder when I get back to the workshop.

[TZ350]

I reckon we still had it too lean.

Looks like you are right ..... 150main next????

[TZ350]

I have a few RGV250 cylinders stacked away.


Rule 24.2 3 F4 2 stroke max capacity for rebored engines 104cc
F4 4 stroke max capacity for rebored engines 158.09cc (note this was initially 130.5cc the 145cc then 150cc previously)

So to be fair, it should be 158.09 cc four strokes vs 113.82 cc 2 strokes of unlimited carb size.


To be really fair to old farts like me, it should be 125cc (actually 137cc to allow for max oversize re bores) LC and unlimited carb.

OK I would settle for 125+cc water cooled but still 24mm carb restricted.

I mean come on now, I ask you, how much hp could someone make with a restrictive 24mm's, it couldn't be much.

..... 125+cc LC and 24mm max, now that would be fair ... true ..... http://www.kiwibiker.co.nz/forums/images/smilies/yes.gif

[cotswold]

I have a few RGV250 cylinders stacked away.



To be really fair to old farts like me, it should be 125cc (actually 137cc to allow for max oversize re bores) LC and unlimited carb.

..... now that would be fair ... true ..... :yes:

Cagiva mito :yes:

[TZ350]

Cagiva mito :yes:

I think I have a cylinder somewhere.

[Haufen]

Hi Haufen, I can't see in the picture where you mean, but will have a very good look at the cylinder when I get back to the workshop.

No problem, I marked the area for you. The picture might be deceiving, but the area above the inlet port could be kind of a weak spot on side rotary engines.

[husaberg]

Devcon lip

[TZ350]

Devcon lip

Very close.


The picture might be deceiving, but the area above the inlet port could be kind of a weak spot on side rotary engines.

Well spotted, it is a crack, well sort of, some devcon that I used to fill an earlier stuff up is starting to pull away.

Thanks for spotting it.

[Grumph]

Hus - it's all very well to pull out these old articles about equating 2 vs 4 strokes, but....you really should pull up the period responses as well.
At the time their findings were not accepted either by the FIM or by the factories. Some very clued up engineers went into print decrying their findings. Since then both types of motor have moved on and if anyone looked at it now it would have to be using a totally different set of criteria.

At present I see no need to change anything but if you wish it to be discussed, go through a club and by all means try a remit....

I've watched a lot of formula changes in various branches of motorsport and it's rare here that capacity is reduced in any class...but if I had to suggest a change just possibly the 85cc watercooled MXer's run with a spec carb and pipe could be worth a look.
Whatever is done it should not obsolete existing machinery..

BTW - met Hans VD Marwitz when he came out to oversee the Britten record attempts - nice guy. Dead now....

[husaberg]

Hus - it's all very well to pull out these old articles about equating 2 vs 4 strokes, but....you really should pull up the period responses as well.
At the time their findings were not accepted either by the FIM or by the factories. Some very clued up engineers went into print decrying their findings. Since then both types of motor have moved on and if anyone looked at it now it would have to be using a totally different set of criteria.

At present I see no need to change anything but if you wish it to be discussed, go through a club and by all means try a remit....

I've watched a lot of formula changes in various branches of motorsport and it's rare here that capacity is reduced in any class...but if I had to suggest a change just possibly the 85cc watercooled MXer's run with a spec carb and pipe could be worth a look.
Whatever is done it should not obsolete existing machinery..

BTW - met Hans VD Marwitz when he came out to oversee the Britten record attempts - nice guy. Dead now....

Did you read it...... it was accepted by the FIM then because of Suzuki and Kawasakis threatening to pull out it was then and only then taken out.......... the maths is hard to argue with..... esp if one of the guys is dead now............
Simple fact the FIM comissioned them to do it they did it they a few cry babies threw there toys out of the cot the formula is pretty much spot on unless you have a better one.
buckets started as F4 104cc 2 strokes 130.5cc fours strokes
then it was 140cc four strokes
then 145cc fours strokes
then 150cc four strokes
now 158cc four strokes
Now you says the rules shouldn't be altered for a few cc to suit an oversize piston please Greg it less cc then the first change made to suit the four strokes.
i are quite happy to post the period rhetoric but i don't have any...........do you............????????????????? email i will post em.........
not interested in MX motors so please stop clouding the argument with them. its a totally separate issue all together:yes:

[Buddha#81]

I'm finding the 80cc debate interesting.......it would have been good to see Sketchy's project get off the ground as a benchmark. I probally wasnt the only one to have a look at Tardme.......$500-750 for a shitter MX bike, $300-400 for a motor freshen, sell the roller for parts. That makes a competitive motor for $1kish so bang for bucks it got to be a way to allow the class to grow and you dont have to be a 2t guru to make it happen. I'd look at doing it for my boy to start racing on as a step up from the RS50. Hell some 17's in the MX frame and it could be a weapon for Kart Tracks.

[TZ350]

... not interested in MX motors ...

Me neither

I feel that in F4 & F5 if anyone wants hp, they should make it the old school way otherwise there are plenty of std FXR's.

[Kickaha]

buckets started as F4 104cc 2 strokes 130.5cc fours strokes
then it was 140cc four strokes
then 145cc fours strokes
then 150cc four strokes
now 158cc four strokes


I didn't think they were ever offically 145cc although people were running the GL145

[Sketchy_Racer]

Me neither

I feel that in F4 & F5 if anyone wants hp, they should make it the old school way otherwise there are plenty of std FXR's.

As opposed to 80cc derbi motors? ;)

I still feel that 80cc mx motors would make a big appearance and if ruling governed them to a "stock" 20hp level that is what I would be running while the 40HP supercharger bike is finsihed :yes:

[crazy man]

As opposed to 80cc derbi motors? ;)

I still feel that 80cc mx motors would make a big appearance and if ruling governed them to a "stock" 20hp level that is what I would be running while the 40HP supercharger bike is finsihed :yes:you will need 40 hp to help learn you how to get of the mark(-; lol

[speedpro]

Personally I don't see a problem with the basic idea of running an mx80. Standard they only make 20ish hp. Once freshened up they should be reasonably economical to run. Possibly even the 85s as well. The way they make power would be the interesting thing rather than how much power they make. Could be a reliable fastish option for the people who aren't fond of the dark side. Possibly keep them stock apart from the pipe. They'd probably fit nicely into a RS chassis as well. Cost to purchase and rebuild in comparison to stuff we run now would be interesting.

[Sketchy_Racer]

you will need 40 hp to help learn you how to get of the mark(-; lol

Don't have to get off the mark with 40hp, I'll still drag race everyone to the line haha.


Personally I don't see a problem with the basic idea of running an mx80. Standard they only make 20ish hp. Once freshened up they should be reasonably economical to run. Possibly even the 85s as well. The way they make power would be the interesting thing rather than how much power they make. Could be a reliable fastish option for the people who aren't fond of the dark side. Possibly keep them stock apart from the pipe. They'd probably fit nicely into a RS chassis as well. Cost to purchase and rebuild in comparison to stuff we run now would be interesting.

Yeah my idea is that they reliable,and parts are easily obtainable. If power levels are governed to 20hp its not going to make anyones hot rod motor that they have worked hard to build redundant, I feel it will just add more riders to the battle at the front, because with the people out there now, unless you have 20hp you may as well go home if you want to try win.

For what it is worth, a piston kit is $99 and will be at your door the next day (www.motocrossparts.co.nz)

[TZ350]

... mx80. Standard they only make 20ish hp.

Took me 3-4 years to start making 20ish hp.


80cc derbi motors? ;)

And what flaver of source do you want me to swallow with that dead rat sir.

[richban]

Stock CRF150R motors are about 20. You would have to let them in to.

[Sketchy_Racer]

And what flaver of source do you want me to swallow with that dead rat sir.

I don't quite understand this comment but please know I wasn't meaning to be rude before, just a little tongue in cheek. :)


Stock CRF150R motors are about 20. You would have to let them in to.

Go away Rich, no one wants your 4 stroke rubbish... :nya:

[jasonu]

Stock CRF150R motors are about 20. You would have to let them in to.

Yeah I thought that too. Maybe pre 1990 (or so) up to 85mxr's with stock carbs??? Certainly imposing a HP limit would be totally impractable to enforce.
Is it really necessary to change the eligability rules of a class that is already very well subscribed? The only change that has been mentioned in the last page or 2 of this thread that I think is worth considering is allowing a couple of cc's more to the watercooled 100's purely to allow more accessable piston/rings and that is only if it is true that the MB, RG400, TF100 etc pistons are no longer available.

[Kickaha]

Must be just me but I cant see why people seem to be trying to fix a class that isn't broken

[Sketchy_Racer]

Yeah I thought that too. Maybe pre 1990 (or so) up to 85mxr's with stock carbs??? Certainly imposing a HP limit would be totally impractable to enforce.
Is it really necessary to change the eligability rules of a class that is already very well subscribed? The only change that has been mentioned in the last page or 2 of this thread that I think is worth considering is allowing a couple of cc's more to the watercooled 100's purely to allow more accessable piston/rings and that is only if it is true that the MB, RG400, TF100 etc pistons are no longer available.

I agree with this, the rules don't need to be changed, there is nothing to fix, I just want a fast reliable two stroke to beat Richban with but I really want a two stroke motor that isn't 20 years old and isn't going to cost me more than a entire MX bike to buy just a motor.

Change the rules at least to allow KT pistons in MBs etc. I ran mine over size for a couple rounds illegally but I did a shit job of it and was slower and seized once a day minimum with the KT piston.

[Sketchy_Racer]

Must be just me but I cant see why people seem to be trying to fix a class that isn't broken

That's the point, it's not broken so we must work on changing things until it doesn't work. That is what I have learnt in the engineering world, I assume it applies to everything??

[TZ350]

... mx80. Standard they only make 20ish hp. Possibly keep them stock apart from the pipe. They'd probably fit nicely into a RS chassis as well.

I have a KX80 engine in the shed and an RS125 chasis. Now lets see, the MX80 and 85 already have a bigger carb than I am currently allowed, they are water cooled, six speed close ratio and have well developed inlet, transfer and exhaust ports plus blowdown STA to spare so no need to modify the ports, all thats required is a little freshen up, and thats easily done by the shop, so all good there. And in keeping with the lazy spirit of not doing any of it ourselves we could pay someone like Wob to make the pipe. So with a little dosh and no nouse the possibilities are 30+rwhp with little effort.

[Farmaken]

Why not let them have their KT pistons & 112cc :yes:







And a 24mm carb to go with it all :girlfight:

[jasonu]

Why not let them have their KT pistons & 112cc :yes:







And a 24mm carb to go with all :girlfight:

Because then ESE will ask for 135cc and the coal burners will want 165cc. Where will it end???
The Bucket formula seems to be working as it is so why mess with it?

[Farmaken]

But he is already making 30 RwHp so why would he need more cc`s ??

[Kickaha]

The Bucket formula seems to be working as it is so why mess with it?
Because rather than build a bike to the current rules people would like to buy/build a bike and get rules changed to suit

[TZ350]

The Bucket formula seems to be working as it is so why mess with it?

Absolutely .....

[husaberg]

Because then ESE will ask for 135cc and the coal burners will want 165cc. Where will it end???
The Bucket formula seems to be working as it is so why mess with it?

Must be just me but I cant see why people seem to be trying to fix a class that isn't broken
The point you are missing is the 4 strokes have already been given 27.5cc already. they can already use os pistons.
Why is it every time someone says give the F4's a few cc to allow the use of Kt100s pistions it turns into a debate about 80 and 85cc MX engines. gee.... stick to the subject would ya or i will pas a motion:2thumbsup

[Grumph]

The point you are missing is the 4 strokes have already been given 27.5cc already. they can ude os pistons
Why is it every time someone says give the F4's a few cc to allow the use of Kt100s pistions it turns into a debate about 80 and 85cc MX engines. gee.... stick to the subject would ya or i will pas a motion:2thumbsup

One point I will make is that an oversize MB/H 100 with the legal 24mm inlet restrictor is very competitive anyway....

No one is stopping anyone from using oversize pistons but then some tuning nous is required to get good reliable power with the inlet restriction.....tough shit, you can't buy experience.

Again, put up a remit - talking here does nothing.

[jasonu]

Yeah I thought that too. Maybe pre 1990 (or so) up to 85mxr's with stock carbs??? Certainly imposing a HP limit would be totally impractable to enforce.
Is it really necessary to change the eligability rules of a class that is already very well subscribed? The only change that has been mentioned in the last page or 2 of this thread that I think is worth considering is allowing a couple of cc's more to the watercooled 100's purely to allow more accessable piston/rings and that is only if it is true that the MB, RG400, TF100 etc pistons are no longer available.


The point you are missing is the 4 strokes have already been given 27.5cc already. they can ude os pistons
Why is it every time someone says give the F4's a few cc to allow the use of Kt100s pistions it turns into a debate about 80 and 85cc MX engines. gee.... stick to the subject would ya or i will pas a motion:2thumbsup

See above in red.
Mate put in the remit and see what happens.

[husaberg]

See above in red.
Mate put in the remit and see what happens.

Sorry i did see it and thought it was speedpro you must type alike.
I was of course responding to the why change it in the quote i quoted.....
i looked at the MNZ site and i will do it but the MNZ isn't interested in F4 and F5 anyway.



Again, put up a remit - talking here does nothing.

Neither does the MNZ

[jasonu]

One point I will make is that an oversize MB/H 100 with the legal 24mm inlet restrictor is very competitive anyway....

No one is stopping anyone from using oversize pistons but then some tuning nous is required to get good reliable power with the inlet restriction.....tough shit, you can't buy experience.

Again, put up a remit - talking here does nothing.

There is no carb restriction for the 100cc 2 strokes, you might be thinking of the 125cc aircooled 2 stroke
24mm carb limit. (or did I miss read your post...)

[wax]

Please let me know the offical rule on the engines.
125 aircooled
100cc water cooled
they are not allowed to be from a competition bike.
Do I have it close ??

[crazy man]

Please let me know the offical rule on the engines.
125 aircooled
100cc water cooled
they are not allowed to be from a competition bike.
Do I have it close ??125 aircooled 24 mm carb and 150cc four stroke
and 100cc four stroke super charged or turbo

[wax]

125 aircooled 24 mm carb and 150cc four stroke
and 100cc four stroke super charged or turbo

ok 100cc water cooled no carb restriction
And no competition engines. But road bike engines ok
Single cylinder or are you allowed twins

[jasonu]

ok 100cc water cooled no carb restriction
And no competition engines. But road bike engines ok
Single cylinder or are you allowed twins


It is all in here somewhere.
http://www.mnz.co.nz/regulations/rules/general-rules

[TZ350]

http://www.kiwibiker.co.nz/forums/images/smilies/oops.gif Page 670 already, and I have not collated the links for 660 yet .... Ok got 660 done, now working on 670's

Recently I have been trying to find the posts that talk about pipes and collate and edit them. There is heaps of it and pages 620 630 640 650 and 660 have un edited collections of raw material. If your interested in expansion chambers they are worth a look. Pages 610 600 590 580 570 ..... 100 etc all have links lists to other stuff, then there is the Thread-Tools View-Thread-Images option that also helps to find the interesting pictures and posts.




25* down angle giving the best flow. This also reduces the duct area by the cosine of the exit angle, thus reducing the duct volume.

And this then also allows steps and transitions in the flange to promote the flow exiting the Aux Ex ports, helping blowdown efficiency. The main handbrake at the limits of power production.

The flow exiting into the duct, just as the piston cracks open the port, is dropping over a cliff - the piston face. This is why the down angle helps flow, it is " pointing " the exiting gases toward the duct centre, not keeping it attached, normal to the piston dome.

P450

Squish configuration is now set in stone, be it race gas or ULP.
As long as you have the tuning aids to overcome the natural effects.
50% SAR, combined with a vertical height that allows the piston to clip in the overev is the baseline.
This gives a VERY close optimum setup, be it domed or flat top piston, combined with a toroid chamber.

The domes like a bathtub ( confirmed by Frits ) and Yamaha factory bikes.
A flat top likes a re - entrant dropped plug shape, confirmed by HRC and me, many times.
Wide, close squish will always give great acceleration, but will restrict overev if you havnt got a digital ignition to pull out timing, and a solenoid powerjet to turn off the fuel past peak torque.
Without the tuning aids you have to juggle com,static timing and squish height, to get back the overev, if its needed for the application.


The solenoid Powerjet does lean off the BSFC curve BUT, what you need to get is that all it is doing is returning the fuelling to much closer to optimum. Its not really "leaning it out "as such,it is dumping more of the available heat energy in the fuel - into the pipe, speeding up the wave action and thus extending overev available.

You know when you get there, as I did with KT100 pipe design project I did years ago.
As soon as the pipe produces more than 18Hp at the crank, the cylinder and head cannot get rid of the heat produced, and it will fade badly after 3 laps - hitting the thermal limit wall. Needing fuel to cool it, not make power. Thus I worked for months locked in a dyno room in Flat Bush extending the band width, at the expense of peak power.

P461

ATAC as short a connecting tube as you can get, diameter about 1/2 the header, ATAC vol about the same as the cylinder swept vol. We had about 1/3 of the throttle plate hanging down in the header when it was open, in line with the flow direction.

By experiment you find the point where the resonating volume starts to kill power, and then go back a couple of hundred rpm, and snap it shut with a rpm driven solenoid. Easy with the Ignitech programmable output. There is NO advantage to ramping the closing point ie interconnecting it with the PowerValve is nowhere near as effective as a single point solenoid action.

You could get even better useable band width by having a double volume system, where another plate valve opened and shut the entrance to a second bottle vol. The two being open initially, then the second vol being shut off, creating a much smaller vol that was then shut of at a higher rpm.

But hey the simple thing works a treat on engines with no option for a PV.


forum: http://www.pit-lane.biz/t117p246-gp125-caracteristiques-aprilia-rsa .
-------------------------------------------------------------------------------
Gordon Jennings certainly did a lot of good with his easy-to-read articles. But he created one misconception that is festering until this day, with his translation of the SAE-papers of Yamaha's Naitoh and Nomura into 'tuner's english'.
He extracted specific time*areas and claimed them to be the optimum values for a two-stroke. On the scavenging side he was as right as makes no difference, but on the exhaust side it was quite another story.
Naitoh and Nomura just stated their findings; Jennings concluded that specific exhaust time*area should be what Yamaha had been using. But Yamaha had by no means found a gasdynamic optimum; they just had gone as far as the quality of their piston rings allowed them to do. And had they thought of using auxiliary exhaust ducts (first seen in their present form in the 1971 Jamathi engine), they would have made a quantum leap.
Another point of criticism is that Jennings emphasised exhaust time*area and almost neglected blowdown time*area.
----------------------------------------------------------------


Nowadays an engine needs a large crankcase volume (the Aprilia RSA125's is 675 cc at TDC), all the port area you can cram into the cylinder circumference, good ducts for efficient flow and directional control, an exhaust that sucks and blows hard at the appropriate moments, and cooling, cooling, cooling.

p468

Re Blowdown STA numbers and the effect they have.
Firstly get out of your head completely the lawn mower engines view of the world that the piston dropping increases the pressure in the case, and it is this that forces the flow thru the transfers.
Mr Villiers creations may have operated this way - not any modern 2T.

When the transfers open, there is more pressure above the piston than there is case pressure in the transfer duct. This gives rise to the alarming notion that when using staggered ports, the one to open first has so much backflow that it takes ages to recover, thus it has inflow last.

The area available in the Ex from the time the port cracks, down to where the transfers open, sets the amount of combustion pressure that is lost down the duct, and thus the amount of positive pressure ratio across the open transfers ( and for how long this lasts ). We can have NO FLOW until that positive pressure ratio is reduced to the point where we have more case pressure than cylinder pressure.

There are two ways to do this - lift the case pressure and or lower the cylinder pressure. In a modern engine the case pressure is only rising very slowly due to the piston dropping, but what we do have is the pipe diffuser action, that started with the high pressure front ripping out the opening Ex port - then entering the expanding pipes front section.

As the piston approaches BDC the Ex port is starting to suck the chrome off the proverbial tow ball, dropping the cylinder pressure ratio dramatically, and it is this that forces the bulk flow into the cylinder.

If the blowdown is set correctly for the power needed within the rpm band we want, then the recovery time from the unavoidable transfer back flow at the opening point, is such that we get the correct amount of inflow to be trapped above the piston, thus creating the conditions for the correct amount of combustion pressure after the spark event.

It is this set of conditions - all revolving around the blowdown pressure, that ultimately creates how much combustion psi is developed - this creates torque, and it is this combined with rpm that creates POWER.

P472

The less clever a pipe design is, its much harder to pin down what the designers intent was, and the less it will be "port specific ".

But with say the 125 Bucket pipe, it was designed right from the get go to run with a 78* Ex port, and will only work correctly with the proper area step at the flange etc. As it has a two stage header and all manner of trickery to try and maintain the spread as well as create good peak numbers.

But there are all sorts of generalities that work, like 200* with 950 will peak at around 10500 with anything from a TZ350 to a Banshee Cheetah.

The RS125 with 196 and 830 will peak around 12000,then the A Kit with 200 and 800 will peak around 12500 but rev hard to 14,000.

But one thing that is a real fly in the ointment is the ignition - the peak prm point and the overev capability of a port timing/pipe length combination is hugely influenced by the timing and how much of the available heat energy in the fuel is dumped into the pipe, or the head/piston/water.

Best example is the Italian 125 ICC engines with fixed timing around 14*, these need a pipe some 40mm shorter than the A kit Honda to get revs near 14,000 with identical Ex timing.
The Honda has a digital ignition with a ton of retard and a solenoid powerjet, the ICC has none of this so needs a completely different approach - no free lunch.


Something to think about while the rest of the family occupy themselves with buying, boiling, painting, hiding, searching, finding and eating Easter eggs: a couple of recent videos from the Dutch 50 cc scene.
http://www.youtube.com/watch?v=mvV4xbFKs0g&feature=relmfu
http://youtu.be/0odVzSgufjk

p474

My experiences with these size exports are the following:

1. Never exceed 41mm for your bore (56mm)
2. Use at least 10mm radius for top corners
3. Use 100mm top edge radius
4. use 12mm radius for bottom corners
5. Use 80mm radius for bottom edge

Exceeding these gave more power but lead to the following:
1. Unexplained seizures
2. Broken rings after cooling off at the end of a race - runs fine and wins race, refuses to restart
3. Pinched rings - from severe hammering of piston top edge
4. Broken ring land at export
5. Ring breaks at low speed - not sure why but I think it just have more time to bulge into the export

If the only way to be competitive is to run such a port:
1. Piston and ring life is max 50km
2. Bore must be perfect
3. Very good (rounded) chamfer of top and bottom edge

I really like reading your ESE thread - gives me good feedback about where to improve my software and it is great to see such an enthusiastic bunch.

Regards
Neels



More news from Richard Maas. Did his trombone pipe give the desired results? O yes. At 10,000 rpm it gives 4 HP more than the same engine with a fixed pipe. It runs over 17,000 rpm without the need for a powerjet and with a fixed ignition timing. It is miles better than an engine with an exhaust power valve. And the mapping of pipe length, ignition timing and powerjet pulse width has yet to be carried out. Maybe the powerjet can disappear altogether.
Only problem so far: the piece of pipe that is fixed to the cylinder, is shrouded by the pipe that slides over it, so it gets very hot. Too hot for the Viton O-ring that is taking care of sealing. Any bright ideas, anyone?

P476

Running egt and cht you can watch both rise in unison as the rpm and power rise. As soon as deto starts the cht will shoot up, the egt will flat line or drop as radicals are formed in combustion. The best data logging gauge ( and the ONLY reliable egt probes ) are here.
http://www.exhaustgas.com/ProductDetail.asp?ProductID=805&DepartmentID=12&CategoryID=54&MenuID=sub4&BasketID=&RepID=


Get one of these with the extra wire to ground. When it sees deto it can ground an Ignitech input and retard the timing automatically. You get flashing lights and engine protection all in one shot, and cheap as chips - made in Czech so it likes being connected to an Ignitech - same lingo.. Works perfectly - when you get it trimmed correctly it will tell you where to manually pull out timing, then it just operates as a failsafe.

http://www.ebay.com/itm/Knock-gauge-for-detonation-sensor-klopfsensor-NEW-/110818862446?pt=Race_Car_Parts&hash=item19cd51a56e&vxp=mtr#ht_1582wt_1297


A 74% port width should not cause any ring problems. If it does, it will be because of radii being too small. With good quality piston rings you can get away with 80% port width. But that will not do your power any good; such a width requires huge port radii that will take away much blowdown area at the top corners of the port as the picture below shows.
70% width is optimal in this respect. And like Neels says, pay attention to the bottom of the port window. Rings have more time to bulge into the port when the piston is on the way down. And you can apply large bottom radii because that will not take away any blowdown area.

p480

After looking at the trombone pipe I was wondering how the very long variable header fitted in with the requirements of keeping the header and diffuser within certain % limits of the pipes tuned length but combined with the slippery it might be possible.


There are several options in lengthening a pipe. You can move the end cone, like on the above drawing, or you can lengthen the header, like on the trombone pipe.
The gas pressure generates a force that is proportional to the cross section area of the moving part and proportional to the pressure difference at either side of that area. For a moving end cone this force can be up to 4 times larger than for a sliding header. That is one reason to go for the trombone system rather than the moving cone system.

The second reason: say you wish to lengthen the total length of the pipe by 10 %. If you do it by moving the end cone, you will also enlarge the pipe volume by a little over 10 %.
But in a good pipe configuration the header length is about 1/3 of total pipe length, so in the trombone system, lengthening the pipe by 10 % will result in lengthening the header by about 30 %. That gives a far greater variation in the pipe's Helmholtz frequency than a 10 % volume change.

It is true that the length percentages of all pipe components should be in a rather fixed relation to each other. Varying the lengths of all components by the same percentage would be the theoretical optimum, but that is not feasible.
Lengthening the belly will disturb the optimum relations, as will lengthening the header. So the pipe in its lengthened version will not be the optimum for the low resonance rpm dictated by the length. But it will be a hell of a lot better than using an exhaust power valve that spoils the 180° effective exhaust timing, necessary for true resonance.
And a pipe shortened beyond its optimum may not show the optimum length relations between its components either, but it will be a lot more effective in overrev than artificially raising the exhaust gas temperature by retarding the ignition, or by weakening the mixture strenght through closing a power jet, which has the disadvantage that not all inhaled air is used for combustion.


That Dutch trombone pipe moved from +70 mm length to -20 mm length, so its effect was concentrated on the lower revs (although raising max.rpm from 14,500 to over 17,000 rpm was a welcome bonus).


Do I understand this correctly, given sufficient blow down and exhaust STA an exhaust duration of 180 deg would be the optimum at any rpm?


The short answer is yes.

When the exhaust port opens, a pressure pulse starts moving through the exhaust pipe. It is reflected at the end cone and it should be back at the cylinder just before the exhaust port closes.
Next a part of this reflected pulse bounces off the partly-closed exhaust port and a residual pulse starts moving down the exhaust pipe.

This residual pulse too is reflected by the end cone and starts moving back to the cylinder. Ideally it will arrive at the exhaust port just when the port opens again. Then the cylinder pressure and the pressure of the residual pulse combine their energy and the resulting pulse will be stronger than the pulse from the previous cycle. And the combined pulse from the next cycle will be stronger still, and so on; we have achieved true resonance.

Some may argue that we want a low pressure in the exhaust pipe when the port opens because then the spent gases will experience less resistance while leaving the cylinder. But that is not true. Gas flow depends on a pressure difference ratio. But once that ratio reaches 2, the flow velocity will reach Mach 1, the speed of sound. Raising the pressure difference any further will not raise the flow velocity any further.

The cylinder pressure at exhaust opening can be as high as 7 bar and the pressure of the reflected pulse will be about 2 bar. Thus the pressure ratio is well above 2, so lowering the pressure in the exhaust duct outside the cylinder will not do any good to the flow.

What has the exhaust timing got to do with the 'true resonance' I mentioned above?
The initial pulse starts moving at Exhaust Opening and it has to be back at Exhaust Closing, or a little earlier. This pulse travels with the speed of sound and its journey up and down the exhaust pipe will take t seconds.

The residual pulse starts moving at Exhaust Closing and it has to be back at the next Exhaust Opening. This pulse also travels with the speed of sound and its journey up and down the exhaust pipe will also take t seconds.

So from EO to EC takes t seconds and from EC to EO also takes t seconds. In English: the exhaust port should be open just as long as it should be closed.
Assuming that the crankshaft rotates with a uniform speed, this means that the crank angle during which the exhaust is open must be equal to the crank angle during which the port is closed. So both angles must be 180°.

I developed this line of thought some 40 years ago, but when I first published it in 1978 (in the motorcycle magazine Moto73 of which I was the technical editor) everybody called me crazy. Some people still do, but I got used to it .

Above I made a couple of assumptions. The crankshaft does not rotate with a uniform speed, but at high revs the deviation is negligible. In case you really want to know, I did the math for the Aprilia RSA125. At a nominal rpm of 13,000 the minimum rotation speed is 12970 rpm @ 107° after TDC and the maximum value is 13031 rpm @ 356° aTDC. What's more significant: the deviation in crankshaft position from truly uniform rotation is always less than 1°. So that really is negligible.

Second assumption: both the initial pulse and the residual pulse move with the speed of sound. Not true: the pulse pressures in exhaust waves are so high that acoustics rules do not apply any more. We are dealing with gas dynamics here and the stronger a pulse, the faster it moves. Since the residual pulse is weaker than the initial pulse, they move at different speeds. But we will leave this aside for now.

Third assumption: the initial pulse starts moving as soon as the exhaust port starts opening. More or less true, but we are not interested in the first weak appearance of the pulse; we want to know when the pulse reaches its maximum amplitude. And that requires a certain amount of open exhaust port area. It turns out that for our desired theoretical exhaust timing of 180° we will need a geometrical exhaust timing of about 190°, depending on the shape of the port: does it open gradually or does it open over its full width all at once.

The obvious question will be: why has the Aprilia RSA125 a geometrical exhaust timing of about 200°? True, at 190° the maximum torque value would be higher, but the engine would not want to rev because the blowdown time.area would be too small.
The 200° are a compromise: a bit less torque and a bit more revs; as long as the torque decline is smaller than the rpm rise, we gain horsepower.

Up to p481

[Farmaken]

Merry Christmas TZ, thanks for sharing your wins and not quite wins on your way to developing your bike. See you next year ,cheers , Ken

[Frits Overmars]

100 cc watercooled, 125 cc aircooled, 150 cc fourstroke, 100cc fourstroke supercharged or turbo. But no competition engines.Now that is a laugh. Even I could extract 40 HP from a blown 100 cc fourstroke. And a really dedicated foulstroketuner could make it 50. "But no competition engines" :facepalm:.

[husaberg]

Now that is a laugh. I will not demean myself to such activities, but even I could extract 40 HP from a blown 100 cc fourstroke. And a really dedicated foulstroketuner could make it 50.
"But no competition engines" :facepalm:.



Mr Frits have a look here.
http://www.kiwibiker.co.nz/forums/showthread.php/151469-Forced-induction-100cc
http://www.kiwibiker.co.nz/forums/showthread.php/151225-100cc-forced-induction-F4-bucket-Anyone-keen-to-have-a-real-go

[Bert]

Merry Christmas Rob and the ESE Team (and National and International contributors),
thanks for sharing all your evperiences and wisdoms, for all of us to think about and attempt to apply.

Please long may it continue.
Have a great day
Brent (and I'm sure; the rest of the GPR team).

[TZ350]

Merry Christmas TZ, thanks for sharing your wins and not quite wins


Merry Christmas Rob and the ESE Team (and National and International contributors), thanks for sharing all your evperiences and wisdoms, for all of us to think about and attempt to apply. Brent (and I'm sure; the rest of the GPR team).

Thanks guys, I very much like the positive people I meet here on KiwiBiker and at the Bucket race meetings.

May everyone have a Great Xmas doing the things they enjoy.

[2T Institute]

I have a KX80 engine in the shed and an RS125 chasis. Now lets see, the MX80 and 85 already have a bigger carb than I am currently allowed, they are water cooled, six speed close ratio and have well developed inlet, transfer and exhaust ports plus blowdown STA to spare so no need to modify the ports, all thats required is a little freshen up, and thats easily done by the shop, so all good there. And in keeping with the lazy spirit of not doing any of it ourselves we could pay someone like Wob to make the pipe. So with a little dosh and no nouse the possibilities are 30+rwhp with little effort.

The 85's are difficult to extract serious HP out of, have seen many 'claimed' 30HP at the wheel engines only to see them read 25-26HP(pretty peaky to) on a real dyno.

[FastFred]

Hi 2T I think TeeZee is all for outfits that people have built themselves and was trying to pull the punters leg. " with a little dosh and no nouse the possibilities are 30+rwhp with little effort." Speedpro is better at the sardonic windup.

Buckets is about building something yourself, there is the Hyosung Cup for those that need a stock class to ride in.

[TZ350]

275141

I have been cleaning up inside the exhaust duct and un shrouding the side ex ports.

275139

No matter how careful I tried to be tidying things up, the main Ex port which was at 73% crept out to 75%

275142


There is a dark area over the Ex port, this implies the engine has crap scavenging and has alot of short circuiting. The A transfer rearward radial angle may be too steep, allowing direct looping into the EX when at BDC

275140

Std A port angles were probably ok for a std pipe but with all the extra suck from the increased blow down and better pipe, the front of the A ports may need to be angled back some more. I will have to have a look at Frits Aprilia dwgs and some performance cylinders to see what angles they use.

[koba]

I've finally caught up with this thread again!
I feel compelled to share something at least slightly interesting and constructive.

I've been playing with TZ's old copy of MOTA over the last year and a bit.

It's been very interesting simulating engines and seeing how changes affect the end result.
The program is relatively simple and there seems to be a lot about an engines attributes that it doesn't take into account when compared to Engmod (and likely others) but it has nevertheless been helpful in gleaning a basic idea of how the fundamental engine attributes interact.

Bearing in mind I'm a compete novice and most of this is not backed up by real testing...
Some general trends I've noticed in the sim:



Reeds seem finicky, getting them right is quite hard but rewarding.

It seems very hard to have too much reed area (I suspect the down sides aren't being shown by the sim.

I have started simulating mine with a 28mm carb (It has a 28mm Mikuni flatslide from an RG150), I haven't been able to find more 'Simpower' with a 32.
(I have a 32 in the drawer but the real engine seems happier with the 28 as they are now)

Generally Speaking; more exhaust port area means more power.

I'm mindful that the pipe designs that the sim likes might be too 'sucky' for the transfers on my engine; I'm going to try a mild pipe and a wild pipe.

Better combustion efficiency is a really, really good thing to chase! (I've run most of mine at a base of 0.8 for doing comparisons between pipes and other changes.

Pipes. I can see how a factory team would try many pipe designs to squeeze out a better result!

Ignition, I must make a basic map of the 'curve' on the KX125 ignition I'm running.
It would be great to be able to change it but I'm going to have to work within that box for a while.

My engine is a port reed, MOTA doesn't really take this into consideration so I created a piston port model too with an eye towards working out the optimum timing, that was interesting as it gave similar power to the full reed sim when I got it refined, this worries me that I may still have the reed stuff wrong, I need to spend some time with the engine apart to look at this in more detail.

[TZ350]

Koba it looks like your doing quite well using MOTA for simulating the outcome of design changes. :niceone:

[koba]

So here is some of the lines I've been making:

Blue Line: This was the Dyno curve of the bike in September, roughly; the first peak was slightly higher than the second. Standard Exhaust port, modified inlet and 28mm carb.

Red Line: This is the engine parameters as they are now with the attributes like combustion and scavenging efficiency and short circuit ratio adjusted to match close to what was seen on the dyno. I had to turn these down to the lower end of the scale which suggests my engine is handicapped in some or all of these areas.
This is what I've been racing with since Te Puke.
The difference between this and the blue line was raising the barrel 1.2mm, no leak from head and widening and Raising the exhaust port. Plus I cleaned up the inlet tract which was incomplete but there is still work to do on this.

Green Line: Plan A. This is the bike with the current (Still short) port timing and a conservative pipe. My pipe design needs more work.

Pink Line: Plan B. Port timing where it should be and a steeper pipe.

Both of these 'plans' don't fully take into consideration ignition timing curves and leaning off with a powerjet so hopefully I should see more range if I get that sorted.
The Ignition "curve I used was vary basic so once I map my ignitions changes I will see If in can refine them to that better in the sim.

One other thing I have noticed, which is why I haven't bothered changing the air/fuel curve is that the sim seems to have a distorted response to this, it's easy to make 40hp in the sim by cranking the A/F ratio up so I just picked an reasonable number and used that across the board.

<img src="http://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=275159&d=1356575947/>

[F5 Dave]

Very awkwardly, not the sort of thing you want to do heading into a downhill hairpin.

Wonder where Ziff is nowadays? Obviously moved from Marton, had to seen him at Boxing day races, but not for, erm well over 10 years I guess.

Well talk about coiencidence! Last time I saw Ziffle was at the boxing day races as I said above. So who should step out of the crowd yesterday & shoulder tap me? Was n the same place as 10 years ago too. He live in Wangas, still doing plane stuff if anyone is interested

[wobbly]

Any sim you are using to design any part of a 2T engine, and dont take full account of the ignition timing regime - is a waste of time.
I can design a completely shit pipe, and with ignition tricks, make it work 1/2 way reasonable - in a sim and on the dyno.
But its impossible to design a really good pipe that will work well in reality, if you dont define exactly the ignition curve it will see when running.
You can change the temp in the header as seen by the egt probe, from 450 to 650C by simply taking away 4 degrees of timing when in the overev,so the pipe that before had a vertical power drop off
at 13500, now holds 50 + Hp out to 14500.
Same with having the solenoid powerjet scenario,you can easily make a pipe that will spin to 14,000 in the sim, but sadly it has no mid power to speak of at all.
Change the A/F ratio from 12:1 to 14:1 past torque peak, and a MUCH longer pipe, now has a ton of mid, then holds its torque up long enough for that " too long " TL to work at least another 1000 rpm than before,due to
the burning mixture now dumping a huge heat load out the port.

[koba]

Any sim you are using to design any part of a 2T engine, and dont take full account of the ignition timing regime - is a waste of time.
I can design a completely shit pipe, and with ignition tricks, make it work 1/2 way reasonable - in a sim and on the dyno.
But its impossible to design a really good pipe that will work well in reality, if you dont define exactly the ignition curve it will see when running.
You can change the temp in the header as seen by the egt probe, from 450 to 650C by simply taking away 4 degrees of timing when in the overev,so the pipe that before had a vertical power drop off
at 13500, now holds 50 + Hp out to 14500.
Same with having the solenoid powerjet scenario,you can easily make a pipe that will spin to 14,000 in the sim, but sadly it has no mid power to speak of at all.
Change the A/F ratio from 12:1 to 14:1 past torque peak, and a MUCH longer pipe, now has a ton of mid, then holds its torque up long enough for that " too long " TL to work at least another 1000 rpm than before,due to
the burning mixture now dumping a huge heat load out the port.

Cheers, I'd thought that would be the case based on what you have posted before.

It seems a little backwards designing the pipe to suit an ignition with a fixed curve shape but I'm going to have to go that way until I can afford to upgrade to an Ignitech or similar. That's going to have to wait for a long time though.
It would be great to able to change it but I have to make some compromises due to available resources.

Do you find the A/F ratio change in engmod close to reality? or do you just apply experience in that area?

Also I WILL be designing a completely shit pipe, relatively speaking, I just hope to get it less shit with the sim.

Using the Sim I've been able to compare different designs and I'm confident I can make more 'Simpower' than other pipes that I could be putting on the bike.
I would have thought the RG400 (I think it is anyway...) pipe I have on it now would be reasonably close but it appears miles off in practice and in the sim.

That is one thing about the 100 vs an Air Cooled 125; a random pipe of any old 125 seems to work OK compared to putting the same pipe on a 100.

[FastFred]

Ignition, I must make a basic map of the 'curve' on the KX125 ignition I'm running.
It would be great to be able to change it but I'm going to have to work within that box for a while.

275173

KX80/125 Fixed ignition

275172

KX80/125 Retarding igntion

This one can be converted to fixed by using a JayCar CDI blackbox replacement Kit.


Thats interesting Burt, if one had the stator part of a MX ignition they could follow the schematic and make the CDI part.

275176

It would be worth looking at the Jacar CDI kit's

[koba]

275173

KX80/125 Fixed ignition

275172

KX80/125 Retarding igntion

This one can be converted to fixed by using a JayCar CDI blackbox replacement Kit.

Mine is the retard.

Actually possibly that exact one in the picture if Kel owned it at some point.

I'm going to try and map it with a rev counter and timing light.
I know it's unlikely to be perfect but I've gotta work with what I've got.
I'm dreading working out the timing marks, I have a few ideas but know it's going to be an arse!

[FastFred]

I'm dreading working out the timing marks, I have a few ideas but know it's going to be an arse!

It might not be that hard. There will be a line on the fly wheel that aligns with a mark on the stator. These are meant to line up at 2-3k rpm.

just set the piston at its BTDC firing point, 1.6mm BTDC ??? or whatever your engine is supposed to have. Then holding the flywheel on the stator with the marks lined up, align the flywheel key way with the crank key to see if the stator and pickup coil will sit somewhere convenient.

To check the timing when you have everything bolted up. Set the piston at its firing point before TDC and using a black marker pen make a line on the flywheel and stator plate and with the timing light check these line up when the motor is running about 3-4k.

You should also see some of the retard happening but most (cheap) timing lights give up when the reves get up a bit (its to do with the time it takes to recharge the capacitor that fires the flash).

[husaberg]

To check the timing when you have everything bolted up. Set the piston at its firing point before TDC and using a black marker pen make a line on the flywheel and stator plate and with the timing light check these line up when the motor is running about 3-4k.

The misses nail polish may show up better and gives the opportunity to use different colours.(for different timings) i doubt weather it will be accurate enough to pick up much. other than trends (in the timing rather than fashion).........

[koba]

It might not be that hard. There will be a line on the fly wheel that aligns with a mark on the stator. These are meant to line up at 2-3k rpm.

just set the piston at its BTDC firing point, 1.6mm BTDC ??? or whatever your engine is supposed to have. Then holding the flywheel on the stator with the marks lined up, align the flywheel key way with the crank key to see if the stator and pickup coil will sit somewhere convenient.

To check the timing when you have everything bolted up. Set the piston at its firing point before TDC and using a black marker pen make a line on the flywheel and stator plate and with the timing light check these line up when the motor is running about 3-4k.

You should also see some of the retard happening but most (cheap) timing lights give up when the reves get up a bit (its to do with the time it takes to recharge the capacitor that fires the flash).

Umm, not quite that simple.

It's a bit of a mis-match about the place, as it is the keyways don't line up so if/when I take the flywheel off I have to re-jig every measurement!

I'm going to (one day) re-rivet the centre of the flywheel in a different position so the two key-ways line up and them machine a key down do it will fit the 4mm slot in the crank and the 3mm slot in the flywheel. To do this correctly I must first be sure of where I want it because there is very limited room in the cases to move the external pickup backwards and forwards.

So far I've been using a relative measurement for timing, from the seating surface of the plug washer to the top-centre of the piston because it's easy to measure on the spot. 23mm is standard form memory.

It's relatively simple to extrapolate the actual linear position of the piston from this but to do it properly I'd like to make a fixture to use a dial guage on it.

I've got a good, but not great, timing light; it going to shit at higher revs could be a flaw in my plans!

[koba]

Right, I've had a few beers so it took a while to appreciate that last one properly.
Yeah I know what you mean, I can get the ignition lined up correctly as per standard KX125 but what I really want to know is the curve and absolute values. To work that out I need to figure out the position relative to a measured datum, something that isn't too hard but makes my head spin.
Added to that is the dubious accuracy of the timing light.
Still, Won't know until I try!

[husaberg]

Right, I've had a few beers so it took a while to appreciate that last one properly.
Yeah I know what you mean, I can get the ignition lined up correctly as per standard KX125 but what I really want to know is the curve and absolute values. To work that out I need to figure out the position relative to a measured datum, something that isn't too hard but makes my head spin.
Added to that is the dubious accuracy of the timing light.
Still, Won't know until I try!

You could always try a MB50 ignition they to have build in retard and pit straight on and the keys and timing marks suit?
I had the standard figures i posted somewhere.i could save some head spininng.

[TZ350]

275187


There is a dark area over the Ex port, this implies the engine has crap scavenging and has alot of short circuiting, or the stinger is too small. The A transfer rearward radial angle may be too steep, allowing direct looping into the EX when at BDC

275185275186

I had a look at a few performance and race water cooled cylinders laying about the place and they all seemed to have a more swept back angle than the GP.

Interestingly the angle on the water cooled performance and race cylinders seems to point more to the rear of the cylinder as the port approaches BDC. Its like the front of the A port is contoured.


- the stinger size is a little harder to optimise, being a very high specific output air cooled and very little anecdotal evidence to point you in the right direction.

As best as I can measure it, the RS pipe I am using has a little 22.5mm restriction in the end of the baffle cone and the stinger is 23.8mm ID.

[2T Institute]

Cheers, I'd thought that would be the case based on what you have posted before.

It seems a little backwards designing the pipe to suit an ignition with a fixed curve shape but I'm going to have to go that way until I can afford to upgrade to an Ignitech or similar. That's going to have to wait for a long time though.
It would be great to able to change it but I have to make some compromises due to available resources.



You will spend more time and money friggin round with the old unknown ignition just over a longer period than biting the bullet for a programmable.
I went through this with suspension, spent countless hours rebuilding shocks, buying shims and seal heads. Finaly bought a set, bolted them on set the rebound and have not touched them since. They work 100 times better than my best efforts.

MOTA is a massive compromise especialy on the ignition side. However it will provide some useful info on the return wave timing which is what you should concentrate on. As Wob has said probably 100 times and it's worth repeating "big depression/lowest pressure at BDC" and return wave arriving before the exhaust port closes. Get that right then look to get the rpm peak where you want it, finaly jiggle the TL length %'s to what Wob has already posted. Viola no more shit pipe.

[2T Institute]

TeeZed those transfer dividers apper to be the wrong way around, they are pointing AT the exhaust port.

[Buckets4Me]

Robert junior wants to know whats gone wrong with his crf250?

275198275199275200275201

any clues as to why it locked up in top gear on him?

[cotswold]

Thanks to Rob and Culley I have made a start on porting the cases. It's amazing how much metal is removed.

The first picture is the disc valve cover

2nd The standard cases and what I'm aiming for

3rd half way there

4th Nearly finished just need to glue up the back of the left hand case to be able to put the rear port in

5th is what happens when you get carried away

The last is the left overs

[cotswold]

Robert junior wants to know whats gone wrong with his crf250?

275198275199275200275201

any clues as to why it locked up in top gear on him?

Too many parts?

[wobbly]

Actually Lozza is right - here is tomorrows job.
Fully expalins the dark area over the exhaust - a heap is short circuiting.

[TZ350]

TeeZed those transfer dividers apper to be the wrong way around, they are pointing AT the exhaust port.

275211
Good spotting, yes they do, now that's weird ..... :weird:I better have another look.

[TZ350]

275214

The rear faces forward, I think this is right but I think it could benefit from having a hook in it.

275213

I had tried to have the front of the B ports aiming straight across the barrel but they are more forward than I thought.

[TZ350]

Thanks Wob


Actually Lozza is right - here is tomorrows job.
Fully expalins the dark area over the exhaust - a heap is short circuiting.

275215

Ok so the front of the A's need to sweep back some more.

275216

Wob I intended to have the front of the Bs directly inline with each other across the bore, is that a good idea.

[husaberg]

254336CRECY ..... sleeve valve 2-Stroke, one of the most powerfull internal combustion engines ever made.

A quick Google (and display "Images") brings up some interesting info.


Really? How many ponies are in there? 3000? This will teach you to be more careful with your remarks, TeeZee :first:


Arrrr words and the games we play with them ... :laugh: ... Glad I said "one of the most powerfull", actually its a bit of a tiddler compaired to yours. I wanted to say aero engine but that would have given the game away. Maybe I should have just said "big grunty engine compaired to a Morris Minor".

254373254370 development was heading towards 5,000 bhp


There are various numbers bandied about, but this from Wiki.

The progress of jet engine development overtook that of the Crecy and replaced the need for this engine. As a result the project was cancelled in December 1945 at which point only six complete examples had been built, however an additional eight V-twins were built during the project. Crecy s/n 10 achieved 1,798 horsepower (1,341 kW) on 21 December 1944 which after adjustment for the inclusion of an exhaust turbine would have equated to 2,500 horsepower (1,900 kW).[11] (http://en.wikipedia.org/wiki/Rolls-Royce_Crecy#cite_note-10) Subsequent single-cylinder tests[12] (http://en.wikipedia.org/wiki/Rolls-Royce_Crecy#cite_note-11) achieved the equivalent of 5,000 brake horsepower (3,700 kW) for the complete engine. By June 1945 a total of 1,060 hours had been run on the V12 engines with a further 8,600 hours of testing on the V-twins.[13] (http://en.wikipedia.org/wiki/Rolls-Royce_Crecy#cite_note-12) The fate of the six Crecy engines remains unknown.


Here a bit of history on disk valve engines, yes there is a 2 stroke cosworth in there , near the bottom, the Junkers torpedo engine is pretty interesting too

http://www.douglas-self.com/MUSEUM/POWER/unusualICeng/RotaryValveIC/RotaryValveIC.htm

ok i was reading a old book today and came upon reference to a project in the late 70's or early 80's it was the Excalubur project it was secribed as one of the most ambitious projects since ww2 to produce a racing motorcyle engine that was Cross head design piston with a Sub-head primary compression and sleeve piston arrangement in a totally balanced configuration.
the 125cc versions target was 50HP at around 22000rpm.
i had a bit of a google search and the only half way acceptable references to Excalibur i find are to the rossi like powerboat..
but with the sub head i find these anyone know about the project i guess Frits may..............
i guess it is the mix of the Creasy and the ones below?
http://www.steamcar.net/images/uniflow-2.jpghttp://www.steamcar.net/movies/uniflow-engine.gif
http://www.marinediesels.info/Basics/2_stroke_crosshead_labeled.gifhttp://www.marinediesels.info/animations/loop_scavenged_animation.gif<img src="http://www.marinediesels.info/animations/uniflow_scavenge_animation.gif" height="340px"/><img src="http://www.marinediesels.info/animations/marine_diesels_small.gif" height="340px"/>

http://www.marinediesels.info/Basics/uniflow_and_loop_scavenging.htm

[wobbly]

Yep, the front wall of the B port should be perp to the bore CL.
The rear should hook and intersect 1/2 way between bore centre and the boost face, with a big rad in the corner right to the bore.

[TZ350]

Thanks Wob

I went back through the thread pictures and found this one.

275222

[TZ350]

I wanted to fit another piston that has the ring gap in a better place.

275224

FarmerKen put me onto this 86 YZ125 piston with a dome. I had been using the flat top piston because that made it easy to form the squish with a flat copper plate. But I guess now is the time to change.

275228

The dome is good in lots of ways, one of them means that I can have a head shape like Frits and Wob suggest for leaded fuel.

275225

Because of the dome I have to take 2.5cc out of the head, so its easy for me to get that flat dome head shape.

275226

The purists mighten approve but this is the quick and dirty way of measuring the crown angle using the cross slides angle adjustment. And disapproving purists certainly don't want to know how I cced the head as I opend the chamber up but in the end it worked out real well.

275227

A big thanks to Gigglebutton for letting me use his lathe.

275223

If I need to go there later, there is enough material left to carve a toroid head and lower the compression a bit more for unleaded.

[husaberg]

Thanks Wob

I went back through the thread pictures and found this one.

275222
http://img140.imageshack.us/img140/4103/apriliacylinderpistonsk.jpg
not sure if this was the rotax or aprilia
http://img651.imageshack.us/img651/697/apriliaducts.jpg

[TZ350]

Thanks Husa ...

[husaberg]

I thought I'd ask the smart people here a question if I may. I've been planning to build a dyno and have been working on design and finding materials. Yesterday I happened across this:
<img src="http://i48.photobucket.com/albums/f224/cookie1965/dyno-1.jpg" width="240px"/>
It's an old Heenan Froude water brake. Funny, it's been sitting in my machinists shop the whole time we were talking inertia dyno design ideas and he never mentioned it until yesterday when we were at another shop having one of his race car motors dyno'd lol.
I was wondering if, say money were no object LOL, would I be better off converting this with a modern load cell, sensors and software or should I stick to my original plan of an inertia dyno. Or maybe there's a third option I haven't thought of?
TIA

My first brake (we're talking 1978) was a Heenan & Froude, same as yours, only a larger version.
The main problem was that its torque absorbtion curve was less steep than the torque curve of a racing two-stroke. So either the engine rpm would be stuck at a point somewhere in the torque dip, or it would shoot right past max. torque rpm, past max. power rpm and even past max. mechanical safe rpm.
A partial solution was to triple the water pressure in the whole system, but stabilizing engine rpm via the brake's handwheel remained a hell of a job.
My advice: stick to your original plan of an inertia dyno.

Dead right Frits.
All the water brake dynos I have seen that worked well with high output 2Ts needed additional inertia,to enable the operator,or the software
to adjust the valving quick enough to get anything like a consistent load .
Even the best well adjusted PID loop control goes bananas trying to hang onto the rate of change a good 2T produces.
i am the messenger remember..............
i can't say i totally agree with the article but it is interesting i will post Berts air paddle dyno photo later.

Notice in the picture Bill Lacey responable for the last single cylinder win in the senior Manx 1961 against the MV4's no less (ok so they broke) (Hailwood plain bearing big end and Jag rod) holder of many records pre ww2 war as a rider/tuner (he preferred to be called engineer)on his own bikes.he also worked on GP car engines.

[Yow Ling]

Seeing as F4 is way too fast , F5 is dominated by the 50cc zealots from Wellington, if i have any chance of ever winning a title I will need to create my own class F6

49cc single speed pre 1960 that should narrow the field a bit

Heres my entry, after reading in depth about small frontal area , light weight skinny tyres I have arrived at this formula

275248 275249 275250 275251

maybe some of the senior bucket guys like speedpro can shed some of their wisdom as he can probably remember them when they were new

[TZ350]

I love it ... :laugh:

[TZ350]

It's relatively simple to extrapolate the actual linear position of the piston from this but to do it properly I'd like to make a fixture to use a dial guage on it.

As I remember it, for a fixed ignition on the Team ESE Suzuki GP125's .....

1.5 to 2.3mm BTDC

1.5 or 16deg for squish head and 2 to 2.3mm giving 22-26deg for an open chamber head.

Beware .... timing lights take a fixed but finite amount of time to flash after the spark event and as the rpm goes up this delay makes the ignition look like it is retarding. How much??? well that depends on your particular timing light.

This false http://www.kiwibiker.co.nz/forums/images/smilies/blank.gif retarding as the rev's go up, is just something else to look out for.

[dinamik2t]

TZ, that pic was created from the drawings provided by Frits (the old APC cylinder)!

Here's a more complete one: (there is a small mismatch)
275254
It includes the exhaust ducts.
But we already know from the APF 3d drawings, that the aux EX ducts' rear wall angles needn't have to be so steep. :)

[Frits Overmars]

Seeing as F4 is way too fast , F5 is dominated by the 50cc zealots from Wellington, if i have any chance of ever winning a title I will need to create my own class F6 49cc single speed pre 1960 that should narrow the field a bit.
Heres my entry, after reading in depth about small frontal area , light weight skinny tyres I have arrived at this formula

275248 275249 275250 275251

maybe some of the senior bucket guys like speedpro can shed some of their wisdom as he can probably remember them when they were newI'm afraid your mass distribution is less than optimal; you might want to have more load on the front wheel.
Ever considered Solex racing ? (yes, it's another crazy Dutch thing. But the French picked up on it as well :weird:).

[TZ350]

I have made a start on porting the cases. It's amazing how much metal is removed.

They are looking good Cots .....

[TZ350]

275265

Ok this is what Wob suggested I should try for.

And after a whole lot of work ...... a small improvement but to do any better I need a small right angle drive so I can reach inside the cylinder.

275268 275267

A ports ...

The front of the A port sweeps back a little more than the std cylinder did and the rear wall of the A port has been moved a little more towards the center. On the std cylinder the rear wall of the A port pointed back towards the center of the boost port.

275269 275266

B ports ...

The front of the B port faces straight across the cylinder and the rear sweeps around and meets its opposit about half way between the rear wall and the center of the cylinder.

[Yow Ling]

I'm afraid your mass distribution is less than optimal; you might want to have more load on the front wheel.
Ever considered Solex racing ? (yes, it's another crazy Dutch thing. But the French picked up on it as well :weird:).


Hi Frits, they look a bit chalenging to race, I have a Solex in the shed and also a Batavus Go Go, didnt realise the Solex was Dutch, might start loving it a little more now !. I thought the Solex was an accidentt waiting to happen, seems once you have the knack they have hidden potential.

[Frits Overmars]

I didnt realise the Solex was Dutch, might start loving it a little more now !It originated in France, but there was a Solex factory in Holland as well, so we started doing crazy things with it.
I thought the Solex was an accident waiting to happen.You bet: a flimsy frame, no wheelbase to speak of, and ditto brakes. But racing a two-wheeler with front wheel drive is something special. The Solex that we prepared about 20 years ago left black tire marks accelerating out of corners. It didn't do too bad at the Solexracing world championship either.... :first:

[jasonu]

Seeing as F4 is way too fast , F5 is dominated by the 50cc zealots from Wellington, if i have any chance of ever winning a title I will need to create my own class F6

49cc single speed pre 1960 that should narrow the field a bit

Heres my entry, after reading in depth about small frontal area , light weight skinny tyres I have arrived at this formula

275248 275249 275250 275251

maybe some of the senior bucket guys like speedpro can shed some of their wisdom as he can probably remember them when they were new

Only if it is a non competition engine<_<

[twotempi]

49cc single speed pre 1960 that should narrow the field a bit

A new pre 63 class for the Classic Register ??????:yes::yes::yes:

[F5 Dave]

Seeing as F4 is way too fast , F5 is dominated by the 50cc zealots from Wellington, . . .

Zealot!?!

Oh you are a charmer Mike:love:

[koba]

You could always try a MB50 ignition they to have build in retard and pit straight on and the keys and timing marks suit?
I had the standard figures i posted somewhere.i could save some head spininng.

Yet to find one for sale. Haven't looked that hard but over a long period. I can go to fixed as suggested too. I really do need to build a pipe soon, shit or not it will be better as kilos lighter and will allow me the room I need to jack up the rear end.

[F5 Dave]

WTF, they were consummate shitee. Used to run one on the H100, it was crap.

[koba]

You will spend more time and money friggin round with the old unknown ignition just over a longer period than biting the bullet for a programmable.
I went through this with suspension, spent countless hours rebuilding shocks, buying shims and seal heads. Finaly bought a set, bolted them on set the rebound and have not touched them since. They work 100 times better than my best efforts.


Haha, yeah I know the feeling!
I absolutely agree, except for the money part. Having said that the time penalty will be massive.

Still, I'm in it for the fun and I enjoy the workshop side too so I don't mind too much.
Money bled over a longer period is always easier to reconcile.

At this point it's going to cost me nothing but time to build a pipe that won't be as good as it could be but I can rectify that at a later point.
I know I can make my bike faster on track by building a new pipe that allows the rear end to be raised.
I'm currently riding a 14hp bike (20 is fast becoming average) with around 25deg rake on Kart tracks.




MOTA is a massive compromise especialy on the ignition side. However it will provide some useful info on the return wave timing which is what you should concentrate on. As Wob has said probably 100 times and it's worth repeating "big depression/lowest pressure at BDC" and return wave arriving before the exhaust port closes. Get that right then look to get the rpm peak where you want it, finaly jiggle the TL length %'s to what Wob has already posted. Viola no more shit pipe.


Cheers, I'm still getting my head around it all but will keep that burned in my brain next time I have a good MOTA session.
Also must balance that against how hard I can suck on my transfers without them losing control, yeah?

(Gosh that sounds awful!)

[koba]

WTF, they were consummate shitee. Used to run one on the H100, it was crap.

I was looking at anything that would be an upgrade to standard, bolt on aspect appealed. KX one seems to be OK, will run it for now until I go all out and buy something with a lightweight rotor and the ability to run an ignitech.

[2T Institute]

275265

Ok this is what Wob suggested I should try for.

And after a whole lot of work ...... a small improvement but to do any better I need a small right angle drive so I can reach inside the cylinder.

275268 275267

A ports ...

The front of the A port sweeps back a little more than the std cylinder did and the rear wall of the A port has been moved a little more towards the center. On the std cylinder the rear wall of the A port pointed back towards the center of the boost port.

275269 275266

B ports ...

The front of the B port faces straight across the cylinder and the rear sweeps around and meets its opposit about half way between the rear wall and the center of the cylinder.

time to delete those dividers and start again, I don't think any amount of JB Weld is going to fix those ducts.

[husaberg]

Yet to find one for sale. Haven't looked that hard but over a long period. I can go to fixed as suggested too. I really do need to build a pipe soon, shit or not it will be better as kilos lighter and will allow me the room I need to jack up the rear end.


WTF, they were consummate shitee. Used to run one on the H100, it was crap.

Hillie has a few, i would say by now including my old cr80 AC one minus the cdi unit.

Dave they have a high-speed retard built in, They bolt on. they have a known curve they line up wit the timing plate (the std MB100 actually advances.) From memory the MB50 curve starts at around 19 degrees and comes back to 15 at 9000rpm odd. Yes possibly not the best match, but from memory Kobas motor is fairly tame.
cheapest fix i can think of for a fully static is the c90 cdi supposedly unit most Diesel cdi's they can handle quite a few revs, and it would work with almost any cdi stator.
I seem to recall Mike posting that his motor likes it basically fixed till around 13000rpm
conversely in a budget the CR80 had a nice tidy stator set up and i would go for that first go.
I do remember there was a tiny unit supplied as an accessory for chainsaws that used to be used on a lot of kt100's and similar engines a well.
People have often spoken of adding delay boxes to standard cdi units even with trim pots to alter the standard curves.
i have posted a company before that used to do them. Plus an article on it.

But of course the ultimate answer is the ignitech or similar.
would a oscilloscopes be able to map the ignition timing if a hall effect trigger was added to display tdc
I seen this today which i guess is a similar set up to Wobs ignition tester in a way.

http://www.youtube.com/watch?v=NwjcIbRwen8


Koba i possibly might have a cdi and could have a stator flywheel you can have (free) but i would have to look at the oldmans.
But at the end of the day why would you want Cause Dave says it's shitee.

PS Koba i don't see any advantage to a lighter rotor didn't stop me doing it but no advantage i could tell other than it when we over-lightened the first one it fell to bits.

[Frits Overmars]

Standing in the line of fire of such a degree wheel spinning at 10,000 rpm is a great way of catching an arterial bleeding....

[ief]

I was bored so... not exactly like lozza says but perhaps in the right direction (pun intended)

Nothing a bit of jbweld can't fix is it? :banana:

[TZ350]

Thanks guys for the porting overlays.

275325

Here is something I found amongst Frits's Aprilia stuff. Its a cross section across the transfer port windows.

275328

This is what the standard Suzuki GP125 looks like.

275327

This is how I open up the rear transfer B Ports.

275326

The Suzuki GP has this strange Siamese port arrangement inside.

275329

There is only so much I can do with these tools, I would love to get a small right angle hand piece that fits inside the cylinder.

275330

Because the GP's ducts twist around, the angle that a duct window points across the cylinder is different to the angle you can see at the duct entry. I can't seem to make good photos of their true shape.

[husaberg]

Standing in the line of fire of such a degree wheel spinning at 10,000 rpm is a great way of catching an arterial bleeding....

You better not watch this one of his other videos then:shit:
This one is worse!!!! i think he even realises this, as he starts shaking the camera.
(Even Bert ran his chain with a guard)
i heave heard of these style dyno's bit never seen one.
I think Grumph said a HQ disk is good for 100hp

http://www.youtube.com/watch?v=EZakJkqW-hc&list=UUnfxmHz5jOKG5n0JN1nFTBQ&index=37

[koba]

Hillie has a few, i would say by now including my old cr80 AC one minus the cdi unit.

Dave they have a high-speed retard built in, They bolt on. they have a known curve they line up wit the timing plate (the std MB100 actually advances.) From memory the MB50 curve starts at around 19 degrees and comes back to 15 at 9000rpm odd. Yes possibly not the best match, but from memory Kobas motor is fairly tame.
cheapest fix i can think of for a fully static is the c90 cdi supposedly unit most Diesel cdi's they can handle quite a few revs, and it would work with almost any cdi stator.
I seem to recall Mike posting that his motor likes it basically fixed till around 13000rpm
conversely in a budget the CR80 had a nice tidy stator set up and i would go for that first go.
I do remember there was a tiny unit supplied as an accessory for chainsaws that used to be used on a lot of kt100's and similar engines a well.
People have often spoken of adding delay boxes to standard cdi units even with trim pots to alter the standard curves.
i have posted a company before that used to do them. Plus an article on it.

But of course the ultimate answer is the ignitech or similar.
would a oscilloscopes be able to map the ignition timing if a hall effect trigger was added to display tdc
I seen this today which i guess is a similar set up to Wobs ignition tester in a way.


Koba i possibly might have a cdi and could have a stator flywheel you can have (free) but i would have to look at the oldmans.
But at the end of the day why would you want Cause Dave says it's shitee.

PS Koba i don't see any advantage to a lighter rotor didn't stop me doing it but no advantage i could tell other than it when we over-lightened the first one it fell to bits.

Dave nagged me for ages saying I need to get a lighter rotor on it, the difference was huge and noticeable immediately.
It was heaps better in many ways, including off the line.

Cheers, no worries about the ignition; I'm going to work with what I've got for a while.
The ignition is OK for my needs right now, there are other changes that will lower lap-times quicker.

[wobbly]

TeeZee - Air flow in a duct hates being bent in 3D.
Transfer ports all have to "go around the corner " into the cylinder, so having the duct twisted along its length just to achieve the correct radial angle of entry, is dramatically reducing flow.
That is why I coloured the septum divider in red, on the Paint picture of the duct entries.
Fill the duct walls, to A, reduce the total volume, and B, to get the front and rear walls at the correct angle, axially, along the duct length correct right from the start.

[TZ350]

TeeZee - Air flow in a duct hates being bent in 3D.

Fill the duct walls, to A, reduce the total volume, and B, to get the front and rear walls at the correct angle, axially, along the duct length correct right from the start.

:pinch: more work .......

OK after Taumarunui which is next weekend, I will make a complete new cylinder as this one is getting a bit tatty.

[husaberg]

Dave nagged me for ages saying I need to get a lighter rotor on it, the difference was huge and noticeable immediately.
It was heaps better in many ways, including off the line.


Not exactly an apples for apple comparison though....... is it or is it?
I are guessing you are comparing a totally different ignition system rather than just a lighter rotor.

I guess Frits and Wob might be able to explain why high flywheel inertia can be a advantage....
i think Wob mentioned previously about what happens when the RS125 rotor mass is lowered.
Plus why the RSA( i think it was the RSA) is full of very heavy metal...Mallory???? Tungsten????? depleted Uranium?????
i seem to remember something from physics about the having the weight concentrated at the periphery you can have the same interia with less overall weight or something like that (are sure will be corrected):wacko:
i guess it will accelerate faster from different revs i guess faster with less flywheel inetia

Like i said i could find no obvious advantage from a lower mass flywheel (lap times)with the same ignition (other than at a standstill)
maybe is was my shitee MB50 ignition:pinch:

but a lighter set of wheels that i would notice

[Ocean1]

i seem to remember something from physics about the having the weight concentrated at the periphery you can have the same interia with less overall weight or something like that (are sure will be corrected):wacko:
i guess it will accelerate faster from different revs i guess faster with less flywheel inetia

Yep. Any mass you have to spool up cost you acceleration, and unless you've invested in kinetic energy recovery tech you don't get it back. F1 engines have no flywheel at all, they have enough mass in the crank that it's inertia alone keeps them ticking over at the minimum revs they're required to run at.

[FastFred]

http://www.youtube.com/watch?v=NwjcIbRwen8




http://www.youtube.com/watch?v=EZakJkqW-hc&list=UUnfxmHz5jOKG5n0JN1nFTBQ&index=37

Just love his philosophy ......

[F5 Dave]

. . .
i guess it will accelerate faster from different revs i guess faster with less flywheel inetia

Like i said i could find no obvious advantage from a lower mass flywheel (lap times)with the same ignition (other than at a standstill)
maybe is was my shitee MB50 ignition:pinch:

ahh c'mon think about it. An MB was a 70s road bike that needed to cope with learner riders & city traffic. It had a dirty great flywheel to aid clutch starts. It is way too big for a race bike. Wob has enlightened us that too light will affect the ability to rev to extremes. I always figured there was sweet spot of mass, but never the result of too light.

The CR80 ign was an imediate improvement on the H100 (just as it had been on the MB50) over the left over MB50 one I had replaced the H's points ign. The reduced mass didn't affect starts, in fact the opposite, there was still heaps.

Further, swapping to the CR ign stopped the irratating habit of burning through a spark plug every one & 1/2 meetings as it did with the MB ign, probably a decent compression ratio over the roadbike was a step too far.

As I said, it was Shite. Dunno why I waste my time.

[TZ350]

275334

True to form, when I opened the stable door some of the ponies escaped.

Red line is what we had when we did the back to back with Rich's bike before Tokoroa.

Blue is what I have now after a weeks work improving things ...... :crazy:

It is amazing, after a little tickle up in the ports the carburation is so rich down low it barely runs and then takes of from about 8-9k like a cut cat then signs of early.

[Farmaken]

How much of the change in output can you attribute to the ports/ducts and how much to the head shape/commpression ratio ??

You did say your measuring system might make people blush ! :pinch:

[husaberg]

Not exactly an apples for apple comparison though....... is it or is it?
I are guessing you are comparing a totally different ignition system rather than just a lighter rotor.

Like i said i could find no obvious advantage from a lower mass flywheel (lap times)with the same ignition (other than at a standstill)
maybe is was my shitee MB50 ignition:pinch:

but a lighter set of wheels that i would notice


ahh c'mon think about it. An MB was a 70s road bike that needed to cope with learner riders & city traffic. It had a dirty great flywheel to aid clutch starts. It is way too big for a race bike. Wob has enlightened us that too light will affect the ability to rev to extremes. I always figured there was sweet spot of mass, but never the result of too light.

The CR80 ign was an imediate improvement on the H100 (just as it had been on the MB50) over the left over MB50 one I had replaced the H's points ign. The reduced mass didn't affect starts, in fact the opposite, there was still heaps.

Further, swapping to the CR ign stopped the irratating habit of burning through a spark plug every one & 1/2 meetings as it did with the MB ign, probably a decent compression ratio over the roadbike was a step too far.

As I said, it was Shite. Dunno why I waste my time.

i dunno why you reply before reading the entire post.........apple vs apples vs oranges vs kiwifruit


Early RS125s had an external rotor the same as the CR125 it was derived from.
The later GP only RS125 engine had an internal rotor about the same as the RSW/RSA with a much higher inertia crank assy.
When changing to total loss and removing the small rotor, the engine had no overev at all.
So much higher inertia cranks were made by VHM and the factory for this application.
The RSW/RSA crank inertia is very high due to full circle and plated wheels and added Mallory, to be able to run with the small rotor assy.
It matters not where the inertia comes from - the wheels or the rotor create overev by reducing the in cycle speed variations of the crank assy, at the expense of outright acceleration capability.

[teriks]

Standing in the line of fire of such a degree wheel spinning at 10,000 rpm is a great way of catching an arterial bleeding....
My thoughts too, and that comes from someone used to dealing with cf-props at 30+ krpm. That made me nervous!

[TZ350]

How much of the change in output can you attribute to the ports/ducts and how much to the head shape/commpression ratio ??

I dropped the compression a touch for reliability but I am not sure about the head shape, copying something of Frits's seemed like a good idea at the time.

The port duct changes should have helped reduce short circuiting as the main thrust of the changes were to direct the transfer stream away from the exhaust port at BDC and followed a layout that worked for me before.

I think the problem is with the cleaned up exhaust port and un shroudeding of the side exhaust ports. Same actual timing but I think there is now more effective blowdown time area and the engine is looking for a pipe more suited to peaking at 13-14K rpm than the 12 of the RS pipe I have been using.

It is something I have seen in the EngMod2T simulations too, same ex port timing but increased blowdown from wider or side ex ports and the power curve wants to move up the rev scale.

When I can I will dust Wobblys Parana pipe off and give it another go.

I may have over cooked it on this cylinder with its 203 deg duration exhaust. But if I am right about the effect of the extra blowdown time area from the side ports then that suggests. I could make another one with 190 duration for a broad power spread and enough effective blow down time area from the hand carved side ports for good hp at lower revs. But it wont be happening this week.

[TZ350]

275343

Ok The blue line is where the 3 Ex port cylinder and RS pipe are at now. I dont think the RS pipe suits the new cylinder because the RS pipe wants to peak at only 12K.

275345

The STA's for the 3 Ex port cylinder showing high 30's at the rear wheel is possible for someone who can cut metal into shapes that faithfully replicates the design.

275344

EngMod2T simulation with 83% combustion efficency and Wobs pipe shows that the power will peak around 14K for the 3 Ex cylinder.

There is a nice flat area to the torque curve in the 12.5 to 14.5K area and if I can get a CVT setup to work in that range we could have a rocket ship.

I havnt got my head around everything about CVT's yet but from what I have read and heard from Wax and Frits the amount of rev drop when the throttle is backed off can be controlled by changing the angle and or shape of the slots in the rear pulley sheave.

Speedpro suggested to me that I could fit a sleeve thats been cut with my own slot arrangement to a std pully. Now I could make a pulley sheave with slots curved in such a way that the rpm drop varies depending on the CVT's current ratio or how fast its going. Slow speed low gear (1st 2nd 3rd gear in old gear box talk) the rpm drops more and at high speed high gear high load (4th 5th gear) the rpm is held nearly constant around peak power.

[FastFred]

275343

Ok The blue line is where the 3 Ex port cylinder and RS pipe are at now. I dont think the RS pipe suits the new cylinder

So you didn't get such a great result today but it looks like there is still plenty of promise.

Outright hp has not been all conquering so there has to be a new way of doing it, a fundamental change.

I am looking forward to seeing how the CVT thing develops. :corn:

[koba]

i dunno why you reply before reading the entire post.........apple vs apples vs oranges vs kiwifruit

My take on this is:

If 0 was the optimum ammount of inertia for my bike then a standard rotor may be say, 100.

The KX one could be, perhaps, 20.

To little inertia could be had by grinding down the crank wheels or whatever to get a similar ratio to a competition engine, then with the no ignition rotor and just a plate for an ignition pickup perhaps it would be say, -100.

Yes, putting the new ignition on changed at least 3 aspects: rotating mass, nature of the spark and the timing curve BUT knowing the bike well, I can say, with enough certainty to convince my own sceptical mind; the reduction in mass was positive in every aspect.

I can really fell it when coasting with the clutch in and matching engine revs to road speed before releasing the leaver.
(like when one fucks up a shift)

[koba]

275343

Ok The blue line is where the 3 Ex port cylinder and RS pipe are at now.

I'd tap that.

[koba]

...grinding down the crank wheels or whatever...

...and replacing the area with a lighter substitute of the same volume, so as to not affect the primary compression ratio or any airflow characteristics in the crank case... ;)

[Frits Overmars]

...and replacing the area with a lighter substitute of the same volume, so as to not affect the primary compression ratio or any airflow characteristics in the crank case...Might I suggest a mixture of air and petrol ? :msn-wink:
By all means do enlarge the crankcase volume.

[husaberg]

Might I suggest a mixture of air and petrol ? :msn-wink:
By all means do enlarge the crankcase volume.

Frits can you clarify something for me. I was attempting to read a forum translated from Dutch the other day.
The post was from Jan. I think it said something along the lines that you were able to obtain an extra .5 hp on( i think the RSA) by either extending the coolant channel either direcly into the transfer septum.or furter into it? Was this a foible of google translate?
because .5 HP is a very dramatic increase for such a highly developed engine?. That certainly would have been beers all around i guess.
http://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=241576&stc=1&thumb=1&d=1298323382

[Frits Overmars]

Jan was talking about coolant passages inside the inner curvatures of the transfer ducts. I have no pictures of those (cutting RSA cylinders in half would be a bit of a costly hobby) but here is a picture of my FOS cylinder with the same coolant ducts.

[Grumph]

Jan was talking about coolant passages inside the inner curvatures of the transfer ducts. I have no pictures of those (cutting RSA cylinders in half would be a bit of a costly hobby) but here is a picture of my FOS cylinder with the same coolant ducts.

That's a tricky bit of patternmaking - which I would not like to try.....

[koba]

I guess that would get more and more important with such high performance engines having the hot ducts and the cold ducts so close over so much area...

[Yow Ling]

That's a tricky bit of patternmaking - which I would not like to try.....

isnt that the same as the cheese in the pizza crust, cant be that hard !

[husaberg]

Jan was talking about coolant passages inside the inner curvatures of the transfer ducts. I have no pictures of those (cutting RSA cylinders in half would be a bit of a costly hobby) but here is a picture of my FOS cylinder with the same coolant ducts.

Dank u wel.
Are you familiar with rapid milk cooling systems.
I guess it would still be easier to do the water galleries on the 2 stroke than the oil galleries in a RC166.
In your cylinder are these formed with a cast in small diameter pipe insert?

[2T Institute]

Yep. Any mass you have to spool up cost you acceleration, and unless you've invested in kinetic energy recovery tech you don't get it back. F1 engines have no flywheel at all, they have enough mass in the crank that it's inertia alone keeps them ticking over at the minimum revs they're required to run at.

Reality doesn't agree, flywheel weights gain a lot of traction and drivability (ask any CR500 owner), with a lot of inertia you don't drop a lot rpm when the throttle is closed under brakes. Getting on the throttle earlier does wonders for acceleration.

[Ocean1]

Reality doesn't agree, flywheel weights gain a lot of traction and drivability (ask any CR500 owner),

Yes, I was pouring lead into 2T trials bike flywheels... a long time ago, for exactly that reason. But I guess these guys aren't really pushing the limits of traction under simple acceleration.


with a lot of inertia you don't drop a lot rpm when the throttle is closed under brakes.

Which can be a bit of a problem if you're desperately trying to scrub speed going into turn 1. Unless you keep the clutch in, in which case I suppose it's a valid energy storage strategy.


Getting on the throttle earlier does wonders for acceleration.

Absolutely, a bit of time on a BSA bushman is good for refining one's antici

[Bert]

Back to the CVT concept, I found this interesting.

You will need to translate it.

http://www.2t-special.it/forum/viewtopic.php?f=14&t=3819

[Frits Overmars]

Are you familiar with rapid milk cooling systems?No, I'm not. Is it something we could use?

I guess it would still be easier to do the water galleries on the 2 stroke than the oil galleries in a RC166. In your cylinder are these formed with a cast in small diameter pipe insert?My cylinders are not cast at all; they are produced with Selective Laser Melting
(Institute for Complex Materials, Leibnitz Institute for Solid State and Materials Research Dresden, Germany, www.ifw-dresden.de (http://www.ifw-dresden.de) ).

[koba]

Hey TZ, what fuel do you run?

[koba]

Back to the CVT concept, I found this interesting.

You will need to translate it.

http://www.2t-special.it/forum/viewtopic.php?f=14&t=3819

Just looking at the pics tells a good story!

[Ocean1]

My cylinders are not cast at all; they are produced with Selective Laser Melting
(Institute for Complex Materials, Leibnitz Institute for Solid State and Materials Research Dresden, Germany, www.ifw-dresden.de (http://www.ifw-dresden.de) ).

That's a very cute trick, I wasn't aware the technology had come quite so far.
I know of a similar process, used to make a water pump, including a free-floating impeller built completely enclosed within the pump cavity. Removes design constraints I didn't really even know existed until such processes came along...

[TZ350]

Back to the CVT concept, I found this interesting.

You will need to translate it.

http://www.2t-special.it/forum/viewtopic.php?f=14&t=3819

Interesting CVT 250 and it looks like it is using the rims of the flywheels as rotary valves.

275391

[TZ350]

Hey TZ, what fuel do you run?

Av gas, supposedly for its consistency and we run 20:1 oil ratio .... but we are looking to go to pump gas but a bit of re-tuning will be required to make the switch.

[koba]

Av gas supposedly for its consistency and 20:1 oil ratio .... but we are looking to go to pump gas.

True, I was wondering about that as when looking back over the data for the 30hp single port engine I noticed the 13.9:1 Compression ratio and wondered if it was too high.

I hope to machine my head sometime soon so I've been thinking about it.

When Hels had Dave's old H100 we had to go to the Aero club and buy avgas for it which was a real pain in the dick.
We mixed this with 98 octane pump fuel.
I think I will try to get mine nice on high octane pump.

It has been nice using 91 in it so far but those days may be over soon.

As an interesting side note I've had very few vehicles that actually benefited from high octane pump fuel, my old turbo car was one and my A100 would pink on 91 at "high" speed. Interesting it would sometimes pink on BP 98 but other 'premium' fuels seemed OK.

Oh, I've been running around about 30:1 of whatever is cheapest synthetic at the time.
I'll probably have to start getting a bit more precise on all that soon...

[Neal]

Av gas, supposedly for its consistency and we run 20:1 oil ratio .... but we are looking to go to pump gas but a bit of re-tuning will be required to make the switch.

I think you will lose midrange power when you do that .

[husaberg]

No, I'm not. Is it something we could use?
My cylinders are not cast at all; they are produced with Selective Laser Melting
(Institute for Complex Materials, Leibnitz Institute for Solid State and Materials Research Dresden, Germany, www.ifw-dresden.de (http://www.ifw-dresden.de) ).

Probably not it will just be another of my crackpot ideas.:yes:
Primarily milk cooling is conducted with a plate cooler which is basically a radiator using a continuous stream of water a total loss system.( the water is recycled for dairy cleaning, sometimes through a heat exchanger to recover the heat to preheat the hot water for plant cleaning.
<img src="http://www.kristal-dd.co.uk/images/plate-cooler_wall-mounted.jpg" width="120px"/>
this only reduces the temperature from arround 36 degrees (cow temp) to about 18-20 degrees (ie only able to within a couple of degrees of the cooling water)
The temperature of the remaining milk is further cooled to 4 degrees with a refrigeration unit and cooling pad in the milk silo.

One of the alternatives is to use an ice bank, with is basically a bank of ice around a simple coil (much like worm in a still or a beer keg after cooler or an ice filled intercooler) although the ice bank constantly creates more ice with it refrigeration unit
<img src="http://www.kegking.com.au/Images/jockeybox.png" width="120px"/>
With this approach the milk is instantly cooled from 36 ish to less than 10 degrees. At a flow rate of about 1.5 liters/second(The specific heat of fusion for ice (ie how much energy per kilogram is required to melt it is 334 kJ/Kg)

From both your and Jan's posts i have seen how dramatically the temperature of the inlet charge effects the engines power.
you said previously this would require a radiator as large as the engines. It still could be worth it though couldn't it?
An additional system to cool only the crankcase and transfers with much cooler water would it seems potentially dramatically raise the output.

Of course it adds weight and complication and fails the KISS test. So like i said it would be another of my crackpot ideas..
That said camping car fridge cooling pads are light and you don't even need to use ice as some special waxes and gases have amazing cooling capacities.........
sodium has be used to move and dissipate head..Manx Norton. Or the Coworth Ford that had the onboard CO2 fire extinguisher spraying on the intercooler
<img src="http://us1.webpublications.com.au/static/images/articles/i1102/110205_6lo.jpg" width="120px"/>
80 watt Peltier.........

oh Frits before i forget On your FOS engine with the ctv how are you going to lubricate the counterbalancer bearings?


Av gas, supposedly for its consistency and we run 20:1 oil ratio .... but we are looking to go to pump gas but a bit of re-tuning will be required to make the switch.
Is it a myth that Avgas runs cooler?????????????????????????

[TZ350]

275392

Fitted the B cylinder and its all sorted for Taumarunui.

[kel]

275392

Fitted the B cylinder and its all sorted for Taumarunui.

B cylinder with the modified head and new piston? Do you have a dyno run for this cylinder with the old combustion chamber shape?
Your B cylinders torque curve would put a lot of 4 strokes to shame :yes:

[SS90]

275392

Fitted the B cylinder and its all sorted for Taumarunui.

Erm this is far better as far as power delivery goes than the previous cylinder.

If you started looking at optimising this set up (as far as pipe design goes), you will finally have a winner.
Time to bin the RS pipe I say, back to Basics on the head too

Forget about the few extra ponies, this is the right direction, 2013 could be the year that ESE a real championship contender.

[Gigglebutton]

275392

Fitted the B cylinder and its all sorted for Taumarunui.

Nice work Rob

[cotswold]

Nice work Rob

I agree looks great :woohoo: , happy new year lads...

[RMS eng]

275392

Fitted the B cylinder and its all sorted for Taumarunui.

looks alot like jasons 20 year old 25HP KE100 dyno sheet,still won't be as good as jasons new bucket RS125 frame with CBR150 motor 22HP and 78 kg we hope?

[TZ350]

... jasons new bucket RS125 frame with CBR150 motor 22HP and 78 kg

I think a 22 hp 4-stroke in a superb chassis thats 78kg all up will be very hard to beat on the track, the Beast is about 93kg.

[Yow Ling]

looks alot like jasons 20 year old 25HP KE100 dyno sheet,still won't be as good as jasons new bucket RS125 frame with CBR150 motor 22HP and 78 kg we hope?

Is it going to be a virtual bucket or one that goes to the track?

[Gigglebutton]

I agree looks great :woohoo: , happy new year lads...

Happy New Year to you Tim :)

[jasonu]

Is it going to be a virtual bucket or one that goes to the track?

Probably virtual...

[FastFred]

These are just some of the posts. TeeZee did a lot of work on the dyno trying different carburetor setups, particularly getting the balance between the main jet and air correction jet right.


258280258281258282

OK, used a bit of 1/4" SS tube and linished it down to 6mm, spinning the job with a battery drill makes for a fairly round finish, cleared the end with a center drill, tapped a 13mm length into the carb, Job done. The hole next to it is plugged and I may smooth it off with glue sometime.

But now I guess I have to go back and check it on the dyno again.

I may be able to use a bigger mainjet now more air will be going through the air correction jet.

Bigger main jet should mean richer down low to mid for smoother drive at the lower end of the torqe curve and then drill the air correction jet out untill the top makes best power.

258284

On other sessions while testing different carbs the area between 8 and 9 K on the graph, the curve was much smother and sounded better on the dyno when it was richer there.

258285

The blue line was the IE carb I tried a while back, the jetting on one of the runs didn't make much power but it drove well in the 8-9K area.

I wonder if with a bit of playing with a bigger main jet and carefully drilling out the air correction jet I can get the red line to drive as smoothly.


I can make more power (31rwhp) with a smaller mj but these two curves illustrate my point nicely. Insted of leaning it out on the mj and losing the bottom end of the torqe curve, I should look at changing the fuel curve to get the best at both ends.

258395

Red line 150mj, Blue line 120mj, now what I wan't to do is use the air correction jet to lean the 150mj off towards the top end and the emulsion tube to tailor the curve so the two curves combine.


257204257205257206

Working on the EI carb with the 24mm venturi behind the slide, its a bit of a trick getting the mixture right. Its easy to wind the needle up and down and have it either rich on top lean below or the other way around. But not having a good selection of needles, I am having to stone the flats on the two needles I have, to try and get a profile that fuels correctly.

257208257203257207

A comparison of the OKO with the 24mm restriction in the bellmouth like Frits suggested (Red Line) and the EI carb with the venturi behind the slide idea (Blue Line).

I am still working on tuning the EI carb and haven't completly given up on the venturi behind the slide idea yet but the 24mm venturi restriction in the bellmouth concept does look promising.


257152



257151257150



257146257147257148

Its a little grey, some people feel a carb should always be measured at the same point that the original manufacturer measured it, but yes the rules seem to allow carb mods and we have tried your idea before and it worked OK.

The interesting thing is, that the signal strength was much greater and we had to reduce the main jet, we went from 140 down to 100 which is the smallest we could get, made 31rwhp with the 100mj, maybe there is more if we could get smaller jets.

When I settle on a carb configuration Lectron are open to looking at providing them as 24mm specials if they like the design, then the carbs would be available on special order to anyone who wants one so they will be completely within the rules or a punter could save quite a few $$$ and modify something for themselves.

I would not be surprised to see the B cylinder or a variation of it with its long flat torque curve making closer to 30 hp soon.

[SS90]

I would not be surprised to see the B cylinder or a variation of it with its long flat torque curve making closer to 30 hp soon.

......And a little boy waits.......

[FastFred]

I currently don't post in the (ESE) thread, because I really don't want ... Frits Overmars ... to see the childishness and think Kiwis are drongos!

http://www.kiwibiker.co.nz/forums/converse.php?u=34520&u2=13818


But then again, (F5Dave) you have Never worked in the industry .... Any reason for this mind numbing advise?


I am suitably qualified to question the accuracy of websites on this subject matter.


In an effort to get some clear information written before the local fools start replying


Oh my god, Bucketracer is a child! If I had known earlier, I would have ignored him from day 1. Is he getting his first razor next Christmas?


Once again a pimply wank poof teenager gets it wrong


As usual, we have a teenager with no experience thinking he knows everything. You are, of course, as always, wrong.



Geee, You havn't been following there have you? I will write this REALLY SIMPLY.



......And a little boy waits.......

............. :corn:

[FastFred]

What is this about the air passing 3 times passed the main jet?

I honestly have never heard about that... Can you elborate a bit?

Is this only on you bike, or do all Two strokes do this?

Does the air go into the engine, taking the fuel with it, the the disc valve closes, the incoming air "bounce" off the now closed valve, return passed the main jet, picking up more fuel with it, and then enter the wrong way out the carb, into the atmosphere, then, when the disc valve opens again, the negative pressure of the engine create a depression, so the positive air behind the carb ( now some of which is charged with fuel) again pass through the bell mouth, passed the emus lion tube, picking up more fuel as it does, then in through the open disc valve and into the engine.

Is this the 3 three times charge you talk of?

This is new to me.
Am I correct in my breakdown of this?

Because this is new to me.


Well I'm confused, is this sarcasm?


Yea, poorly worded sarcasm. fuel does not pass through 3 times, it was worded that way by Teezee, and I really am trying to keep this thread going in a constructive factual way …

I guess you were wrong, but by being a drongo and trying to mock TeeZee you actually explained what really happens.

""the air goes into the engine, taking the fuel with it, the the disc valve closes, the incoming air "bounce" off the now closed valve, return passed the main jet, picking up more fuel with it, and then enter the wrong way out the carb, into the atmosphere, then, when the disc valve opens again, the negative pressure of the engine create a depression, so the positive air behind the carb ( now some of which is charged with fuel) again pass through the bell mouth, passed the emus lion tube, picking up more fuel as it does, then in through the open disc valve and into the engine.""

You mocked it, but yes, some fuel does pass three times at full power.

<iframe width="420" height="315" src="http://www.youtube.com/embed/KcNfci9OruU" frameborder="0" allowfullscreen></iframe>

If I am wrong, maybe you could explain why, ss90 here is a video clip to help you get your head around it.

But to be honest, I think you are wrong again and I am not saying I think your full of it.

But 3 times past is something that I would have expected someone from the tuning industry who claims lots of experience with dynos and this kind of engine to have known about.

[husaberg]

That's quite interesting sonic_v.

personally, I have never seen more that 21PS from an engine with a 24mm carb, regardless of bell mouth/venturi design.

Two years ago I was lucky enough to work with someone who uses MOTA for a living, and was quickly shown that it is a tool that requires years of experience.

With an experienced operator on a 125cc aircoled engine the result was always 21PS, and when we built that engine, it was pretty much 20PS.

Previously (when I had tried to use the program) I, like Teezee and Thomas has seen 28PS as a prediction.

I simply didn't have the experience.

I too had thought that 24PS or so was possible, but I don't know of anyone who has built a 125cc air cooled disc valve engine with a 24mm carb that has more than 20PS.

OK, I don't knnow everyone in the world, but the limitations of that carb size, particularly operating over 9,000 RPM is quite something to overcome.

I will see if I can find a copy of the dyno runs.

My experience with air cooled 125cc engines to get around the BMEP you are suggesting requires a carb size in the area of 28 to 30MM.

Have you found different?

I guess he has..........

[ief]

You guys love your old cows don't you?

Happy new year btw :)

edit: seems this doesn't translate to well...

'Don't drag old cows out of the ditch means approximately to let sleeping dogs lie' (dutch expression)

[Frits Overmars]

...oh Frits before i forget On your FOS engine with the ctv how are you going to lubricate the counterbalancer bearings? Oil-filled bearings (they keep very well in a number of 50 cc engines) and maybe a little prayer or two.


Is it a myth that Avgas runs cooler?????????????????????????Yo. Avgas doesn't; Avgas runs hotter. But Avgas engines may run cooler because of their higher compression / expansion ratio , hence much cooler exhaust gases.

[husaberg]

Hus - it's all very well to pull out these old articles about equating 2 vs 4 strokes, but.......

Jan Thiel 16th September 2012

A 2 stroke gives about 1.7 times the power of a 4 stroke, with equal displacement.



You guys love your old cows don't you?

OH her ,she is merely a T shirt Model. Our NZ Cows are much fatter and Voluptuous.

Oil-filled bearings (they keep very well in a number of 50 cc engines) and maybe a little prayer or two.

Yo. Avgas doesn't; Avgas runs hotter. But Avgas engines may run cooler because of their higher compression / expansion ratio , hence much cooler exhaust gases.
Re the bearings....Thanks I was playing around with a basic drawing and had a "oh that's a problem moment" re the bearings and final drive output doe a CTV.
The AV gas was a pondererance for Rob and the thread but yes it was far from clearly worded. Re his Air cooling..............

Are you able to shed any light on the "Excalibur project" engine project i posted a few pages back?

Also would you ask Jan if i could post some of his frame pictures on the chassis thread?

[Grumph]

Jan Thiel 16th September 2012


1.7 ratio.....so with unlimited 100cc 2 strokes, you're now going to push for 170cc 4 strokes ?

i think this cow can safely be left in a back paddock.....

[husaberg]

1.7 ratio.....so with unlimited 100cc 2 strokes, you're now going to push for 170cc 4 strokes ?

i think this cow can safely be left in a back paddock.....

reverse your maths..........100cc÷.70=142cc
or 112cc ÷.7=158.5cc:msn-wink:

[richban]

reverse your maths..........100cc÷.70=142cc
or 112cc ÷.7=158.5cc:msn-wink:

112cc x 1.7 =190.4cc Now thats more like it. Good idea Husa.:cool:

[timg]

112cc x 1.7 =190.4cc Now thats more like it. Good idea Husa.:cool: Yours is already there aye? :dodge:

[richban]

Yours is already there aye? :dodge:

Yeah nah. No need 24 is heaps. Goes all day two. 30 would be nice for the big jobs but there are only 2 of those in NZ. BOB and the GP. 1 is almost an hour long and the other should be 30mins so yep a 24hp reliable coal burner has quite a good chance. As has been proven time and time again. The rules are fine.

I would love to try ride the beast one day. :msn-wink:

[husaberg]

. As has been proven time and time again. The rules are fine.


buckets started as F4 104cc 2 strokes 130.5cc fours strokes
then it was 140cc four strokes
then 145cc fours strokes
then 150cc four strokes
now 158cc four strokes

yeah only changes when it suits aye..........:bleh:

[richban]

buckets started as F4 104cc 2 strokes 130.5cc fours strokes
then it was 140cc four strokes
then 145cc fours strokes
then 150cc four strokes
now 158cc four strokes

yeah only changes when it suits aye..........


You know as well as I that the 4 strokes were short changes massively in the rules till now. I am sure one day someone will make 30hp from 4 stroke. But at the moment I think it would cost to much $.

Anyway hows your bike going.:argue:

[koba]

A 20hp+ four stroke is so easy to go fast on it feels like cheating.
Maybe I should get one too...

Nah!

[richban]

A 20hp+ four stroke is so easy to go fast on it feels like cheating.
Maybe I should get one too...

Nah!


Exactly what Dave M said about riding a 30hp 2 stroke at the GP. He had to slow down to make it look like a race.

[Yow Ling]

we had a couple of fxrs on our dyno today 15 hp off the trailer 18hp back on the trailer, owner was well pleased
We still pretty clueless about the whole black art , now we have about 50 runs under our belt we starting to scratch the surface, neighbours not complaining yet.

[husaberg]

You know as well as I that the 4 strokes were short changes massively in the rules till now. I am sure one day someone will make 30hp from 4 stroke. But at the moment I think it would cost to much $.

Anyway hows your bike going.:argue:
Oh how i for for those poor 4 strokes suffering along there all impoverished under the rules:violin:
Vanessa is awaiting the engine delivery for the initial dress fitting,
but it might be taking another tangent in light of a recent discovery.........:sherlock:

[richban]

we had a couple of fxrs on our dyno today 15 hp off the trailer 18hp back on the trailer, owner was well pleased
We still pretty clueless about the whole black art , now we have about 50 runs under our belt we starting to scratch the surface, neighbours not complaining yet.

Good work. The first 5 come easy its the other 4 or 5 that cost.

[richban]

but it might be taking another tangent in light of a recent discovery.........:sherlock:

You have finally figured that if you want to win races your engine should fire half as many times.:lol:

[Yow Ling]

Good work. The first 5 come easy its the other 4 or 5 that cost.

We not gluttons, since Tims bucket went north, the fast diesels are around 20hp

[Yow Ling]

You have finally figured that if you want to win races your engine should fire half as many times.:lol:

To win a race first you have to start !
Ive started hundreds of races and only won bugger all , 5 maybe

[richban]

We not gluttons, since Tims bucket went north, the fast diesels are around 20hp

Well that's all you need for the skinny kids. Its the old boys need the ponies.

[Buddha#81]

seems one of the faster FXR's down here was running at 13.7 HP geez now he has 18.15 no wonder he left with a smile:msn-wink:

[seymour14]

Sounds like a good gain, I'd be smiling too!

Like I always say "A car is a motorcycle with trainer wheels". Go you bucketeers, go! :headbang:

[husaberg]

You have finally figured that if you want to win races your engine should fire half as many times.:lol:
No i have a diesel work ute already. For me to win races would require far more than 30hp plus a multiple pile up and some actual talent.

To win a race first you have to start !
Ive started hundreds of races and only won bugger all , 5 maybe
I can't fault your sentiment:lol:
Finger has been pulled out.:msn-wink:

[koba]

No i have a diesel work ute already. For me to win races would require far more than 30hp plus a multiple pile up and some actual talent.

I can't fault your sentiment:lol:
Finger has been pulled out.:msn-wink:

Remember not to pick your nose until after you wash it.

[cotswold]

:devil2:
You have finally figured that if you want to win races your engine should fire half as many times.:lol:

Yet to see a diesel lap the entire field at a NI round

[Pumba]

:devil2:

Yet to see a diesel lap the entire field at a NI round

Doesn't need to. You get the same points regardless of how far ahead you are:msn-wink:

Although we could change that. Water Ski Racing uses a formula that awards 1000 points to the winner of a race, and then dependant on how far behind the lead rider you are depends on what points you get e.g. 1000 points for the winner, second place is 1 sec back will get 998 odd points, the guy in 3 that has been lapped 6 times may only get 400 odd, and so on. Hope you get the idea.

[TZ350]

:devil2:

Yet to see a diesel lap the entire field at a NI round

I am picking thats a record that will stand for a while, lapping the entire field including the past and current GP champions.

The bike was prepaired by Chambers for Av. Bucketracer and Thomas helped out with the dyno work.

[speedpro]

Me and Ziffle lapped most of the field at the last Wigram GP, maybe even 3rd place.
Me and Jim lapped most of the field at a Taupo GP, and again maybe even 3rd place.
Memory is pretty poor and it seems I may have been faster than I thought, or something.

[husaberg]

Me and Ziffle lapped most of the field at the last Wigram GP, maybe even 3rd place.
Me and Jim lapped most of the field at a Taupo GP, and again maybe even 3rd place.
Memory is pretty poor and it seems I may have been faster than I thought, or something.

Someone tried to compile a list didn't they last year of the results of the last 10 years or so it wouldn't make great reading for the two strokes...................

found some old Taupo track lap times,now track 3,2002 Taupo GP no chicanes winner J steadman KE100 best lap 49.93,m green MB100 50.82,C Morgan CB125T 53.72.50cc race C Sale RG50 best lap 55.49.100cc race was 30 laps,50cc race 20 laps.J steadmans bike was a KE with RG400 cylinder with 20+ HP,have video of steve diprose on Rams old 18hp TF100 beating Jimmy at a Taupo bucket day.so lap times should come down with all these so called big HP buckets.




Al Hoogie (ex 125GP champ) won BOB by a meter from.......
James Hoogie, got second at BOB and lapped third.....Rich somebody?


For those interested in a bit of history, this feat has been achieved before.
Nigel Duff won the GP 3x in a row 2006, 2007 & 2008.
Jimmy Steadman won 3x in a row 1990, 1991 & 1992.
Jimmy also won the GP 5 other times between 1982 & 2002. First & last wins 20 years apart!
Morley Shirriffs also won 3x but not consecutively.
The most consecutive F4 wins was Paul Ramsey with 4x in a row 1986, 1987, 1988 & 1989.
Also Pete Sales won the F5 GP 7x in a row from 1984 to 1990
That's a pretty good target for Andrew!
2012 bob

Hoogie 1st,2nd,3rd. All very close to the end. Lapped everyone else. And Matthew, the youngest, 2nd on the FXR, just to show the CBR's are no better.
CONGRATULATIONS!!

2011 Winter Series
Gavin Veltmeyer 200
Richard Ford 137
Tim Coopey 101


Top 21 totals For NI Series 2010....
Tim Fraser 132
Tyler Firn 103
Rick Ford 100

http://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=264768&stc=1&thumb=1&d=1339282498


From the official results and as I remember it.(2009 Taupo)
In the two F4/F5 all in races Nathanial Diprose rode a 50 into 5th (BT 1:32:35) and 7th (BT 1:30:79) respectively, and there were at least 10 Diesels behind him. :girlfight:

The fast guys were:-

Andrew Adlam FXR150 Wellington 1st in the GP (BT 1:27:48) ? and 2nd in the two F4/F5 combined races.

Darryl Cotton Honda RS/MB100 CHCH 2nd in the GP (BT 1:27:39) 1st and 1st in the two F4/F5 combined races.

Neil Batchelor MB100 Rangiera 3rd in th GP (BT 1:27:94) 2nd and 3rd in the two F4/F5 combined races.

Other fast runners were:-

Gavin Veltmeyer FXR150 Auck 4th in the GP (BT 1:28:76) 3rd and 4th in the two F4/F5 combined races.

Richard Ford FXR150 Auck 5th in the GP (BT 1:28:88) 4th and 6th in the two F4/F5 combined races.

Tim Frazer FXR150 Auck 6th in the GP (BT 1:28:89) 6th and 5th in the two F4/F5 combined races.

And the best time recorded by a Team ESE bike was NedKelly on his RS/GP125 at 1:29:52

The worst moment was when Chambers high sided of his bike in practice, knocked himself out and was hit by another bike that could not avoid him. Chambers recovered pretty quickly and now has a big bruse on his bum, there are pictures some where.

The best moment was watching Avalon on Chambers bike start from the back of the GP grid and cut her way to near the front in one lap. On the second lap her race was cut short when she fell at the same spot as Chambers had, she re-mounted and sensibly rode a more reserved race for a finish, 12th I think.

Chambers GP100 sure had the leggs needed but getting the old GP frame to handle well enough to run at the front might be a bridge to far.

.



Results Taupo road race spectacularDate Dec 28, 2010 11:56:00 AM

1 2 Andrew Adlam
8 12:44.423 1:33.874 7 84.368
2 31 Gavin Veltmeyer
8 12:49.726 5.303 1:34.499 7 83.810
3 88 Nathanael Diprose
8 13:16.928 32.505 1:35.974 2 82.52

[koba]

EngMod can be used at any level of experience.
Only problem that occurs is crap in = crap out, and you can get VERY mislead in trying any variations of say a pipe design if you
don't know how to optimise the other variables to suit a change.
For example you can spend days getting a really good power graph of a pipe for a 125, but if you run all the sims with a 19mm stinger, the design is flawed from
the start, and will never work on a real engine, no matter how good the sim result seems.
You can, simply run the sim and read off the graphs that pipe A is "better "than pipe B.
But then you can start to "read "the pressure traces within any part of the system and begin to learn WHY a change was better or worse.
And you can graph TuMax to see what is happening in the cylinder head with the squish and timing curve you have entered.
This is the beginning of real tuning knowledge.
One thing that used to be a good help was to use TSR to get in the ballpark with initial EngMod entries, and now Neels has started to help out
with a generic pipe design calculator, but the only way to really get an understanding is to watch the problems caused by a 37% header,on the screen, in real time.

Trawling old stuff and this sums up my current position well!

Still, It's all learning and all good fun!

[Frits Overmars]

....I was playing around with a basic drawing and had a "oh that's a problem moment"Consider yourself lucky; I have a 'oh that's a problem life' with some bright moments.

Are you able to shed any light on the "Excalibur project" engine project i posted a few pages back?I was going to ask you to define 'a few pages' but I found it in the end:
... it was secribed as one of the most ambitious projects since ww2 to produce a racing motorcyle engine that was Cross head design piston with a Sub-head primary compression and sleeve piston arrangement in a totally balanced configuration. the 125cc versions target was 50HP at around 22000rpm.Yeah, right. I do not see a balanced configuration, I do not see 50 HP and I certainly don't see 22000 rpm with a cross-head. All I see is camshafts and valves ...
Also would you ask Jan if i could post some of his frame pictures on the chassis thread?I will not ask anybody to post anything on any forum, least of all Jan; it's not like he has any spare time. But feel free to send him a PM.

[husaberg]

Also would you ask Jan if i could post some of his frame pictures on the chassis thread?;)


..I will not ask anybody to post anything on any forum, least of all Jan; it's not like he has any spare time. But feel free to send him a PM.
Frits i think you way have misunderstood my question, but point taken ..............
I certainly didn't intend to offend you with the question or think you could or should influence Jan to post them.
The request to ask Jan (if it was all right as a courtesy) for me to post some of Jan chassis pictures he had shared out of another thread, May be better received from his friend rather than waste his time dealing with a total stranger such as myself. I appreciate you are of course well over qualified to be a messenger boy.

ok i was reading a old book today and came upon reference to a project in the late 70's or early 80's it was the Excalubur project it was decribed as one of the most ambitious projects since ww2 to produce a racing motorcyle engine that was Cross head design piston with a Sub-head primary compression and sleeve piston arrangement in a totally balanced configuration.
the 125cc versions target was 50HP at around 22000rpm.
i had a bit of a google search and the only half way acceptable references to Excalibur i find are to the rossi like powerboat..
but with the sub head i find these anyone know about the project i guess Frits may..............
i guess it is the mix of the Creasy and the ones below?

The Excalibur project i assume failed. (Like a lot of other English world beaters) but i can find only brief mentions of it in the press in passing.
i put together those pictures as i had not heard of a crosshead and sub primary configuration.
Do you recall the English project? Agreed it seemingly had over optimistic expectations.
I are guessing the layout would have been considerably different that what i added (i hope)
http://www.marinediesels.info/animations/loop_scavenged_animation.gif

[crazy man]

l'm prity shore Morley Shirriffs laped the hole feild at the foxton gp l was in 3th and dave d ... l could see was in sec . l got lap with around 10 laps to go on mr pogo stick so would say he got dave easy as well

[TZ350]

I have learnt a lot from MOTA and EngMod2T and like Koba, I am a great fan of simulation tools.


EngMod can be used at any level of experience. Only problem that occurs is crap in = crap out, and you can get VERY mislead in trying any variations of say a pipe design if you don't know how to optimise the other variables to suit a change.
For example you can spend days getting a really good power graph of a pipe for a 125, but if you run all the sims with a 19mm stinger, the design is flawed from the start, and will never work on a real engine, no matter how good the sim result seems.

I don't know all that much about the subtitles of pipes, so this is pretty much where I am at.


You can, simply run the sim and read off the graphs that pipe A is "better "than pipe B.

Recently I have been trying to find all the posts that talk about pipes and collate and edit them.

There is heaps of it, and on pages 620 630 640 650 660 670 I have posted un edited collections of raw material. If your interested in expansion chambers they are worth a look.

Pages 610 600 590 580 570 ..... 100 etc all have links lists to other stuff, then there is the Thread-Tools View-Thread-Images option that also helps to find the interesting pictures and posts.

275487

Xmas holiday happiness planing a new engine with EngMod2T

275488

STA's for my new engine at 12K rpm.

275489

STA's for the same engine at 9K rpm.

On the 9k data the 40hp numbers for the exhaust port, blowdown, transfers and Inlet don't mean that the motor will make 40hp they only mean that the holes are big enough for 40hp at 9K and 36 at 12k.


But then you can start to "read "the pressure traces within any part of the system and begin to learn WHY a change was better or worse.
And you can graph TuMax to see what is happening in the cylinder head with the squish and timing curve you have entered.

This is the beginning of real tuning knowledge. One thing that used to be a good help was to use TSR to get in the ballpark with initial EngMod entries, and now Neels has started to help out
with a generic pipe design calculator, but the only way to really get an understanding is to watch the problems caused by a 37% header,on the screen, in real time.

The trick is to move enough wind through the engine as possible using resonance and then one might be able to make 35 crank hp at 9k and 12K. EngMod2T is a great tool for figuring out whats possible and the best way to plan your engine development approach.

The plan is to develop a trombone pipe that peaks at 9k and as it closes up extends the power peak to 12K and 35hp.

What are you doing for fun over the Christmas Holidays .......... :D

[TZ350]

The design objective of the pipe is a power curve peaking at 9,000 rpm and that carries on flat to 12,000rpm.

275491

Ok ... we have the STA's to do the job and the basic engine details are shown below.

[wobbly]

This is the perfect time for me to step in and tell you to stop dreaming.
40Hp at 9,000 for a 125cc engine = 16Bar = 230 psi bmep.
ABSOLUTELY IMPOSSIBLE, NEVER BEEN EVEN REMOTELY APPROACHED, AND NEVER WILL BE.
New Years Wake Up Call.

[richban]

What are you doing for fun over the Christmas Holidays .......... :D


Similar stuff. I am designing and building new headers to try find that happy place. Will be interesting to see where it ends up.

[TZ350]

You beat me to it by a little bit.


40Hp at 9,000 for a 125cc engine = 16Bar = 230 psi bmep. ABSOLUTELY IMPOSSIBLE ...

Yes I understand that, but 36 crank hp at 12K is 11 bar and thats possible, I have been close to that already.

Its that the ports for 36hp at 12K are big enough for an impossible 40 at 9 and this suggests some sort of power valve arrangement on the ports could be good.

The objective is to get the highest torqe we can at 9k and finish with 36 crank hp at 12k.

Basically the torqe curve peaks at 9 and the power curve runs flat to 12 as the torque curve declines.

I have no idea of whats possible but I will find out what can be done as the design process develops.

275497

36 crank hp at 12,000 rpm requires 11 bar, Been there done that, or at least close.

275498

36 crank hp at 9,000 rpm requires 14+ bar, possible but difficult and maybe not thermaly possible for an air cooled motor.

At least I now where I have to go in chamber design, peaky Road Race at 9K.

[ief]

Shouldn't you work the other way around i.e. make optimum setup for 36 hp @ 12 k and then use the trombone to gain torque below?

Otherwise torque will fall of after 9 k, would that be driveable? (if doable at all)

[TZ350]

Shouldn't you work the other way around i.e. make optimum setup for 36 hp @ 12 k and then use the trombone to gain torque below?

Yes I thought so too, but in my EngMod2T simulations I always found it worked best to shorten the pipe and carry the power on.

Shortening the pipe also kept the vital header and diffuser length percentages within range for longer.

Lengthening the pipe did not work so well.

Thats why I want to start at 9 and carry on to 12.


Otherwise torque will fall of after 9 k, would that be driveable? (if doable at all)

Yes, the torque will fall off as the rpm goes up, thats how its possible to get a flat power curve. Will that be drivable, I think so.

I have seen flat power curves on dyno graphs, so it can be done, can I do it???? maybe.

[husaberg]

Yes I thought so too, but in my EngMod2T simulations I always found it worked best to shorten the pipe and carry the power on.

Shortening the pipe also kept the vital header and diffuser length percentages within range for longer.

Lengthening the pipe did not work so well.

Thats why I want to start at 9 and carry on to 12.

I thought, though likely wrong that the trombone shortens to gain over rev.Rather than lengthens to gain low end power???????
i certainly are no expert :weep:but it took me a while to get my head around that it may be better to first aim for the peak that you want.
(This is two strokes in general) i think it came from Wob or Frits, when i asked about trying to spread the power by tuning say inlet to a sightly different rev than say exhaust
it was said that it was better to use cunning tricks like solenoid carbs and ignition tricks and maybe a trombone pipe to spread the power by increasing the over-rev. rather than using other methods to broaden the power down low. but i am pretty sure this is a half quote probably out of context.........

[Farmaken]

I was playing with Mota just yesterday trying a very basic trombone/ATAC sim

Used a pipe that gave good top end and over-rev and added 100mm to the header length to represent the ATAC chamber or extended trombone header

Long header fattened up the bottom end/mid from 7k and fell over at about 10k - shorter pipe makes max power at 12500

If I was less of a computer retard I would post the graphs :weep:

[TZ350]

I thought, though likely wrong that the trombone shortens to gain over rev. Rather than lengthens to gain low end power???????

Yes, the Trombone that Frits showed us went both ways, but its about keeping things in resonance and we know from Frits that 190 deg exhaust duration is the target number.

(190 . 192 ex duration???? I will have to find the original post to confirm the exact number Frits said.)

But if your short on blow down STA, although its not ideal, you might have to increase the exhaust duration even though around 190 works the best at keeping the pipe in strong resonance. So exhaust duration becomes another trade off.

As I understand it .....

(1) 190 deg Ex duration is the magic number regardless of rpm.

(2) To remain in resonance the pipe shortens as rpm goes up.

So by dynamically changing the pipes length you can keep it in resonance with the exhaust port as the rpm changes.

From running a few EngMod2T simulations I have formed the idea that a Trombone style pipe gives a better result being shortened than lengthened.

I think thats because shortening the pipe also kept the vital header and diffuser length percentages within range for longer than lengthening the pipe seemed to do.

That is why I want to start at 9k and run out to 12.

[husaberg]

That Dutch trombone pipe moved from +70 mm length to -20 mm length, so its effect was concentrated on the lower revs (although raising max.rpm from 14,500 to over 17,000 rpm was a welcome bonus).

oh got that wrong more than usual.......:clap:
can't find the post either ROB but found these.........

Thanks Frits for your answer about the 180 deg port duration.

262139

Here is a simulation of the Trombone effect. Datum is at 14500 and it went -30mm and extended +45mm, for a total slide movement of 75mm. Seems to be more more of an effect at peak power than at the lower revs.

Its a very interesting idea, being able to extend the power peak like that .... now what could I do with that :scratch:

The short answer is yes. But why is it that each time you people sit down for five minutes to write a question, I have to sit down for two hours to write an answer?:msn-wink:

When the exhaust port opens, a pressure pulse starts moving through the exhaust pipe. It is reflected at the end cone and it should be back at the cylinder just before the exhaust port closes.
Next a part of this reflected pulse bounces off the partly-closed exhaust port and a residual pulse starts moving down the exhaust pipe. This residual pulse too is reflected by the end cone and starts moving back to the cylinder. Ideally it will arrive at the exhaust port just when the port opens again. Then the cylinder pressure and the pressure of the residual pulse combine their energy and the resulting pulse will be stronger than the pulse from the previous cycle. And the combined pulse from the next cycle will be stronger still, and so on; we have achieved true resonance.

Some may argue that we want a low pressure in the exhaust pipe when the port opens because then the spent gases will experience less resistance while leaving the cylinder. But that is not true. Gas flow depends on a pressure difference ratio. But once that ratio reaches 2, the flow velocity will reach Mach 1, the speed of sound. Raising the pressure difference any further will not raise the flow velocity any further.
The cylinder pressure at exhaust opening can be as high as 7 bar and the pressure of the reflected pulse will be about 2 bar. Thus the pressure ratio is well above 2, so lowering the pressure in the exhaust duct outside the cylinder will not do any good to the flow.

What has the exhaust timing got to do with the 'true resonance' I mentioned above?
The initial pulse starts moving at Exhaust Opening and it has to be back at Exhaust Closing, or a little earlier. This pulse travels with the speed of sound and its journey up and down the exhaust pipe will take t seconds.
The residual pulse starts moving at Exhaust Closing and it has to be back at the next Exhaust Opening. This pulse also travels with the speed of sound and its journey up and down the exhaust pipe will also take t seconds.
So from EO to EC takes t seconds and from EC to EO also takes t seconds. In English: the exhaust port should be open just as long as it should be closed.
Assuming that the crankshaft rotates with a uniform speed, this means that the crank angle during which the exhaust is open must be equal to the crank angle during which the port is closed. So both angles must be 180°.

I developed this line of thought some 40 years ago, but when I first published it in 1978 (in the motorcycle magazine Moto73 of which I was the technical editor) everybody called me crazy. Some people still do, but I got used to it :p.

Above I made a couple of assumptions. The crankshaft does not rotate with a uniform speed, but at high revs the deviation is negligible. In case you really want to know, I did the math for the Aprilia RSA125. At a nominal rpm of 13,000 the minimum rotation speed is 12970 rpm @ 107° after TDC and the maximum value is 13031 rpm @ 356° aTDC. What's more significant: the deviation in crankshaft position from truly uniform rotation is always less than 1°. So that really is negligible.

Second assumption: both the initial pulse and the residual pulse move with the speed of sound. Not true: the pulse pressures in exhaust waves are so high that acoustics rules do not apply any more. We are dealing with gas dynamics here and the stronger a pulse, the faster it moves. Since the residual pulse is weaker than the initial pulse, they move at different speeds. But we will leave this aside for now.

Third assumption: the initial pulse starts moving as soon as the exhaust port starts opening. More or less true, but we are not interested in the first weak appearance of the pulse; we want to know when the pulse reaches its maximum amplitude. And that requires a certain amount of open exhaust port area. It turns out that for our desired theoretical exhaust timing of 180° we will need a geometrical exhaust timing of about 190°, depending on the shape of the port: does it open gradually or does it open over its full width all at once.

The obvious question will be: why has the Aprilia RSA125 a geometrical exhaust timing of about 200°? True, at 190° the maximum torque value would be higher, but the engine would not want to rev because the blowdown time.area would be too small.
The 200° are a compromise: a bit less torque and a bit more revs; as long as the torque decline is smaller than the rpm rise, we gain horsepower.



We would get by with 6 gears like we did in the 125 cc class until Dorna killed it last year. Don't be misled by the Aprilia's power valves. They were there because the same cylinders had to be used on the 250 twins, which would have been too vicious without them. The 125s did not really need them. And having many gears to cope with is a big disadvantage. Not only does each gearshift interrupt the power, bringing unwanted movement in the bike and distracting the rider, it also interrupts the gas dynamic processes in the engine which means full power won't be available right after each shift.


Francis Payart's answer makes perfect sense. Besides, he should know, he bought the winning Aprilia RSA125 right after the last 125 cc Grand Prix and today he produces his own, very well-made copies of those cylinders for his 250 cc tandem twin FPE superkart engine.
The port in the cylinder casting has a timing of 196°. Then the upper edge receives a radius that lifts the timing edge to 202°. It's as simple as that.



With a variable header length you do not need to artificially raise the exhaust gas temperature, so you need neither the power jet nor the ignition retard.
The 50 cc engine with trombone pipe that I wrote about some time ago, runs strongly from 7,000 to 17,000 rpm without power jet and ignition retard.

Note: the power jet in the Aprilia RSW / RSA is gradually closed and the ignition is gradually retarded till 10° before TDC. These engines rev to 14,500 rpm. But I am convinced that with a trombone pipe they would function much better still.


Thanks for the flowers, RAW.
You can have an intake length that is too short in combination with intake diameter, intake timing, crankcase volume and desired rpm, in which case the engine will express its displeasure by blowing back some of the inhaled mixture. I prefer to shorten the intake length as much as possible and shorten the intake timing accordingly.
By varying intake length, intake timing or crankcase volume you can adapt the induction system to different rpms. I think the best way to adapt to low revs is to advance the intake closing; it will make for a docile engine with a clean, easy to set carburation.

Varying exhaust pipe length seems to be a far better way of increasing overrev than retarding the ignition or leaning out the mixture; it would be a waste not to utilize all inhaled oxygen. Varying the pipe length can also markedly lower the beginning of the power band.

[TZ350]

Thanks Husa, all good stuff .....


we will need a geometrical exhaust timing of about 190°, depending on the shape of the port: does it open gradually or does it open over its full width all at once.

The obvious question will be: why has the Aprilia RSA125 a geometrical exhaust timing of about 200°? True, at 190° the maximum torque value would be higher, but the engine would not want to rev because the blowdown time.area would be too small.

The 200° are a compromise: a bit less torque and a bit more revs; as long as the torque decline is smaller than the rpm rise, we gain horsepower.

This bit talks about the optimal 190 deg exhaust duration and the blow down compromise.

[TZ350]

275503

This is an old graph but it shows how a pipe that peaked at 10,500rpm can be made to extend the power curve by progressivly shortening it. Although -130mm might be a bit much in mechanical reality.

I want to start about 9k and finish at 12 ish with 30 rwhp. And to do that I need the ports STA's to be right at 12 but they are obviously over sized at 9, we will just have to find a way to live with that.

[TZ350]

Page 680 all ready ...... some more of those pipe posts from Wob and Frits to go here when I sort them out.


With todays technology the bar can now be raised to around 40 crank Hp without too much drama involved, and thus achieving around 35 RWHp.
Its just a matter of careful parts selection and very careful assembly.

The alloy inserts for the TZ350 was the customers choice - once its all proven, and we get a handle on what the engine likes, then I will do some bronze ones.

AvGas in NZ is all LL100, this is low lead 100 octain.But the rating is defined differently in avaition.Its approx equiv to 100 "pump" gas, but has a lean rating of 100 and a rich rating of 130.
MNZ Appendix E defines avgas as max 112 MON amd max 108 RON.

Avgas, or any leaded "race" fuel reacts completely differently to unleaded pump gas.
In general terms the unleaded hates compression, but loves timing.Avgas is the opposite in that it makes more power up to the knock limit with more com.
Unleaded makes better power when run rich,avgas makes more the leaner you go.
Tuning in the old days with RS and TZ engines meant using lean mains and small powerjets ( 35 ) as turning off a big jet over the top would mean being too lean in the overev.
Nowdays the unleaded fuel runs rich at peak power, then uses a big powerjet ( 55) to create some heat in the pipe over the top.


Race gas bought in drums really is" low lead race gas", nothing wrong with it - but hard to get the same stuff in many places.
The stuff in tanks at stations/tracks is "old" avgas.The best, and only way to be sure of what you are getting is to go to any local airport and buy Avgas - it is tested regularly and is guaranteed to be fresh and to spec - has to be, or the Lycomings would all fall out of the air - bad.


One thing I completely disagree with in the piston seizure write up is that air leaks cause a lean condition.
This is utter bollocks, any engine with a case leak will run richer, the bigger the leak the richer it will run.
Caused by the fact that the case "pump" no longer works and the fuel air mixture isnt being transferred thru the ducts.
If the engine is then leaned up to "fix" the incorrect mixture - then it seizes.


A leak between the carb and the reed or any intake will always add air going into the engine and create a lean condition.
A leak anywhere in the case, be it a gasket, a seal, or a pin hole in a casting will cause the engine to run rich.
Problem is that they then seize for no apparent reason when the jetting is then "fixed".
So its always wise to make a set of blanking plates and or use a rubber bung with a bolt that expands it into the pipe manifold, so that a leak down test can ensure no case problems exist.


Everyone uses the chamfered pin with plain clip now - but for years we had to cut the inner leg off TZ clips and add the chamfer to prevent the clips from popping out.
Dont know if Irving was the instigator of the idea, but it works a treat.
The angular contact bearings I dont think are a good idea for mains - as any side float will translate into vertical slop as well, so they must be run with preload.
Sort of the reverse of floating the crank - and thats worth easily replicated free Hp.

Primary com of 1.37 would be about right for the average transfer duct and port geometry being run.
If the descending piston compresses the volume, then its part of the case compression if its connected when the piston port is closed.
That plug looks way too hot for the application as well.


Well its a bit of a stretch to try and be specific with so many variables involved but I will try.
What you are dealing with is a combination of static com and the dynamic com created by the efficiency of the engine spec, along with the added quirk of small bores being able to withstand more of both.
The more an engines overall spec is synergistic and SOTA then the less static com is needed nor is it in fact desirable.
So - with very average port/duct geometry, a very average pipe design, a very average ignition curve but using Avgas, then at the very least we need 15:1 full stroke com to get close to optimum, with EX durations between 196 and 202, where you need to be to make any power at all.
Avgas burns so close to 105 unleaded race gas, in power and reaction to com that its indistinguishable on a dyno, except that Avgas will always withstand more com or a lean condition better. Unleaded hates com but loves timing - as a general rule, the opposite of proper race gas or Avgas.
As Avgas is allowed, and we are discussing small bore race engines with sub optimal ports/pipes etc then I would say around 15.8 would work fine.
On pump gas, be it 91/95 or crap 98 then reduce this to 13.8 and wind in lots of static advance.
Avgas isnt created for what we are doing, but its cheap enough,available at any airport,and works real well when pushed to the edge of the tuning envelope.
The other issue is that to be effective, the squish clearance should be just above what would give zero clearance in an overev situation.
Thus any 50 or 100 cc bucket is able to run down at 0.6mm with complete safety, without running into issues of excessive squish velocity, unless you are well over 50% SAR.
But dont give me any grief when the thing melts using an 8 plug when any engine making any power at all, should have a 10 iridium as a baseline.


Very interesting and Yes I would think it fair to measure 2-stroke CC's that way ........



It appears "compression cannot commence, before exhaust port is closed" untill you think about the role of the expansion chamber.



When you think about the plugging effect of the return pressure wave from the expansion chamber stopping fresh charge from spilling out of the cylinder as the piston starts on its way back up to close the exhaust port and maybe even stuffing some back in, in the last moments of closing.

You can see how compression of the fresh charge can happen earler than the exahust port closing point, effectivly making it a bigger engine when its "on the pipe". Some call it the supercharging effect..... whether it results in more than 100% volumetric efficency of the total swept volume I don't know, but it certainly gives more than a 100% of the swept area above the exhaust port.

There it is, the whole mistery of racing 2-strokes reveled in the last two posts, everything else is just detail, thanks Dutchee.


I think the analysis of the 2T working cycle when compared to the 4T in the example is a bit simplistic and missleading.
A full house 4T like say the Britten V1000 has a VE around 125% and an Ex duration of over 300*.
The 4T uses the exhaust tuning to create a depression during TDC overlap, giving the intake stream a chance to purge residuals out of the chamber.
In a 2T the Ex creates a depression around BDC, giving a Delivery Ratio of 1.25 ( same number effectively as the 4T ) and this purges residuals in the same way as the 4T.
BUT, the 2T uses the open Ex port in concert with the pipe design, to reverse the outflow,shoving clean, overscavenged clean Air/Fuel back into the cylinder, using a duration number closer to 200*.
The real kicker for the 2T is the huge efficiency gained by firing every revolution, doubling the Ex frequency, and thus the energy that can be used to good effect.


It may be semantics but why "change" the calculation of bmep for a 2T by doubling
it because it fires every revolution.
The bmep of a full house 2T is around 200 psi, as this is a calculated relationship between measured torque and displacement.
The calculation is a measure of the ability to produce power PER CYCLE, divided by the number of power cycles.
Thus a 4T has a higher bmep capability, but is hamstrung by the halved number of available cycles.
This is an inherent advantage of a 2T, you cant just factor it away in the calculation.
And the VE numbers are simply a measure of the amount of air ingested per cycle divided by the displacement, and are essentially the same for full noise designs.

Its a bit like the people that go on about the measurement of power on a dyno.
The guys with huge Harley engines say that the power should be "corrected" for the big heavy pieces of shit when compared to a small screamer 125cc GP bike.
The reality is that the big , heavy pieces of shit are exactly that, and what is measured at the rear wheel, is the actual power delivered in the real world.The fact that they have huge flywheels that absorb "power" to spin up, is an inherent
part of the design, and in my opinion cant be ignored by applying some fudge factor that makes them feel better, about the Hp/cc figures.

Page 340

[TZ350]

275504

This is a collection of crank hp simulated graphs (93% combustion efficiency so overstated) of my current RS125 pipe and big port 30 rwhp, estimated 34-35 crank hp motor.

In the simulation the pipe peaks at 12,250 just like it does on the dyno and the simulated torque does not drop off all that much as the pipes header is shortened.

The simulations indicate a 6k power spread is possible but would you really want to rev an old 1978 Suzuki GP125 engine to 15K.

Its the high powered 6k power spread that I want (and yes Wob I know it won't be 40hp).

The simulations have got me interested in the Trombone pipe. I need my new pipe to initially peak lower and finish earlier than 15k.

So I am going to use EngMod2T to try and find out what I might be able to achieve.

[wobbly]

Having the torque peak at a low rpm ,then spreading the power out over a wide band is possible.
But very tricky to make work in practice.
Means several elements are effectively in anti phase, especially where they should work together and create lots of power.
But if you want broad power spread ,this will always limits the peak capability.
The RZ400 could easily do 100 RWHp, but then it wouldnt spin up off turns to anihalate SV650s.
And this is a road bike shitter with 102mm bore centres, that limits you in getting anything remotely like good duct geometry.
This result needs all manner of trickery, and solenoids,ATAC etc etc all are capable of extending things way better than simply good porting and pipes could ever do.

[TZ350]

Developing a virtial pipe using EngMod2T, and then make and test it in real life. I expect it will take a while and no doubt I will flounder around a bit but I am keen to give it a go . The occasional pointer when I am getting lost or off track would be appreciated.

[TZ350]

p412

If I were to explain pipe design I would need to write a book,but in general things are pretty straight forward in relation to the % values.

End of header is always 31 to 33% and end of diffuser is always 62 to 68%.

To see the effect of a silly long header, you can watch the pressure ratio at the Ex port, and thus the effect this has on the depression in the cylinder.

We are looking for the lowest and widest negative ratio we can get around bdc when the transfers are fully open.

A long header delays the beginning of the depression too late in the cycle, when in the power band.

In a race 2T we are always fighting power range Vs peak power.

Shorter diffusers create steeper angles, thus greater wave amplitude, but this narrows the effective band width.

So - in general the best compromise is around 66%.

P413

The % I quoted for header means that portion of the length from piston to rear cone end.

Its from the piston to the beginning of the diffuser, what happens in between isnt relevant.

Unless of course you use a small Ex duct and a bigger header, that makes more power.
And of course same for the diffuser end, that is simply 66% of the length from the piston to the end of the rear cone.

So to start with, I understand some of the key elements are.

(1) The end of header is always 31 to 33%

(2) The end of diffuser is always 62 to 68%.

(2) We are looking for the lowest and widest negative ratio we can get around bdc when the transfers are fully open.

Time to warm up my EngMod2T program and use the Pipe Development part of it to get started.


In a race 2T we are always fighting power range Vs peak power.

Shorter diffusers create steeper angles, thus greater wave amplitude, but this narrows the effective band width.


The plan is a peaky pipe at 9k rpm and to extend its range using the Trombone effect.

[husaberg]

oh got that wrong more than usual.......:clap:
can't find the post either ROB but found these.........

I thought, though likely wrong that the trombone shortens to gain over rev.Rather than lengthens to gain low end power???????
i certainly are no expert :weep:but it took me a while to get my head around that it may be better to first aim for the peak that you want.
(This is two strokes in general) i think it came from Wob or Frits, when i asked about trying to spread the power by tuning say inlet to a sightly different rev than say exhaust
it was said that it was better to use cunning tricks like solenoid carbs and ignition tricks and maybe a trombone pipe to spread the power by increasing the over-rev. rather than using other methods to broaden the power down low. but i am pretty sure this is a half quote probably out of context.........
i think this was the one i was looking for

You have to stay within certain length percentage limits for all elements of the exhaust system; you cannot make one part a lot longer or shorter in relation to the others without losing power somewhere.
It is best to concentrate on getting all dimensions correct for maximum power. In the high gears you don't ride low revs and in the low gears you'll have enough low-down power left to pull a wheelie or spin out the rear wheel (I'm not talking about buckets though, so you might want to reconsider your case).
If you have a decent setup for angle*areas, pipe, carburation and ignition, the necessary overrev potential will come naturally; no need to sacrifice maximum power in order to make it rev a little higher.
Although this was before the advent of the trombone pipe i think

Jan was talking about coolant passages inside the inner curvatures of the transfer ducts. I have no pictures of those (cutting RSA cylinders in half would be a bit of a costly hobby) but here is a picture of my FOS cylinder with the same coolant ducts.
this was the post where Frits showed the beautifully made FOS cylinder with the pictures well worth going back and having another look.

Here are some of the pictures. Most of them have not been shown on an open forum before.
Pictures 1 and 2 show development stages; both are several years old now.
Picture 3 shows doctor of physics Denis Klemm (left) and myself with the first 50 cc FOS cylinders. Denis was of vital importance in applying the Selective Laser Melting process that allowed me to produce the shapes I wanted.
http://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=250215&stc=1&thumb=1&d=1320582517http://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=250214&stc=1&thumb=1&d=1320582521http://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=250213&stc=1&thumb=1&d=1320582525http://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=250212&stc=1&thumb=1&d=1320582528
Pictures 4, 5 and 6 show these cylinders from some different angles.

on a passing note someone made a comment about the asians ripping off the the europeans in regards to scoooter stuff.
Well i found this funny.


Boost bottles
........
This could be accomplished with a diaphragm. Much like a pressure vessel on a Water pump you could even plumb it with a butterfly valve.
Could this be a create an effective Plenum chamber? Down steam from the carb.
Also a variable factor to crankcase volume? Musing aloud here. A lot of could's and Ifs but..............

I linked a site on the post in the next post as an example of some different boost bottles. Well now when i was going back (looking for frits post) i looked at the link well now they have variable size boost bottles :killingm
http://www.sip-scootershop.com/files/catalogue/index.html#/309

[Frits Overmars]

Frits i think you way have misunderstood my question.....Yes, I misread it; sorry about that.

The request to ask Jan (if it was all right as a courtesy) for me to post some of Jan chassis pictures he had shared out of another thread, may be better received from his friend.Probably. But then Jan would probably ask me which pictures exactly, and I wouldn't have an answer. You are right about the courtesy, though.
But anyway, when Jan posts something on an open forum, you may safely assume that he won't mind you using it. And the same goes for me.

The Excalibur project i assume failed.... but i can find only brief mentions of it in the press.....Do you recall the English project? No, I don't.

[Frits Overmars]

This is the perfect time for me to step in and tell you to stop dreaming. 40Hp at 9,000 for a 125cc engine = 16Bar = 230 psi bmep.
ABSOLUTELY IMPOSSIBLE, NEVER BEEN EVEN REMOTELY APPROACHED, AND NEVER WILL BE.
New Years Wake Up Call.New Year's Encouragement Call:
Aprilia RSA125:
maximum power: 54 gearbox-HP @ 13000 rpm
maximum torque: 29.75 gearbox-Nm @ 12517 rpm
By definition the Brake Mean Effective Pressure is the constant pressure, working upon the piston, that would yield the same power or torque value as produced by the engine.
So to find the RSA's maximum BMEP first we must convert the gearbox-torque to crankshaft-torque.
Calculating with 5% loss in the primary transmission and 5% loss in the gearbox, we will find a maximum crankshaft torque of 32.725 Nm.
That gives us a BMEP of 32.725 * PI * 20 /124.8 = 16.47 bar (derivation: see http://en.wikipedia.org/wiki/BMEP).
So it can and has been done. But it ain't easy. And without liquid cooling I wouldn't even try :no:.

[husaberg]

Yes, I misread it; sorry about that.
Probably. But then Jan would probably ask me which pictures exactly, and I wouldn't have an answer. You are right about the courtesy, though.
But anyway, when Jan posts something on an open forum, you may safely assume that he won't mind you using it. And the same goes for me.
No, I don't.

No worries the fact that so many Europeans can so readily swap between so many languages never fails to amaze m e while we kiwis struggle at time with one,
<img src="http://www.deraceheldenvanweleer.nl/index.php?PHPSESSID=bbobq0gv5ajsklgubq0c2ehnu0&action=dlattach;topic=51.0;attach=16539;image" width="510px"/><img src="http://www.deraceheldenvanweleer.nl/index.php?PHPSESSID=bbobq0gv5ajsklgubq0c2ehnu0&action=dlattach;topic=51.0;attach=16607;image" width="510px"/>
<img src="http://www.deraceheldenvanweleer.nl/index.php?PHPSESSID=bbobq0gv5ajsklgubq0c2ehnu0&action=dlattach;topic=51.0;attach=16612;image" width="510px"/><img src="http://www.deraceheldenvanweleer.nl/index.php?PHPSESSID=bbobq0gv5ajsklgubq0c2ehnu0&action=dlattach;topic=51.0;attach=16608;image" width="510px"/>
<img src="http://www.deraceheldenvanweleer.nl/index.php?PHPSESSID=bbobq0gv5ajsklgubq0c2ehnu0&action=dlattach;topic=51.0;attach=16613;image" width="510px"/><img src="http://www.deraceheldenvanweleer.nl/index.php?PHPSESSID=bbobq0gv5ajsklgubq0c2ehnu0&action=dlattach;topic=51.0;attach=16788;image" width="510px"/>
<img src="http://www.deraceheldenvanweleer.nl/index.php?PHPSESSID=bbobq0gv5ajsklgubq0c2ehnu0&action=dlattach;topic=51.0;attach=16789;image" width="490px"/><img src="http://www.deraceheldenvanweleer.nl/index.php?PHPSESSID=bbobq0gv5ajsklgubq0c2ehnu0&action=dlattach;topic=51.0;attach=16790;image" width="640px"/>


Another drawback was the lack of fuel supply as the "tank" almost
was empty, there was too little height difference between the "tank level" and
the float chamber level. We have that Minarelli solved by a
small 'funnel' to the nose fairing and this set than with a
tube the "tank" under pressure. After that time never had problems with it.
http://www.deraceheldenvanweleer.nl/index.php?PHPSESSID=bbobq0gv5ajsklgubq0c2ehnu0&action=dlattach;topic=51.0;attach=16611;image

[ief]

Tuff cookie to crack teezee, how you're getting along?

[wobbly]

The impossible part of the bmep equation I was alluding to was trying to achieve 40 Hp at only 9000.
As you point out Frits it is achievable at 13000, but only with every tuning advantage known to man, along with optimum duct shapes etc.

[TZ350]

Tuff cookie to crack teezee, how you're getting along?

Hi Ief

I am pretty confident that by using a trombone pipe arrangement, that a pipe designed to give its best at 9,000 rpm can be made to carry the peak on to 12,000 but it is going to take some time to work through the development process.

[ief]

Tell me about it ;)

My efforts thus far, your shown setup with some (verry) small changes. I took my approach and went for a steady torque curve as long and high as possible...

Wonder what the setup would do with a proper normal exhaust btw.

Bit high in the rev range perhaps but anyway...

oops > edit: trombone with 60 mm travel.

[SS90]

Hi Ief

I am pretty confident that by using a trombone pipe arrangement, that a pipe designed to give its best at 9,000 rpm can be made to carry the peak on to 12,000 but it is going to take some time to work through the development process.

There are a few of us that sincerely hope you can make a trombone exhaust work, however, I think it prudent to remind you that to a flat power curve it is not necessary to have a trombone pipe, or any other expensive (but nice to have) part.
It can be achieved with EXPANSION CHAMBER DESIGN, cylinder head design, and a basic reading ignition. (no power jet carb, or any other such item).
By all means, make a trombone pipe, but I have shown before you can achieve the power needed to beat 4T 150cc with conventional set up, and I would like to see ESE actually put up a fight on the track.

I would have thought an ATAC header set up would be easier to achieve, and of more benefit that a trombone pipe, it is something I have worked on myself (ATAC, not trombone, as Engines I build have curved headers, making a trombone header not possible), and they can, and do work wonders... As Wobbly has already mentioned numerous times.

Quite some time back, someone (cant remember who) posted a very old article that Frits had written, regarding expansion chamber design, I recommend that you consider this priority reading, while it is not in English, learning another language is par for the course for some of us, and if that is not realistic, a few hours with a dictionary and pen and paper, you will be able to understand everything he mentions, it goes someway to explaining how to get the type of power curve you have finally decided to aim for.

There is a fundamental design difference between the exhaust you have been using (RS125), and
One that will enable the power curve you want.
Yes, it will bring it's own set of headaches (ones that many of us have had to deal with), And I personally am keen to see how you resolve them, but like I say, go to the effort of translating that article. It will point you in the right direction.

I find Germanic languages reasonably easy learn when reading, as many technical words are somehow logical in their root, and technical information is logically written, Dutch and Flemish (particularly) is quite hard, but they do follow a logical pattern in their syntax. When you start the article, start a side column building vocab (the single most important process in learning a language), and by the second page, you will already have learned a minumum of 20% of the necessary vocab (likely more, as technical articles are, by nature on one subject).

[TZ350]

Hi Ief, it looks good and I am sure the idea can be made to work.

At the moment I am still getting to know how EngMod works. One of the mistakes I made was designing a pipe for 600 deg and I didn't realize I also needed to enter that number in the "Edit Temperature Data" file before running the simulations and wondered why my simulations peaked at a rpm that was a touch higher than they should have. So I have a bit to learn about pipes and how to use EngMod to design and simulate them.

[TZ350]

I think it prudent to remind you that to a flat power curve is not necessary to have a trombone pipe

It can be achieved with EXPANSION CHAMBER DESIGN, cylinder head design, and a basic reading ignition.

I have no doubt that's true and have seen some impressive dyno graphs but they were limited in range, they had a 3,000rpm spread at best.

275540

I currently have about a useable 4,000 rpm spread.

I am looking to plump up the lower part of the power curve and widen it for a flater high powered 6,000 rpm wide power spread which I am sure can be achieved with a trombone pipe.

If you can post any graphs from a fixed pipe that have a high powerd flat 6k power spread I would be very interested in seeing them.

[SS90]

I have no doubt thats true and have seen some impressive dyno graphs but they were limited in range, they had a flat torque curve for 3,000rpm at best, I currently have about a 4,000 rpm spread.

I am looking for a high powered 6,000 rpm power spread which I am sure can be achieved with a trombone pipe if you can post any graphs from a fixed pipe that look like that I would be very interested in seeing them.

Having built and raced these engine for a few years now, I can assure you that the power spread you need is achievable with what perifrials and facilities you currently have, I agree that extending the rev range higher than 10,500 is desirable (and again achievable), that is evryones goal, but I suggest that if you aimed for a starting point you can develop from (the current cylinder is, from what I see a major step in the right direction.

In regards to expansion chambers, I started in Winter 2007 using a dyno graph from an engine that a friend from A major Euro bike manufacturer built, and used that was my bench mark, (and with his help, I beat the peak power, but never the massive mid range...actually, still have not managed to come close to that, or the massive over rev) one if his (many) big hints was to look at
Motocross and enduro expansion chamber designs, and compare them to the peaky RS125 pipe designs I was trying to use. This will also help you.

Remember, you only have 5 available gear ratios.... With the right exhaust, this is in someways an advantage, with the wrong exhaust, a big disadvantage.

[TZ350]

Having built and raced these engine for a few years now.....

I admire your enthusiasm and capacity for talking but I would be more impressed with a 6k wide power graph from a fixed pipe.

[ief]

With regards to ex wall temp input. On the rd/rz files a good figure seems to be 55 degrees, seems like a bodge and perhaps it is but I'm told that's what it needs. If I'm right Wob provided some of your files and perhaps the temp file as well? If so i'd suggest use those.

Best way would be to use one of your known designs and dyno curve and match them up?

With regard to the fos exhaust article, allready posted here once but there are imho more current, more detailed and above all, more english pieces to be found.

- Randy Norian, rg 500. -

[husaberg]

Somewhere there is an overlay of Mikes Vs Robs power curves 30hp
I don't know weather its still (true given the current state of RSW/RSA knowledge we now have access to.)
But i can remember Wob adding while the max HP will always be lower with a similarly developed reed valve vs a Disk valve the power spread will be better with a reed valve.(makes sense)
the problem Rob would have is the pesky reeds i guess would restrict his flow.(possibly more so with a 24mm carb.)
Wob mentioned the revs the honda 250 twin (which would mean a longer stroke than Robs) ran to and While speedpros stroke is shorter (48.5 or so?) i think rob may have more luck aiming for a higher level of revs. say 10000rpm power-peak.
you have a RGV rod and bearing i guess they are good for plenty of revs........

<img src="http://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=247544&d=1317179895" width="700px"/>

On a HRC - RS250 for example the solenoids are activated at 12200 to 12800 ( adjustable plugs in the loom) and it will rev hard to 14000.Without the powerjets it falls dead just past peak power at 12000.

Bottom line is that when tuned for max power the disc valve does make more than a reed - those flapper things are always "in the way" to some extent..
But there are many trade offs.The disc will have NO power at all under the tuned for range, as it cannot suppress reversion at low rpm, and you cannot tune out the fact that the intake waves are telling the main jet signal all manner of lies,repeatedly.
Thus a reed engine can have much wilder exhaust timing and pipe design without giving away a heap of "under the pipe" power, and this exhaust tuning can have plenty of overev power as well, if that's what is needed.
An example would be the pipes I did for the fastest,and record breaking Honda RS250 on the salt last year, it had over 90RWHp between 12000 and nearly 15000,so would simply keep revving till the aero drag stopped it.
The peak power was "only" 96 I think, but it had plenty everywhere else it was needed.
To get that sort of overev power from the RV would mean it would be all but impossible to get it to carburate off the pipe, as the closing timing needed to get to 15000 would be mentally wild ( like 98*+ ).
And the last thing to consider is that despite what the supremely clever Frits and Jan say and did - in the last year of 250GP a Honda reed valve engine kicked Aprillias arse in the title - with a guy who cant ride a MotoGP bike to save himself.
The newer RSA engine is probably an unbeatable combination in 125GP, but for many other less demanding applications the reed has real, and useable, advantages.

But what would i know....................
What ever hapened to the TS RGV motor Rob.
http://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=231955&d=1297494329
this i think was a Speedpro Motor?

oh maybe i was to hasty with Robs decision to maybe go back to unleaded.........

With today's technology the bar can now be raised to around 40 crank Hp without too much drama involved, and thus achieving around 35 RWHp.
Its just a matter of careful parts selection and very careful assembly.
AvGas in NZ is all LL100, this is low lead 100 octain.But the rating is defined differently in avaition.Its approx equiv to 100 "pump" gas, but has a lean rating of 100 and a rich rating of 130.
MNZ Appendix E defines avgas as max 112 MON amd max 108 RON.
Avgas, or any leaded "race" fuel reacts completely differently to unleaded pump gas.
In general terms the unleaded hates compression, but loves timing.Avgas is the opposite in that it makes more power up to the knock limit with more com.
Unleaded makes better power when run rich,avgas makes more the leaner you go.
Tuning in the old days with RS and TZ engines meant using lean mains and small powerjets ( 35 ) as turning off a big jet over the top would mean being too lean in the overev.
Nowdays the unleaded fuel runs rich at peak power, then uses a big powerjet ( 55) to create some heat in the pipe over the top.

[SS90]

I admire your enthusiasm and capacity for talking but I would be more impressed with a 6k wide power graph from a fixed pipe.

I would be impressed with ESE winning, and still stand behind the notion that from what I see, such an engine is not required to win.

Horses for courses I guess, but for me, the idea of racing is to win, not at all costs, but at least a chance makes it fun.

I have my opinion, and you have yours.

You are being beaten by mid 20 HP engines with big spreads and you could easily build an engine with better (at the very least comparable) power, and it would be less stressed than now to.

If you want to build a reliable high specific power engine, maybe a water cooled hundy is the best option, that would change the field again.

[TZ350]

I have my opinion ...

I am sorry to have to tell you, but it probably doesn't matter what your opinion is.

I have a development objective and if you want to, you can contribute to achieving that in a positive way with real information if you have it.

[cotswold]

I would be impressed with ESE winning, and still stand behind the notion that from what I see, such an engine is not required to win.

Horses for courses I guess, but for me, the idea of racing is to win, not at all costs, but at least a chance makes it fun.

I have my opinion, and you have yours.

You are being beaten by mid 20 HP engines with big spreads and you could easily build an engine with better (at the very least comparable) power, and it would be less stressed than now to.

If you want to build a reliable high specific power engine, maybe a water cooled hundy is the best option, that would change the field again.

To be fair to ESE the rider on the bike at present is over 50 and is riding it for fun as he knows he has to go to work monday morning, I am sure some young lad would be a lot faster.
Any positive input you can share with us would of course be gratefully received but until then STFU. just my opinion

[FastFred]

Having built and raced these engine for a few years now ...

So you keep telling us but from your recent conversation with Wax you displayed some alarming gaps in your knowledge regarding CVT's for someone who holds themselves out as an experienced Scooter tuner.

[Farmaken]

[QUOTE=TZ350;1130459015]I am sorry to have to tell you, but it probably doesn't matter what your opinion is.

That there is pure gold

:killingme

[tdc211]

I have been following this thread. Here is my output shaft steel wheel dyno chart of my mx piped engine, a few ccs over 100.

[kel]

I have shown before you can achieve the power needed to beat 4T 150cc with conventional set up, and I would like to see ESE actually put up a fight on the track.

Did I miss something? I would have thought the ESE team and bike achieving 9 wins from 9 starts was a bit more than "actually put up a fight on the track", in my book the ESE team have already knocked out the opponents, TZ now wants to stick the boot in.

[TZ350]

I have been following this thread. Here is my output shaft steel wheel dyno chart of my mx piped engine, a few ccs over 100.

Interesting dyno graph, thanks for that......

[Yow Ling]

I have been following this thread. Here is my output shaft steel wheel dyno chart of my mx piped engine, a few ccs over 100.

Looks great, can you throw us a few more crumbs please mister?

[husaberg]

I have been following this thread. Here is my output shaft steel wheel dyno chart of my mx piped engine, a few ccs over 100.

Its does look impressive ,i too would like further information, how many is a few cc's.
You could be from Texas after-all.:whistle:

[TZ350]

Ok all packed and on our way to Taumarunui.

[tdc211]

Its does look impressive ,i too would like further information, how many is a few cc's.
You could be from Texas after-all.:whistle:

107cc's I guess that is more than a few. Maybe not all that impressive. But was built for MX.

[Bert]

I have been following this thread. Here is my output shaft steel wheel dyno chart of my mx piped engine, a few ccs over 100.


107cc's I guess that is more than a few. Maybe not all that impressive. But was built for MX.

Please tell us a little more. is that a big bore kitted CR85?

Maybe even a port map / listed durations might be interesting for some of us.

Nice work though ~300hp per litre. :2thumbsup


Dredging up information:

Its the old story of simply moving the weakest link from one area within an engine to another.
Basic bearing operation dictates that full compliment needles will handle a heap of load, but are ultimately limited, in that the rollers are all rubbing on each other
and this leads to failure.They also cannot handle ANY movement away from dead true in any plane, as they then skid even more rapidly.
Having the big end well open with alot of clearance around the rod and cage helps access by the oil film and makes this area pretty bullet proof. with no washers in the way.
But this then moves the point of most wear up to the location washers in the piston.
In a KT100 the versions with alloy washers in the small end will have wear marks on these washers in a very short time, the small end being caged makes it bullet proof,and
the open rod big end lasts well, until the cage wears on the rod bore.
In the end it is the rod big end cage wear that forms the limiting factor, and it has been found by thousands of engine rebuilds, that the silver coated big end cage and washers have about the same ( acceptable ) limiting
lifespan - the open, caged small end lasts forever in either case.
Simply removing the washers is plain dumb - I have seen a couple of new crank designs done this way just recently, both failed very badly with lube failure around the rod big end - IT DOES NOT WORK, reliably.
Thus having the washers down the bottom becomes a known factor - replace them when you replace the cage.
The rod and pin will usually take around 4 bearing replacements.
Iin fact if you could buy them, simply replacing the cage ( with the washers as well ) would mean you could keep the rollers - for the life of the rod.

Wobby (or Frits): how many hours would you expect to get out of big end bearing (thus rod life as well) in a racing engine application?

I've been slowly formulating a replacement plan for different engine parts..

[husaberg]

A technical explanation? Nah, too much to do today. But since you were kind enough to post that picture of your sex six sisters, I will show some curves of my own.
When Jan Thiel went to Derbi to design the bike we now know as the Aprilia RSA125, he encountered the 125 cc reed valve Derbi ridden by Lorenzo the previous season. Jan played around with the reed valver as well, because he wanted to find out the differences between reed valve and disk valve power. He managed to extract 2 HP more from the reed valver than anyone else had ever done before (never mind the fairy tales of reed valve 125s producing over 50 HP; those Horses must have been Shetland ponies, probably measured at the piston ring).
My graph shows the power curve for the Aprilia RSA, the Aprilia RSW and that best-ever reed valve Derbi. It's not quite in the same league as the rotaries, hmm?

EDIT: Shame on me; I discovered that I posted a wrong graph (and I do not have the correct one at hand here in Holland). Power curve DERBILOR shows the reed valve Derbi as Lorenzo rode it. After Jan finished playing with it, it had 49 HP. Still, the best-ever disk valver produced 10 % more power than the best-ever reed valver.

http://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=261462&d=1333621581

Bottom line is that when tuned for max power the disc valve does make more than a reed - those flapper things are always "in the way" to some extent..
But there are many trade offs.The disc will have NO power at all under the tuned for range, as it cannot suppress reversion at low rpm, and you cannot tune out the fact that the intake waves are telling the main jet signal all manner of lies,repeatedly.
Thus a reed engine can have much wilder exhaust timing and pipe design without giving away a heap of "under the pipe" power, and this exhaust tuning can have plenty of overev power as well, if that's what is needed.
An example would be the pipes I did for the fastest,and record breaking Honda RS250 on the salt last year, it had over 90RWHp between 12000 and nearly 15000,so would simply keep revving till the aero drag stopped it.
The peak power was "only" 96 I think, but it had plenty everywhere else it was needed.
To get that sort of overev power from the RV would mean it would be all but impossible to get it to carburate off the pipe, as the closing timing needed to get to 15000 would be mentally wild ( like 98*+ ).
The newer RSA engine is probably an unbeatable combination in 125GP, but for many other less demanding applications the reed has real, and useable, advantages.

Frits re the dyno curve, do you have access to the updated one (after Jan had caressed the reed valver a bit more)
(i are also assuming the same exhaust was used) was it?or is it a overlay comparison of the final development of each minus Jan last mods to the reed valve Derbi.
i ask this aware that the RSA was developed initially at Derbi.
So if this is the case using Wobs explanation or a disk vs Reed does that mean that the reed valve Derbi could have been lifted maybe a little more to close the gap a little more with possibly a little more over-rev as well with more radical exhaust pipe and timing, or is it the very best that Jan could possibly do (within reason)with the Reed valve Derbi? (I ask this because you used the term Play;)) is the potential low drive-ability gains from a reed masked by the 9000rpm start because the curves are eerily similar?(other than the flatter peak of the Derbi reed) Granted a GP rider wouldn't use less than 9000rpm.

A more brutal/abrupt power delivery is something i have always noticed when riding Disk valve engines compared with similar power reed valve engines....

Lastly were you ever able to retrieve the SAE papers that Fleck submitted regarding Water injection?

sorry that is an awful lot of questions .

[Frits Overmars]

Extracting 49 gearbox-HP out of the reed valve Derbi was the best Jan could do. I must have the curve somewhere at home, but I am not.
There were several pipe modifications but I don't remember which pipe gave those 49 HP. It's eight years ago...


Is the potential low drive-ability gains from a reed masked by the 9000rpm start because the curves are eerily similar?(other than the flatter peak of the Derbi reed) Granted a GP rider wouldn't use less than 9000rpm.A GP125-rider spotted below 10,000 rpm ought to be fired.


A more brutal/abrupt power delivery is something i have always noticed when riding Disk valve engines compared with similar power reed valve engines....Maybe when it comes into the power band. But then that would be your own fault; you should keep it in the power band at all times. And once in the band a disk valve engine's throttle response is much more linear and thus more sympathetic than a reed valver's. If not, you should work on your carburation.


Lastly were you ever able to retrieve the SAE papers that Fleck submitted regarding Water injection?No, and I didn't bother either. We gathered experience with water injection long before Bob Fleck did, and it taught us that although bottom power becomes a lot better, it doesn't do any good to lap times. So it's no use dragging the extra complication around.

[Frits Overmars]

Wobby (or Frits): how many hours would you expect to get out of big end bearing (thus rod life as well) in a racing engine application?I can only speak for the Aprilia RSA: its big end bearing is bulletproof. On the test bench it lasts a full season. But on the track it all depends on the rider.
Flashback: when leaded fuel got banned in GP racing, the Aprilias went from a 19.5:1 compression ratio to 14:1. Works riders Harada and Rossi had no problems (on the contrary: the engines became much more flexible) but Capirossi suffered one big end failure after another.
The datalogger revealed the reason: when signor Capirossi came upon a slow corner, he shifted down three times and then grabbed the front brake. In that order. Engine braking they seem to call it. Engine breaking more like...
With the previous 19.5 compression ratio engine braking was such that the revs went up to 15,000 for a moment. But with the 'unleaded' compression ratio Capirossi's engine revved to 17,500. Bye bye big end :facepalm:.

[husaberg]

I can only speak for the Aprilia RSA: its big end bearing is bulletproof. On the test bench it lasts a full season. But on the track it all depends on the rider.
Flashback: when leaded fuel got banned in GP racing, the Aprilias went from a 19.5:1 compression ratio to 14:1. Works riders Harada and Rossi had no problems (on the contrary: the engines became much more flexible) but Capirossi suffered one big end failure after another.
The datalogger revealed the reason: when signor Capirossi came upon a slow corner, he shifted down three times and then grabbed the front brake. In that order. Engine braking they seem to call it. Engine breaking more like...
With the previous 19.5 compression ratio engine braking was such that the revs went up to 15,000 for a moment. But with the 'unleaded' compression ratio Capirossi's engine revved to 17,500. Bye bye big end :facepalm:.

Maintenance schedule for the RSA.

Here.
Let's hear it for Mental Trousers: he created a way for me to upload BIG files.
I will be offline for a couple of days, but this might keep you busy:

http://www.kiwibiker.co.nz/manual/Aprilia-1.zip

One request:
Don't spread the contents all over the world wide web.
Then I might upload some collected data of other racing brands as well.

Enjoy.

Now this is a bucket racer/kart track friendly dyno curve.
This could cut down the changing around mt Welly
http://www.deraceheldenvanweleer.nl/index.php?PHPSESSID=bbobq0gv5ajsklgubq0c2ehnu0&action=dlattach;topic=51.0;attach=17843;image

I had a look through the RSA125 and RSW125 manuals i was surprised to see the RSA has a much larger o ring on the disk valve cover.120 vs 126mm
Does this mean that the Rotary valve on the RSA is 4-6mm larger in diameter than the RSW or just the o-ring is out further?
I always assumed they were the same size?

interesting ignition overview.http://www.jetav8r.com/Vision/Ignition/CDI.html
modifying a Kawa CDI think its been posted ages ago...http://www.geocities.com/a57ngel/moto/CDI-mod.html
.

This http://www.geocities.com/a57ngel/moto/CDI.html talks about repairing/modifying a KDX CDI's retard curve, there is also a schematic.


Frits Overmars Pitlane
In a 125 cc race engine the spark-plug sparks at about 14° BTDC @ 13000 rpm. Then combustion starts really slow: after the spark another 10° go by before you can detect the first signs of combustion. Then combustion continues for a little over 40° (this is at full throttle; with less cylinder filling, combustion is a lot slower).

Is it useful to slow down combustion on some operating phases? Yes and no. I will try to explain this in a little physics lesson.
No matter which way the piston is moving, as long as there is combustion, the pressure in the cylinder keeps rising. Only after combustion is finished the expansion of the burnt gas can begin.
Slow combustion means that the piston is already well on its way down before expansion can begin; it means less expansion for the burnt gas in the cylinder before the exhaust ports open.
Less expansion means less cooling down of the gas in the cylinder: it is still hotter when it enters the expansion chamber. In hotter gas the speed of sound is higher and that means a higher resonance frequency for the cylinder-pipe system, so it works better at high rpms.

But how do you slow the combustion speed down? Less squish? Mixture too rich? You do not want to do that...
Fortunately there is a simpler solution. We do not slow combustion down; we just start it later: we retard the ignition timing. As far as the exhaust gas temperature in the expansion chamber is concerned, the effect is the same: the engine runs better at high revs.
That is the reason for programmable ignition systems.
Below the power band the ignition advance can be more than 30° so that there is a whole lot of expansion; the burnt gas contains hardly any energy when it enters the exhaust pipe, so the exhaust pulses that arrive at the wrong moments at low rpm, are weak and will not disturb the scavenging too much.
At the rpm of maximum torque the ignition advance is about 14° (careful, a litte too much advance here and you get detonation), and at maximum revs the advance can be 10° or less (Honda even went to 3° after TDC ).

[cotswold]

The beast with it's toned down cylinder finished Taumarunui with engine and rider intact. This was not to say Tee Zee sat on the fence watching his bike go round all weekend though.
It was evident after the very first practice run that the engine was nice and easy to ride but had an issue that would cut our trip short very quickly if not addressed. The engine was suffering from quite severe detonation issues near the end of it's power band and into over rev. TZ played tunes on the carburettor all day on the Saturday, Rob will have to tell what he did but it was extensive. Ultimately we had to go up a couple of teeth on the front sprocket to try and stop the red light telling me all was not well and it enabled me to get the beast into a couple of lonely 7th places.
Race 1: I had a great start and was right with the leaders but the main that was put in before the start was a genuine item and not a knock off and it flowed way more and became impossible to ride and bogged badly on gear changes so I pulled out.
Race 2: 15 laps An uneventful 7th but had to ride to the det sensor which left a fair few rpms still unused
Race 3: 20 laps a carbon copy of race 2.

[TZ350]

Tim did a great job of peddling the bike and giving me feed back so we could get it setup for racing the next day.

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While working the dyno by myself it was a bit hard to tell at what rpm detonation was happening, I really need to video the runs so I can play them back and see the red det light and computer screen at the same time.

Anyway as best as I could tell, on the dyno, the deto that was happening was well into the over rev range. So I hoped it would not be a problem on the track.

Just before leaving for Taumarunui I retarded the whole ignition map 2 deg and set the automatic detonation retard to another 4 deg and crossed my fingers.

But as it turned out the bike was topping out down the front straight and flashing the deto light big time. I could see the deto light from the side of the track as Tim went past and on occasions hear the deto too.

So we upped it a few jet sizes, were using after market Keihen style jets and went up in steps from 135 to 160 but was still getting deto in the over rev region.

The next thing was to up the front sprocket to stop it over reving in top, we went up one then two teeth on the front, that didn't work either, I guess Tim was getting faster.

The next move was a smaller air correction jet to richen up the fuelling on over rev, no luck, still got deto on full throttle in the over rev area.

We had changed a lot of main jets and were starting to suspect the new needle was too fat and restricting fuel flow in the main jet range.

Next move was a really big jet, a genuine Keihen 170 and that flooded so bad that every time Tim backed off it was like putting the brake on and Tim sensibly retired from race one so he didn’t get rammed from behind and take someone else down. But it did cure the deto problem.

We fitted a 165 after market jet and that ran ok but still with deto on over rev.

Our thoughts at this point are:-

(1) After market Keihin style jets are not the same as the genuine ones, no surprises there I guess. In fact the only difference between an after market 135 and 165 may just be the number stamped on the side.

(2) B10H plug and an extra 4 deg auto retard on top of the TPS retard map did not cure the deto, so probably not an ignition timing or plug thing.

(3) Deto in over rev, may mean, not enough blowdown time area for those rpm, Frits and Wob talked about that.

(4) I might have to look at some way of automatically dumping pressure out of the expansion chamber when detoing in over rev.

But I do know I am going to buy a range of genuine Keihen main jets as I have lost faith in the after market ones.

[TZ350]

I have shown before you can achieve the power needed to beat 4T 150cc with conventional set up ...

I must have missed that, does anyone else know where to find it???



I would like to see ESE actually put up a fight on the track.
Did I miss something? I would have thought the ESE team and bike achieving 9 wins from 9 starts was a bit more than "actually put up a fight on the track" ...

Thats true, Avalons bike that Chambers prepaired for her with Thomas and Bucketracers help annihilated everything when she took it out, its just a pity she is to busy riding in other classes to have been able to bring her F4 Bike to the recent Bucket meetings.

[TZ350]

The boys got the Kart clubs scales working so, here are some of the F4 bikes at Taumarunui and their weights.

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Str8s basicly stock 14rwhp (aprox) FXR150 ... 102kg

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Crazymans hot 22 rwhp (I think) FXR150 ... 105kg

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Just for Richban, a picture of a Colt Cams sticker. (the Griffiths boys made me do it) ... :innocent:

Rich's FXR/MC21 is 24rwhp and reputed to be ... 89kg (comment from Rich "Andrews RS is 85/87 I think")

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AC Snows fast Honda framed TF125 ... 93kg

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Henk and Rick52s sidecar ... 112kg

[TZ350]

Taumarunui 2

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Water cooled TF100 CrazyMan 2T ???? rwhp ... 82kg

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Kobas MC18 framed MB100 special rwhp??? ... 89kg

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FarmerKen's MC18 TF125 rwhp???? but fast ... 85kg

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Regans 24 rwhp FXR150 special ... 84kg

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Rick52's 21 rwhp RS TF125 special ... 75kg

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The Beast 27 rwhp 3LN FZR Suzuki GP125 ... weight ??????

[SS90]

I must have missed that, does anyone else know where to find it???



Thats true, Avalons bike that Chambers prepaired for her with Thomas and Bucketracers help annihilated everything when she took it out, its just a pity she is to busy riding in other classes to have been able to bring her F4 Bike to the recent Bucket meetings.

As I understand it (correct me if I'm wrong) the bike that Avalon was riding was 24HP, with a different pipe and suitable blowdown time.

[TZ350]

North Island Round 3 results from Taumaranui

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A Grade.
275879

B Grade

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Side Cars

[crazy man]

North Island Round 3 results from Taumaranui

275878

A Grade.
275879

B Grade

275877
Side Carsthanks for posting this tz ps my bike is around 22 rw hp

[richban]

Just for Richban, a picture of a Colt Cams sticker. (the Griffiths boys made me do it) ... :innocent:

Rich's FXR/MC21 is 24rwhp and reputed to be ... 83kg


Bless. At Manfield I will be bring some Kelford stickers for them. Mine is 89kg at the mo. Andrews RS is 85/87 I think.

[richban]

As I understand it (correct me if I'm wrong) the bike that Avalon was riding was 24HP, with a different pipe and suitable blowdown time.

More like 26 /27.

Don't forget the rider guys. The rider has quite a lot to do with it.

[SS90]

More like 26 /27.

Don't forget the rider guys. The rider has quite a lot to do with it.

Im not forgetting the rider at all there Rick, just continuing the idea that less is more as far as power goes. I really was certain that the bike Avalon was riding had 24HP, but it goes to show that the race wins for ESE have all come on the shoulders of the lower side of the maximum power, and as a result gained rideabilty.

Am I correct in saying the fast 4T engines have around 24 HP at around 11,000 RPM?

[FastFred]

Its not just about reliable hp and rider and ride-ability of the bike, there is another essential piece to the jigsaw that only TeeZee and more so RMSEng have been talking about.

[richban]

Im not forgetting the rider at all there Rick, just continuing the idea that less is more as far as power goes. I really was certain that the bike Avalon was riding had 24HP, but it goes to show that the race wins for ESE have all come on the shoulders of the lower side of the maximum power, and as a result gained rideabilty.

Am I correct in saying the fast 4T engines have around 24 HP at around 11,000 RPM?

24 at 12500. At the moment.

[SS90]

[/I]
24 at 12500. At the moment.

That is quite easy to achieve (actually beat considerably) from an air cooled 125 2T with open carb size... And given that it has been well proven that the 24 carb "restriction" is moot, There is no reason why it can't be pushed further, and from a lower rpm ceiling, and perhaps building a long fat peak power curve to say..... 11,500rpm.

[wobbly]

I dont get it at all.
Its been well proven and done for years with 125 engines - they are race reliable spinning to 14,000 all day.
Air cooled is irrelevant, old engine is irrelevant, the modern flat big end cage geometry is what makes it work with a 54mm stroke.
It is EASYER to make good power at higher rpm.
Remember Hp = Tq * RPM - so instead of going to 11500, spin it to 13500 and that equals a power increase of 2000/11500 = 17% if the
elements are designed to hold up the torque at that rpm..
And the sonic wave activity is stronger at higher rpm so getting an achievable, reasonably high bmep is, again, EASYER to achieve at higher rpm.
Having a 5000 rpm wide useable powerband from 8500 to 13500 is in fact alot EASYER to build, than having to design for a much higher bmep, to achieve the same power from 6500 to 11500.
Race reliability has NOTHING to do with the power being made, and in this case, NOTHING to do with the rpm being used, as both numbers are WELL within the limits of todays technology.

[richban]

[/I]

That is quite easy to achieve (actually beat considerably) from an air cooled 125 2T with open carb size...

Really! no shit. Well who would have thought that. Can you tell me how to build a 30hp 4 stroke please. Ta.

[speedpro]

SS90 is talking about a 2T Rich, NOT a 4T.

I don't think anybody is going to make rash claims about being able to beat your achievements regarding power from a 150cc(:nya:?) 4T with the technology we're using.