ESE's works engine tuner

[dark art]

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

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

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

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


A few years ago I found prof Blair website with some good information. You might want to check the bellmouth article:

http://www.profblairandassociates.com/RET_Articles.html

[Lightbulb]

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

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

PS: Congratulations Wobbly!

You did not mention about making your own case. It would really benefit from having an extra set of bolt hold down holes by the rear bearing, so making it a 6 hold down design engine.
Thanks for the picture. I know the work of making bar stock engines.
Neil

[F5 Dave]

Thanks for the NSR fi info and congats on the job Wob.

[FastFred]

The crankcase... 322173

CNC'd crankcase, very impressive, I like your work.

[oldjohnno]

This connection pipe, together with the cylinder and pipe volumes forms a Helmholtz system; its length and diameters determine the frequency of this system.
The header length is rather fixed by the desired wave actions, so the header diameters must have a certain value in order to arrive at the desired frequency.

Please excuse me for dredging up an old post, but this is something that has puzzled me for a while.

I'd noticed that there doesn't seem to be a close correlation between cylinder volume and pipe belly diameter - a serious 125 has a diameter of maybe 120 or so, a 250 is usually not much bigger and even 400s are still much the same. I would have thought that as the cylinder (and port) diameter increased the big end of the diffuser would would have to be proportionally bigger in order to maintain the taper angles and pressure wave establishment?

I guess some of the discrepancy would be purely because of the state of tune, but even so there are some big snowmobile cylinders with fairly high BMEP. Does a massive belly lower the Hemholtz frequency too much, and if so, does this factor trump maintaining the diffuser angles?

I just don't see a lot of big cylinders using 150 or 175mm centre sections...

[husaberg]

Please excuse me for dredging up an old post, but this is something that has puzzled me for a while.

I'd noticed that there doesn't seem to be a close correlation between cylinder volume and pipe belly diameter - a serious 125 has a diameter of maybe 120 or so, a 250 is usually not much bigger and even 400s are still much the same. I would have thought that as the cylinder (and port) diameter increased the big end of the diffuser would would have to be proportionally bigger in order to maintain the taper angles and pressure wave establishment?

I guess some of the discrepancy would be purely because of the state of tune, but even so there are some big snowmobile cylinders with fairly high BMEP. Does a massive belly lower the Hemholtz frequency too much, and if so, does this factor trump maintaining the diffuser angles?

I just don't see a lot of big cylinders using 150 or 175mm centre sections...

You might find, most bikes can't accommodate those fat bellied pipes.

[Frits Overmars]

I'd noticed that there doesn't seem to be a close correlation between cylinder volume and pipe belly diameter - a serious 125 has a diameter of maybe 120 or so, a 250 is usually not much bigger and even 400s are still much the same. I would have thought that as the cylinder (and port) diameter increased the big end of the diffuser would would have to be proportionally bigger in order to maintain the taper angles and pressure wave establishment?The belly diameter of a serious 125 cc is more like 130 mm, and bigger cylinder volumes should have proportional bigger bellies; you can find the relation in the concept drawing below. But when did you last see a serious (that is: tuned for power) 250 or even 400 cc engine? Most big singles are MX machines and their power out of the box is already too much for the average rider. Besides, as Husa said, you wouldn't be able to fit a real effective pipe on such a machine.


I guess some of the discrepancy would be purely because of the state of tune, but even so there are some big snowmobile cylinders with fairly high BMEP. Does a massive belly lower the Hemholtz frequency too much, and if so, does this factor trump maintaining the diffuser angles?The best snowmobile engines hardly reach 2/3 the BMEP of a 125 GP engine. That's understandable because they are utilitarian products. If you want to extract more power from them, you'll need to fit bigger pipes.
A massive belly or rather a big pipe volume does lower the Helmholtz frequency but then the bigger header diameter raises it (and the bigger header length lowers it again). It's only right because at the same specific time areas for blowdown and transfer, a bigger engine needs a lower resonance rpm and corresponding frequency.
322322

[oldjohnno]

Thanks for the replies.

I have to say though that in my little world even 2/3rds of 125 GP BMEP is pretty high ;)

[ken seeber]

Johnno, in our Oz, there is a speedway class called microsprints, where they run 250 ccc engines. Tons of space, so you can fit any sized pipe that your heart desires.
322227

[Greg85]

hello,
i am new to the forum,this is very good forum for two stroke!
i am interseted in a lot of karting engine ,now i am interested in working with the cylinder jaros bench is anyone really knows this system for well optimized
cylinderworked in what sense?
THANK YOUimg_3533.jpgimg_3535.jpgimg_3536.jpg

[Greg85]

[QUOTE=Greg85;1130977145]hello,
i am new to the forum,this is very good forum for two stroke!
i am interseted in a lot of karting engine ,now i am interested in working with the cylinder jaros bench is anyone really knows this system for well optimized
cylinderworked in what sense?
THANK YOU http://imageshack.com/a/img921/937/VVRVTt.jpg

[peewee]

guys I have a new crankcases and all the surfaces are rough and bumpy from the casting. is there any reason not to smooth down all these surfaces ? atleast so maybe a crack doesn't form in the future

[wobbly]

The belly diameter as far as I can see has no relationship to the engine displacement.
Its all down to effective energy recovery within the pipe,and as the energy is finite you can decide where that energy is used.
As Frits says, the latest really fast 125 engines are a bit over 130mm, and use steep tapers to extract the maximum ( optimum ) depression
and reflection pressure ratios at the Ex port.
The bmep sets the available energy, and as you go up in displacement it becomes harder and harder to get anything like the bmep numbers of the square 125.
If you tune a MX250 to the highest possible level for road racing, then the long stroke limits what can be achieved and I found that when going thru the exercise
of developing a pipe for this class that a belly over around 140 ( with steeper angles ) makes no more power.
The square bore/stroke Gas Gas for example can go a somewhat harder, but it then topped out at about 145mm.

Re the Jante CNC driven scavenging vector visualizing machines.
These use a small tube with several pitot sensors linked to a computer that shows the velocity and the direction of transfer flow.
They take a huge amount of time and experiment to determine what the effect of these vectors have on scavenging.
But when finally understood, the Yamaha chief engineer that developed the cylinders for the 500GP machines that went on in 2000 to win the 250GP class, said to me it took him 3 years but he was now
able to predict the power curve with his Jante,without needing to use the dyno for confirmation.
Bartol had one for years but I dont think he ever really got a handle on what he was seeing on the screen, as most of his later work I have seen was basically a copy of Honda technology.
But the Roberts guys had one at Bud Asklands workshop, and he really knew what needed changing,and this helped Rainey and Yamaha immensely when Kenny was allowed to overule
the factory engineers with his own work.

[Frits Overmars]

i am interested in working with the cylinder jaros bench is anyone really knows this system for well optimized cylinderworked in what sense?Here you go, Greg.322241

[oldjohnno]

The belly diameter as far as I can see has no relationship to the engine displacement.
Its all down to effective energy recovery within the pipe,and as the energy is finite you can decide where that energy is used.
As Frits says, the latest really fast 125 engines are a bit over 130mm, and use steep tapers to extract the maximum ( optimum ) depression
and reflection pressure ratios at the Ex port.
The bmep sets the available energy, and as you go up in displacement it becomes harder and harder to get anything like the bmep numbers of the square 125.
If you tune a MX250 to the highest possible level for road racing, then the long stroke limits what can be achieved and I found that when going thru the exercise
of developing a pipe for this class that a belly over around 140 ( with steeper angles ) makes no more power.
The square bore/stroke Gas Gas for example can go a somewhat harder, but it then topped out at about 145mm.



Thanks Wob. It seems that once the cylinder gets bigger a whole lot of practical considerations come into play. Accommodating a huge pipe on the bike is one, then there are the rpm limits set by piston speed and vibration levels. On top of this is the fact that the big single will most likely have only 5 gear ratios and I guess it takes longer to fully burn the contents of an 80mm diameter chamber than a 52mm one. There's less cooling surface area and the big pots seem more prone to knocking. Something else I've come across is the lack of cylinder wall area in which to cut holes - as the cylinder is made bigger (and especially if it's oversquare) the wall area to cylinder volume ratio decreases. Try as you might, you can't cut a hole in a hole...

[TZ350]

Spent an enjoyable day playing with the dyno and EFI system.

I took the time to carefully check the actual timing of the injection end point. I did it in much the same way you would check the ignition timing with a strobe light and found that where the software said it is and where it actually is, is pretty much spot on.

After a lot of careful work starting just before the transfers open and making 5 deg incremental adjustments until just after the transfers close. I found the best spot for my engine was to finish the injection cycle at 200 deg before TDC.

The Ectrons EFI system measures everything in deg BTDC, so my transfers open 245 deg BTDC and close 65 deg BTDC and by experiment the best injection end point is 200 deg BTDC, so a lot of the injection cycle into the transfers is happening before the transfers actually open.

322261

Now that I have confirmed that the injection end point sweet spot is around 200 deg BTDC. The mass flow simulations make more sense. When you look at the Engmod2T simulation for my bike, of mass flow through the transfers. They all peak at about 200 deg BTDC. Or just before BBDC, and around BDC is where Wob says the pipe should be sucking the hardest.

The Ecotrons EFI software has an injection end map that allows for fine tuning of the injection end point over a range of RPM and Engine Load. So a bit of fine tuning to do but for now I am confident that we are in the ballpark. And that if the software says 200 deg BTDC then that is pretty much what it is, I was never sure before.

[jfn2]

Hello Frits;
I was not able to see the exhaust concept drawing you posted yesterday. I usually don't have any trouble. Would you please repost the pic? Thank you very much. Jeff

[Frits Overmars]

No problem Jeff. But if I do the same thing twice, chances are that so will your computer.
Maybe the picture format plays a role. The png-format that I use, doesn't normally give any problems but just in case here are a png- and a gif-format.322324 322323

[Martin1981]

Wobbly, i have a Question regarding the 04 CR Cylinder you talked about not long ago.

I have one but I can not see the reverse Transferport Stagger. Is it only a couple of Tenths of a mm so one can`t see it? Also it has very high Transferports, about 15mm.

I know that there are 2 Types of Cylinders. Cylinder A 12110-KSR-A00 and Cylinder B 12120-KSR-A00.

So is it possible that Cylinder A does not have the Stagger and Cylinder B has it? Or are there other Differences between the Cylinders?

Thanks!

[jfn2]

Thank you very much Frits. The gif format worked but the png format did not. I am using windows 10.

[wobbly]

Here is the cylinder I have sitting on NSR20 MC21 cases.
The reverse stagger is obvious, I will check what casting this came from.

[Martin1981]

Yes indeed, more than 1mm Difference in Port height is obvious. But on my cylinder all Transfer Ports have the Same height (42,2) May be someone ground them. I have to Check.

[Greg85]

Here you go, Greg.322241

Thanks you Mr frits !!:niceone: this very good documentation !

[Martin1981]

http://www.fotos-hochladen.net/thumbnail/20160613155945vnps167ye3_thumb.jpg (http://www.fotos-hochladen.net/view/20160613155945vnps167ye3.jpg)


http://www.fotos-hochladen.net/thumbnail/20160613155833bohgy8rv26_thumb.jpg (http://www.fotos-hochladen.net/view/20160613155833bohgy8rv26.jpg)



http://www.fotos-hochladen.net/thumbnail/cru6cq89awjl_thumb.jpg (http://www.fotos-hochladen.net/view/cru6cq89awjl.jpg)


The first 2 pics show my Cylinder. No Stagger and as you can see nothing has been ground.

Wobbly, thanks for the drawing you posted but there must be something wrong. It says that At BDC piston is approx 0.0mm above bottom of transfer ports. With 54,5mm Stroke and 15mm high Transferports (B and C) the engine can not have 131,62° transferduration.

With 54,5mm Stroke and let us say a 110mm long rod, piston at BDC approx 0.0mm above bottom of transfer ports the Cylinder has to have about 13,3mm high b ports to have 131,62° Transferduration. But the ports are 15(!)mm high. And that makes 140° Transferduration.

[jonny quest]

The cr125 rods are 104mm

[seattle smitty]

That's funny, Jeff. That attachment of Frits' (post #23014) is about the first attachment of his that I ever have gotten to open and read (but I readily admit to being computer-stupid).

[Martin1981]

The cr125 rods are 104mm

Ok. Thanks Jonny!

[Bert]

Spent an enjoyable day playing with the dyno and EFI system.

I took the time to carefully check the actual timing of the injection end point. I did it in much the same way you would check the ignition timing with a strobe light and found that where the software said it is and where it actually is, is pretty much spot on.

After a lot of careful work starting just before the transfers open and making 5 deg incremental adjustments until just after the transfers close. I found the best spot for my engine was to finish the injection cycle at 200 deg before TDC.

The Ectrons EFI system measures everything in deg BTDC, so my transfers open 245 deg BTDC and close 65 deg BTDC and by experiment the best injection end point is 200 deg BTDC, so a lot of the injection cycle into the transfers is happening before the transfers actually open.

322261

Now that I have confirmed that the injection end point sweet spot is around 200 deg BTDC. The mass flow simulations make more sense. When you look at the Engmod2T simulation for my bike, of mass flow through the transfers. They all peak at about 200 deg BTDC. Or just before BBDC, and around BDC is where Wob says the pipe should be sucking the hardest.

The Ecotrons EFI software has an injection end map that allows for fine tuning of the injection end point over a range of RPM and Engine Load. So a bit of fine tuning to do but for now I am confident that we are in the ballpark. And that if the software says 200 deg BTDC then that is pretty much what it is, I was never sure before.

Really interesting watching/reading you getting on top of this.
Keep the updates coming.
I had noted that ecotrons did a twin unit for a Ninja250 and have been following this thread with interest for the TZR250 project.:msn-wink:

[wobbly]

Yes Martin, something is wrong - I have a second hand cylinder that was measured, and now I have a new one as well.
The new one has no stagger I can see - the second hand one has the big stagger, so im not sure what is going on yet.

[speedpro]

Really interesting watching/reading you getting on top of this.
Keep the updates coming.
I had noted that ecotrons did a twin unit for a Ninja250 and have been following this thread with interest for the TZR250 project.:msn-wink:

The Ninja kit is what I have running on my FZR twin. Plugged straight in.

[Martin1981]

I have a second hand cylinder that was measured

Does it have the Stagger "cast in" from the Factory or is it ground in afterwards by someone?

Edit:just thought about it....the stagger can not be ground in afterwards. the no stagger cylinder has the 42,2mm distance from top of the c and b port to the top of the cylinder and the stagger cylinder also. so someone must have "lowered" (epoxied) the a ports roof to achieve the stagger but i think that is not the case.

[jfn2]

Wobbly
I looks like you got a RS 125 cylinder and not a CR 125 cylinder.

[Martin1981]

Wobbly
I looks like you got a RS 125 cylinder and not a CR 125 cylinder.


How can you know? might be an explanation but i think Wobbly is able to distinguish an rs and a cr cylinder.

[wobbly]

I can tell you with absolute assurance that Honda NEVER made an RS125 cylinder with reverse stagger like an Aprilia.
And the 04 CR125 was the ONLY model with a cable operated PV, that is why I got one to test fit on a NSR250 MC21.

[Sketchy_Racer]

So I have a question for the gurus of two strokes.

I have recently made some pretty big changes to my engine (NSR300) and as such have had a significant increase in power, spread and over-rev. These are all fantastic things that make me happy. In this change I have observed a lot stronger signal at the carburetor which has required me to reduce my Jet size considerably despite making more power.

Why is it that as the air velocity through a carb changes the fuel flowing through through the venturi is not proportional to this velocity change?

Cheers,
Sketchy

[wobbly]

Simple, the changes you have made will have contributed to making 1 or more of the 3 main variables, rise in value.
That is Trapping Efficiency,Scavenging Efficiency and or Delivery Ratio.
What accompanies an increase in 1 or more of these, is usually that you change the Brake Specific Fuel Consumption number ie Lbs/Hp/Hr - Kg/Kw/Sec
and thus make the engine more efficient at using the injested fuels energy to make power.
The bottom line, where say making the stinger bigger is a perfect example, is you have reduced the fueling needed to keep the engine alive ie using fuel to cool
the engine and prevent deto or seizure, and using it instead to make Hp.
Thus dropping the BSFC, means a leaner jet will make more power , safely - its a myth that more power automatically needs more fuel.
In fact depending upon the mods done, the carb velocity may well have DROPPED, but the air ingested is being used more efficiently to produce Hp.
And finally all of the above effects are easily seen and graphed in EngMod - not " just " the final effect of more Hp.

[jonny quest]

Does the NSR300 use the NSR150 cylinders?

I just received my MC21 here in the USA. I haven't looked at all my options yet, but I'm either going to do a +2mm over bore on stock cylinders using 00 RM125 pistons, or graft CR125 cylinders on mine. I have 2 05-07 CR125 cylinders already.

Wob, you are correct, 04 was the only year for the servo operated PV on CR.

[TZ350]

322357

My latest adventure with the EFI is to adapt a Dellorto TPS to my favorite 24mm OKO carb.

Then the OKO can be run as an EFI throttle body or Carb for back to back tests.

I also plan to fit a wide band Lambda sensor and EGT and CHT gauges to keep track of things.


322358

Wouldn't you know it, dam carb won't fit now!!!!!!! Ok now I have to cut some of the clutch cover away.

322362

One of the EFI problems I hope to solve by comparing back to back EFI runs to the carb is this funny issue where on less than 20% throttle the EFI engine goes through cyclical patches as it is accelerating. Patches of running smooth and then rough then smooth again. The rough patches have a peak in the middle and diminish in amplitude overall as the rpm increases.

It is obviously a resonance thing, but what is resonating? Pipe? Transfers/Case Volume? Pipe/Case Volume???? Inlet ..... :scratch:

322363

My current EFI issues are all about trying to get it running nicely at less than 20% throttle. Although you can see cyclical humps it looked like I was getting onto the money Ok when I got this <20% TP dyno run.

322364

But I realized later that the nice graph was done in first gear and the spiky one is top gear. So under real load its still a bag of poo.

[TZ350]

The mid chamber bleed re visited .....
The mid chamber bleed re visited as it might be useful for some low end boost......
Ok the mid pipe bleed didn't work for me as a detonation suppressant but it did show a useful low end boost. The interesting thing was that there was very little noise from it.

286902

Red line is the bleed in the open position, Blue is closed.

286903286904

And there was those who scorned me for trying this ....... :D
I will re visit this again, maybe with a bleed system like Frits suggested.

Twotempi has suggested to me to try a different diameter muffler, different pipe and possibly re visit the pipe bleed experiments I did a while back, to see if its really a resonance issue and if some simple changes could help.

[jonny quest]

TZ350, you may have just solved your issues, and created a ton more work for yourself.

Sounds like you need to incorporate a gear position apparatus, and incorporate different maps for each gear

[jonny quest]

TZ, regarding your center section bleed. I found similar results on a test pipe.

I always wanted to build a one way reed valve. The performance gain could possibly be outside air cooling down pipe gasses.

[wobbly]

The bottom line is that a pipe bleed will always make much more bottom end and less top.
This is one reason why Jetski's make so much bottom end power,using a big stinger, thus reducing the pipes effectiveness by dropping the low rpm retained
back pressure, as this effect cranks up the bottom end.
Then as the engine comes onto the pipe, they squirt water into the stinger, effectively reducing the exit discharge coefficient and pumping up the top end power.
A variable exit stinger Cd will be a great way to optimize power , no matter how its done.
But sadly it has no effect on the injection issue TZ is struggling with - I wish I could help , but no free lunch yet - sorry.

[husaberg]

TZ, regarding your center section bleed. I found similar results on a test pipe.

I always wanted to build a one way reed valve. The performance gain could possibly be outside air cooling down pipe gasses.


https://www.youtube.com/watch?v=hQTPNdOuzwE
https://www.youtube.com/watch?v=jEnNMTMZadw

[Ocean1]

Bruce's youchoob stuff

Probably safe, as long as it don't have wings...

https://en.wikipedia.org/wiki/Bruce_Simpson_(blogger)

[husaberg]

Probably safe, as long as it don't have wings...

https://en.wikipedia.org/wiki/Bruce_Simpson_(blogger)

I heard the cruise missile is tucked away somewhere near Ahaura:msn-wink:

[Flettner]

[QUOTE=husaberg;1130978502][video=youtube;hQTPNdOuzwE]https://www.youtube.com/watch?v=hQTPNdOuzwE[/video/QUOTE]

Is that not the Ryger, just add a piston and cylinder in there and you have it!

[jamathi]

Yes, the idea is to make the piston skirt 'water ski' over the oil film instead of scraping the oil off. You don't really need a radius there, a 5° chamfer will do fine.

Corrected that for you Wob.

The main problem with Derbi and Aprilia RSA steering was the fairing.
It was made by Porsche.
At high speeds there was too much directional stability due to the fairing.
It was difficult to incline into a fast corner.
Fitting an Aprilia RSW fairing resolved this problem.

[husaberg]

The main problem with Derbi and Aprilia RSA steering was the fairing.
It was made by Porsche.
At high speeds there was too much directional stability due to the fairing.
It was difficult to incline into a fast corner.
Fitting an Aprilia RSW fairing resolved this problem.

Welcome Jan we all hope to hear plenty more from you.
http://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=310217&d=1427265013
http://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=277987&d=1360050257

[jamathi]

That is great news Wob :niceone:. You'll be just 1400 km away then instead of 19000 km. Hope to meet you there.

So my friend Franco listened to me, I am happy to hear that!
I told him that in my opinion you are the best tuner in the world.
Pesaro is a very nice place to be, I worked there for 1 year.
Hope you'll enjoy it!!
And you will love the food.

[jamathi]

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

The Ryger guys certainly need some help.
Their engine doesn't last for more than half an hour.
And there also seems to be not much power....

[jamathi]

The belly diameter as far as I can see has no relationship to the engine displacement.
Its all down to effective energy recovery within the pipe,and as the energy is finite you can decide where that energy is used.
As Frits says, the latest really fast 125 engines are a bit over 130mm, and use steep tapers to extract the maximum ( optimum ) depression
and reflection pressure ratios at the Ex port.
The bmep sets the available energy, and as you go up in displacement it becomes harder and harder to get anything like the bmep numbers of the square 125.
If you tune a MX250 to the highest possible level for road racing, then the long stroke limits what can be achieved and I found that when going thru the exercise
of developing a pipe for this class that a belly over around 140 ( with steeper angles ) makes no more power.
The square bore/stroke Gas Gas for example can go a somewhat harder, but it then topped out at about 145mm.

Re the Jante CNC driven scavenging vector visualizing machines.
These use a small tube with several pitot sensors linked to a computer that shows the velocity and the direction of transfer flow.
They take a huge amount of time and experiment to determine what the effect of these vectors have on scavenging.
But when finally understood, the Yamaha chief engineer that developed the cylinders for the 500GP machines that went on in 2000 to win the 250GP class, said to me it took him 3 years but he was now
able to predict the power curve with his Jante,without needing to use the dyno for confirmation.
Bartol had one for years but I dont think he ever really got a handle on what he was seeing on the screen, as most of his later work I have seen was basically a copy of Honda technology.
But the Roberts guys had one at Bud Asklands workshop, and he really knew what needed changing,and this helped Rainey and Yamaha immensely when Kenny was allowed to overule
the factory engineers with his own work.

As far as I know Yamaha just copied the Honda cylinders to win the 2000 250 championship
Later they even produced an SAE paper about this....
Fitting a Honda cylinder on a Yamaha engine was first done by my old friend Cees van Dongen
On his son's 125 Yamaha.
Later he sold the casting models to Bartol, who then became a Yamaha consultant....

We had such a Jaros machine at Aprilia, it proved to be useless.
Above all the results were not repeatable.
DEA engineering made a far better version of it himself.
I don't know anything about it's results.

[Flettner]

The Ryger guys certainly need some help.
Their engine doesn't last for more than half an hour.
And there also seems to be not much power....

So where did their claim of 70HP come from? And the 30,000 RPM, that had us guessing for a long time. Perhaps someone in the team opened their mouth too early? Disappointing to see it all come to nothing in the end, never the less it was a good guessing game:clap:

[jamathi]

So where did their claim of 70HP come from? And the 30,000 RPM, that had us guessing for a long time. Perhaps someone in the team opened their mouth too early? Disappointing to see it all come to nothing in the end, never the less it was a good guessing game:clap:

Just bluffing.
70 HP was never measured on a dyno.
I still wonder how many people could believe this, without seeing a power curve
Probably it was calculated, using Mota.
And of course talking about 30.000 revs has always been ridiculous...
The main problem seems to come from the nikasil plated piston.
The far too short connecting rod surely will not help.
Just imagine the friction between the small diameter part (46MM) of the piston an the separator plate with such
a very much inclined connecting rod at maximum piston speed....
Impossible!

[husaberg]

Here is the cylinder I have sitting on NSR20 MC21 cases.
The reverse stagger is obvious, I will check what casting this came from.

Wob I found this
You had a bit to do with some of his stuff earlier on.

http://nsr250.freeforums.org/tuckerbag-s-2004-nsr250-using-2004-cr125-barrels-t414-20.html

have definitely made an error with the different height of the A port in relation to the B and C ports.
In reality they seem to be identical, height-wise. This throws doubt on the whole picture.
I need to do a total re-measure. Well spotted and thanks for pointing it out.

I do NOT know what I was thinking to get it so wrong. D'oh!
Maybe I just had the Aprilia "reverse stagger" on my mind, and added in a bit of wishful thinking?? ;)
In reality I probably just mis-read 42.1 as 43.1 or something completely stupid like that.

Hopefully I can re-measure this weekend and get a corrected port map put up.

[tjbw]

Welcome Jan we all hope to hear plenty more from you.


Seconded!

Welcome Jan.

I was just thinking the other day, about the remarkable quality of information shared here on KB, by wobbly, Frits, flettner, Ken, husa and many others. Now Jan is contributing too, that's the best news.

[trevor amos]

Jan Thiel posting on the Bucket site, it`s true then, Christmas does come twice a year! Terrific to have you here Jan, welcome.

Trevor

[Frits Overmars]

322412
. .

[Martin1981]

Wob I found this
You had a bit to do with some of his stuff earlier on.

http://nsr250.freeforums.org/tuckerbag-s-2004-nsr250-using-2004-cr125-barrels-t414-20.html


Hi Husa, i asked Tuckerbag the Questions about the Cylinder. In the drawing there IS a mistake, yes. So as i understand it Tuckerbag does NOT have a staggered cylinder. But wobbly HAS a staggered one. so i am excited and looking forward to what wobbly will find out about it. maybe one of only few existing staggered cylinder made by honda for what reason?


I am also very happy about Jan posting here now!

[Sketchy_Racer]

Well the last few months for me have been a great learning exercise. I've made pretty big changes to my NSR300 motor and found some good things along the way.

The first change I started experimenting with was the chambers. I went about modeling a FOS pipe in engmod and then tweaked dimensions from there. The biggest change that the engine so desperately needed was a increase in the nozzle diameter. As it would turn out all the trouble that I've had with detonation and having to run very very large jets to compensate was mainly due to this. As soon as the stinger was increased detonation in the simulation went away. So I've now gone from a 21mm nozzle to a 24.5mm nozzle. Massive change.

Next was the chamber itself. They Tyga chamber isn't too far off what I needed so with a cut of 40mm off the header and added 40mm into the belly it was in the ball park. This is still not the optimum and engmod suggests that there is still 4-5hp hiding in the chambers themselves, this is a work in progress.

Finally came the changes to the exhaust port. The NSR150 barrels come with parrallel exhaust duct walls. Again as suggest by engmod and researching on this fantastic thread I found there was to be much gained from porting into the side wall to get a larger flow area on the Ex port. As it seems to be the NSR150 barrels have enough transfer time/area but lack blowdown.

322423

322424

Finally when building the new motor I decided to also try using a radius on the edge of the piston, mainly for lubrication properties but also in hope that I may gain some flow when the ports are partially open.

322425

The end result is this:

322422

The change in engine characteristic is significant and on track the additional spread of power has transformed how I can ride the bike.

There is still a small dip in the power curve that I haven't had a chance to iron out yet. I believe this is just incorrect power valve timing

The only problem that I have now is that the motor revs too high and I'm worried about crank life. Does anyone have any good ideas on how to bring the power down the rpm range?

[jamathi]

Well the last few months for me have been a great learning exercise. I've made pretty big changes to my NSR300 motor and found some good things along the way.

The first change I started experimenting with was the chambers. I went about modeling a FOS pipe in engmod and then tweaked dimensions from there. The biggest change that the engine so desperately needed was a increase in the nozzle diameter. As it would turn out all the trouble that I've had with detonation and having to run very very large jets to compensate was mainly due to this. As soon as the stinger was increased detonation in the simulation went away. So I've now gone from a 21mm nozzle to a 24.5mm nozzle. Massive change.

Next was the chamber itself. They Tyga chamber isn't too far off what I needed so with a cut of 40mm off the header and added 40mm into the belly it was in the ball park. This is still not the optimum and engmod suggests that there is still 4-5hp hiding in the chambers themselves, this is a work in progress.

Finally came the changes to the exhaust port. The NSR150 barrels come with parrallel exhaust duct walls. Again as suggest by engmod and researching on this fantastic thread I found there was to be much gained from porting into the side wall to get a larger flow area on the Ex port. As it seems to be the NSR150 barrels have enough transfer time/area but lack blowdown.

322423

322424

Finally when building the new motor I decided to also try using a radius on the edge of the piston, mainly for lubrication properties but also in hope that I may gain some flow when the ports are partially open.

322425

The end result is this:

322422

The change in engine characteristic is significant and on track the additional spread of power has transformed how I can ride the bike.

There is still a small dip in the power curve that I haven't had a chance to iron out yet. I believe this is just incorrect power valve timing

The only problem that I have now is that the motor revs too high and I'm worried about crank life. Does anyone have any good ideas on how to bring the power down the rpm range?

Just make your pipe a little bit longer in small steps, maybe 5mm is enough. At the flange, or the beginning of the header.
21mm was surely too small!
You can use distance pieces between flange and header for quick tests.
I did this on my 50cc from 1969 with very good results

[Sketchy_Racer]

Just make your pipe a little bit longer in small steps, maybe 5mm is enough. At the flange, or the beginning of the header.
21mm was surely too small!
You can use distance pieces between flange and header for quick tests.
I did this on my 50cc from 1969 with very good results

Thank you Jan, I will experiment with this next time I am on the dyno.

[jonny quest]

Pipe length is easiest to try like Jan said.

The radius on the Pistons probably did the most damage to your powerband. That may have not been the best direction

[ief]

You're looking at the wrong one Jonny, he only wants to get rid of the flatter area before peak power.

[wobbly]

Yes, 21mm is WAY too small even for the 250 engine..
And looking at the PV,it wont be working hardly at all with that big space down each side.
You need to add weld to the PV blade side walls and grind pockets further up in the duct to get alot better sealing.
Also looking at the dyno curve the overev thru the gears would be all done at 12500 - that isnt reving hard at all.
From memory the Tyga pipes have way steep rear cones, that wont be helping the dramatic drop off in power past peak.
So I would be getting the header and diffuser length % correct,then lengthen the rear cone to gain some upper mid,without loosing
any overev.
The rear cone is easy enough to replace as a single section.
The other big issue with the 150 cylinders is that they have no port stagger,and the roof angles are very flat.
Fix that and you will pump up power everywhere.

[ken seeber]

322412
. .

Jan, welcome. This makes it a Triple Whammy for ESE. The key thing is to keep these guys stimulated.

[TZ350]

So my friend Franco listened to me, I am happy to hear that!
I told him that in my opinion you are the best tuner in the world. Pesaro is a very nice place to be, I worked there for 1 year.
Hope you'll enjoy it!! And you will love the food.

Great to have Jan here and to hear his endorsement of Wobbly.

[JdG]

Jan Thiel calling you the best tuner in the world... That should shut up those who criticize Wobbly for a while...:2thumbsup

[wobbly]

"That should shut up those who criticize Wobbly for a while"

Na wont happen, as I said at the time those smartarse flamers didnt criticize with any intelligent logic to justify their opinions,
they think personal attacks are clever and much more insightful, yea right.

I will just carry on helping out by detailing here what I think is the reality's of tuning 2Ts, and no matter what they may think or say - who got the
job at one of the best companies in the world actually building Championship winning engines.

Thanks Jan , I appreciate the kind words and all your help with my personal " education ".

[WilDun]

"That should shut up those who criticize Wobbly for a while"
Na wont happen, as I said at the time those smartarse flamers didnt criticize with any intelligent logic to justify their opinions.

Just let it all ride over your head Wobbly, everyone is entitled to their opinion, but history will eventually sort out whether they are right or wrong, meantime your "Wobbly Wisdom" is greatly appreciated and used by many here, (if not most), but you have a task ahead of you and you need to keep focused on that.
I don't have a lot of input on this thread, but from what I have seen, you are a great contributor.
Congratulations and good luck with the new job.

[sispeed]

Hello. I know there are at least to Posts stating that a motor with a leak in the case, Gasket or Seal, is running rich.
Unfortunately I can confirm that this is true. Had the Problem on my last race event on the German Sachsenring.
And like stated from Wobbly it sized as I went leaner on the main to correct. The surviving side was dark black. So all statements are proved an it was a sad day for me.
Since then I tried to get my head around why the the motor runs rich and what exactly forces the rich condition.
Can someone give an explanation on the effect? That would be great.
Thank you
Regards Siggi

[husaberg]

Hello. I know there are at least to Posts stating that a motor with a leak in the case, Gasket or Seal, is running rich.
Unfortunately I can confirm that this is true. Had the Problem on my last race event on the German Sachsenring.
And like stated from Wobbly it sized as I went leaner on the main to correct. The surviving side was dark black. So all statements are proved an it was a sad day for me.
Since then I tried to get my head around why the the motor runs rich and what exactly forces the rich condition.
Can someone give an explanation on the effect? That would be great.
Thank you
Regards Siggi

TeeZee some pumper carb tuning tips to go with Wobblys info. 247635

And here is something if we really cock it up..... :laugh: ...... piston seizures explained 247636

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.



I could have got this wrong but when he says air leak could he have been referring to a manifold air leak and if it does will this still cause it to run rich as in your analogy Wob?.
I am not challenging you. Just curious? because I always was lead to believe a manifold air leak runs lean and it always seem to on four strokes.

Piston specs here inc ring peg locations
http://www.pvlsverige.se/vrm/kolvar/kolvar.html

Also below a very old way of securing circlips. Which I think its quite cool. Clever bugger that Phil Irving

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.

I think this is what you are looking for.

[Frits Overmars]

Had the Problem on my last race event on the German Sachsenring.... Regards SiggiSiggi? Siggi who?
Not this Siggi by any chance? Too bad I couldn't make it to the Sachsenring this time, mate.
322507

[breezy]

I think this is what you are looking for.

wobbly, would there be any benefits if you could control the air leaked/added into the crankcase with this richening phenomenon.

[wobbly]

There have been plenty of attempts at " cheating " the rules and allow extra air into the engine when the carb is a spec size, and these do work as
long as you can then retune the A/F ratio correctly.
But the issue with a case leak is that it affects badly the delivery ratio.
With a leak there is less air flow into the case as any pipe effect that pulls down the volume below atmospheric is diluted, and then the small
effect the case compression has on transferring mixture into the cylinder is also reduced.
As I said the engines ability to act as a "pump " is seriously affected,and I cant see any method of harnessing this to any useful end.

[peewee]

I think this is what you are looking for.

would it not be like a straw in a bottle of soda. poke a hole in the straw above the soda and try to suck. seems like you have more air and less soda going up the straw. what am I missing ?

[sispeed]

Thank you for the answers and hints. This is really a great forum with very nice friendly people, willing to give their experience to others.
The no longer effective pumping was what I also thought but could not get it clear in my head.
@Frits: No, not me. I race in the "Klassik Tropy" and not really the fastest rider ;-)
Sachsenring was a great event and an absolute Highlight was the World GP with all the great riders and a lot of 500 2-strokes http://www.worldgpbikelegends.com/
and the best thing they were not parading they were racing, even Jim Redmann with his 84 Years was not slow.
I would be very happy if I could manage to climb on a motorcycle that old.
I don't know if you can see this page without a FB account, but I hope
https://www.facebook.com/SchrauberbudeRacing
Not so up-to-date
http://schrauberbude.de/motorrad/racing.html
and nearly everything only in german
Thank you for your replies and information
Regards Siggi

[ken seeber]

Memory test for you oldies or know-it-alls. I have a question about the very first Yamaha 250 cc race bikes that came out, the TD1A.
Were the cylinder bores hard anodised or (as another memory flash I had), coated with “channel cracked chrome?”
If it was hard anodised, does anyone have any recollection if it was any good or had any problems?
Also, while you are thinking, has anyone had any experience with the Kawasaki WESC (wire explosion spray coating) bores. Was certainly used on some KX125 cylinders.

[TZ350]

322570

Got the carb and TPS sorted, now I can easily change between Carb or EFI simply by switching the fuel between the carb or EFI fuel pump.

322573322569

Currently the slow speed fuel injectors fire across the bottom of the transfers (illustration A) I am beginning to think that the timing of the squirt to get the narrow band of air/fuel mixture into the cylinder is too difficult and maybe the source of my problems.

322572322576

I might have better luck by squirting the fuel vertically down the transfer (illustration B) that way a greater area of the transfer volume has a good air/fuel mix in it making the delivery timing less critical. The very successful EFI YZ250 that Flettner worked on had the injectors firing vertically down the transfers. But positing the injectors this way on an air cooled cylinder is hard to do because the fins get in the way, especially the head fins.

322571

Firing through the transfer port window and across the cylinder into the face of the oncoming transfer air stream from the other side may be an even better yet (illustration C). I think this is similar to what Flettner is thinking of doing on his new engine. And it might be the most physically easy way to position the injectors on my air cooled cylinder. It would directly cool the piston crown too.

[husaberg]

Memory test for you oldies or know-it-alls. I have a question about the very first Yamaha 250 cc race bikes that came out, the TD1A.
Were the cylinder bores hard anodised or (as another memory flash I had), coated with “channel cracked chrome?”
If it was hard anodised, does anyone have any recollection if it was any good or had any problems?
Also, while you are thinking, has anyone had any experience with the Kawasaki WESC (wire explosion spray coating) bores. Was certainly used on some KX125 cylinders.

No idea but it would be in the Yamaha twins book which I have but I have no idea where it is.
The info on the TD1A is pretty sketchy at best with even very few pictures of the bike.
One thing I do know is it did have std exhausts that looked for all the world to be off a Triumph twin of the period.
Big brakes that were later used for the B and C
I think the method about the same period of the TD1A was hard chromed iron liners then etched to retain oil, but I have no idea for sure. What it had std.
Edit classic bike or classic racer has about a 5 page spread on them (in about 1992-95ish)

okay google

With this fitment, the YDS1R was now a 30 hp, 100 mph road racer. It was though, unreliable and too heavy to be a winner in the western world of motorcycle racing. The first Alloy barrels had chrome linings, which at the time were by no means perfect. The plating would lift off from around the ports, causing seizures. Ported iron barrels were also used on many Asama’s, before or perhaps while alloy ones were not available, or indeed to stop the seizures!


The engine of the TD1 retained the Hitachi magneto (with red HT leads) and the 27mm Mikuni 276 carburettors. Improved “low expansion” pistons were fitted and the barrels were now anodised. It was the pistons that now had to be carefully run in, as the bores were not easily re-boreable.


As the TD1A was based on the YDS2, the YDS3 lent its’ improvements to the TD1B.

The first 1B’s retained the 1A’s round orange-red fuel tank (known as the watermelon tank in the US), seat unit and general chassis. The rear shocks were improved to stiffer, adjustable units and the forks were again up-rated.

The engine was of course now based upon YDS3 crankcases, with tuned, chrome lined alloy barrels, racing heads, single ring pistons and racing crank. The bulge on the side of the crankcase, which housed the oil pump on the YDS3 was now empty, behind it was only a blanking off plate. The redundant alloy of the oil pump housing was often removed by racers, trying to save that extra bit of weight.
http://www.classicyams.com/production-racers/productionracers/birth-of-the-yamaha-tds.html

for giggles
322581

[Flettner]

Memory test for you oldies or know-it-alls. I have a question about the very first Yamaha 250 cc race bikes that came out, the TD1A.
Were the cylinder bores hard anodised or (as another memory flash I had), coated with “channel cracked chrome?”
If it was hard anodised, does anyone have any recollection if it was any good or had any problems?
Also, while you are thinking, has anyone had any experience with the Kawasaki WESC (wire explosion spray coating) bores. Was certainly used on some KX125 cylinders.

First ones were indeed Hard Anodised but didn't last very well. Next was hard chrome (back etched) straight onto the aluminium bore. Using hydrafluric acid as a pre etch, nasty stuff. There was a need to run cast iron rings against these bores, so also not so usefull when the rings started to get thinner. Then finaly a nikasil type finish with the ring being hard chromed, 'the final solution' as it were.

[peewee]

i wonder if you could machine the sides of a standard piston so there was only a few ribs that contact the cylinder wall. perhaps less friction and more rpm ? tz350 could you try it and see :2thumbsup

[tjbw]

Memory test for you oldies or know-it-alls. I have a question about the very first Yamaha 250 cc race bikes that came out, the TD1A.
Were the cylinder bores hard anodised or (as another memory flash I had), coated with “channel cracked chrome?”

....

In mid sixties I watched the Yamaha mechanics prepare engines for the Ulster Grand Prix.

It looked like the cylinders had a steel sleeve. I didn't notice any plating. Using a junior hacksaw
they removed part of the sleeve, about 10 x 3mm, adjacent to transfer port.

[husaberg]

In mid sixties I watched the Yamaha mechanics prepare engines for the Ulster Grand Prix.

It looked like the cylinders had a steel sleeve. I didn't notice any plating. Using a junior hacksaw
they removed part of the sleeve, about 10 x 3mm, adjacent to transfer port.

Sounds like the TD1C gully port.
pic to follow.

[Sketchy_Racer]

i wonder if you could machine the sides of a standard piston so there was only a few ribs that contact the cylinder wall. perhaps less friction and more rpm ? tz350 could you try it and see :2thumbsup

Sadly no cigar there, friction is independent of area and by reducing the area you increase the pressure which may lead to failure of the oil film on the cylinder wall causing a mother of all seizures.

Increase lubrication to reduce the coefficient of friction between the piston and cylinder is what we're after, better materials, better oil and more oil film on the cylinder wall.

Perhaps this is why a rich oil mix at 20:1 seems to make more power in our bikes than at 30:1 . Increasing the oil quantity may mean better sealing and less frictional losses??

[TZ350]

322594

Interesting Talk about the TD1C :- http://bridgestonemotorcycleparts.com/index.php?topic=3778.20

[TZ350]

Pictures of Bucket racing Team GPR's 125 2T cylinder build.

322610

First, take a decent look at some good cylinders.

322609

I am not sure the order Seymour did things in but here are some of the progress photos of his CNC work.

322608

Cylinder block, I think it was machined from solid.

322605

Cylinder Fins.

322606

Barrel assembled with sleeve and fins.

322611

[TZ350]

More pictures of Team GPR's 125 2T build.

322618

Massive cylinder head carved out of a single block of alloy.

322615

Its a team effort, and I think it is Reagan who does the fiberglass work.

322616

Scott is the frame man and engine tuner.

322613 322619

Scott with the GPR125 at the Mt Wellington 2 hour.

322612

12 photos is not enough to do this great bike justice.

But hopefully they show something of the dedicated engineering and development work that goes into some Buckets.

In case I have got some detail wrong the full GPR125 story can be found here as well as lots of great videos of Bucket racing:- http://www.kiwibiker.co.nz/forums/showthread.php/150352-Team-GPR/page134

[wax]

Yes, 21mm is WAY too small even for the 250 engine..
And looking at the PV,it wont be working hardly at all with that big space down each side.
You need to add weld to the PV blade side walls and grind pockets further up in the duct to get alot better sealing.
Also looking at the dyno curve the overev thru the gears would be all done at 12500 - that isnt reving hard at all.
From memory the Tyga pipes have way steep rear cones, that wont be helping the dramatic drop off in power past peak.
So I would be getting the header and diffuser length % correct,then lengthen the rear cone to gain some upper mid,without loosing
any overev.
The rear cone is easy enough to replace as a single section.
The other big issue with the 150 cylinders is that they have no port stagger,and the roof angles are very flat.
Fix that and you will pump up power everywhere.
Wobbly can you please expand on port stagger.
I know what it is, I don't know why and I don't know what ports are higher

[peewee]

Pictures of Bucket racing Team GPR's 125 2T cylinder build.

322610

First, take a decent look at some good cylinders.

322609

I am not sure the order Seymour did things in but here are some of the progress photos of his CNC work.

322608

Cylinder block, I think it was machined from solid.

322605

Cylinder Fins.

322606

Barrel assembled with sleeve and fins.

322611


nice. definatly the coolest stuff on the intrnet around here. is there any money that can be won in that class or is it trophies only ?

[jonny quest]

Port stager is simply exactly the way it sounds. A transfers open sooner than B transfers, or vice versa. C typically always opens last.

[wax]

Thanks I know what it is. What Is the benefit and theory behind it

[TZ350]

Is there any money that can be won in that class or is it trophies only ?

No no money to be won, trophies only (if your lucky) but lots of good will and friendly fun.

You don't need to go to this effort to have a good ride, plenty of people have a great time competing on fairly basic bikes like the mighty FXR150 with just a few modifications for the track. But to be at the pointy end you pretty much have to have put some effort into developing a good race package.

Money would probably spoil it.

[jasonu]

nice. is there any money that can be won in that class ?

:killingme:killingme:killingme:killingme:killingme :killingme:killingme:killingme:killingme:killingme :killingme:killingme:killingme:killingme:killingme :killingme:killingme:killingme:killingme:killingme :killingme:killingme:killingme:killingme:killingme :killingme:killingme:killingme:killingme:killingme :killingme:killingme:killingme:killingme:killingme :killingme:killingme:killingme:killingme:killingme :killingme:killingme:killingme:killingme:killingme :killingme:killingme:killingme:killingme:killingme

[wobbly]

Port stagger is a viable method of affecting the scavenging and trapping efficiency of a cylinder by using the fact that there is residual pressure above the transfers
as they open.
This residual blowdown pressure affects differently the flow regime of each transfer in turn.
The first port to open has flow reversal into the duct - as the case pressure is less than the blowdown pressure.

As a general rule normal stagger ie A port open first has a positive effect on the low to mid power,and thus is a good choice for situations where there is no PV.
Reverse stagger, with the B,C ports opening first, has a bias toward peak and overev power, loosing some bottom in the process.
This is due in part to the fact that alot more transfer area is gained with reverse stagger as the B port ( generally the biggest ) also has the highest timing and thus
increases the STA commensurately.

I have tried my hardest to run reverse stagger effectively in KZ2 engines, and did gain significant power past peak, but could never get back enough power at 9-10,000
that is the lowest rpm off slow corners for those karts.
Its all very well gaining 5 Hp at 14.000 that the driver hardly notices, but drop 2 Hp at 10,000 where it affects off corner acceleration - and the driver will bitch like hell even
if the outright lap time is 3/10s faster.

[jonny quest]

Sorry wax. To answer how they work best without typing a novel, what type of ex port do you have?

The basic idea is short circuiting into the ex port, and power band you're looking for

[wax]

Thanks wobbly. That's the answer I was looking for.
Johnny the cylinder is a twin reed cylinder, single exhaust port with 126 degree transfers and 198 degree exhaust ports, it's a performance jet ski cylinder for a 550. It's for the vintage class. It pulls about 8000 rpm and I'm primarily concerned about getting low end power for off the bouy turns.

[FastFred]

Bucket racing Face Book page.

https://www.facebook.com/groups/1623256484603284/

Video https://www.facebook.com/wil.killip/videos/1311650092197724/

[chrisc]

More pictures of Team GPR's 125 2T build....

I can testify to the power of this bike, holy crap! Regan seemed to have a hard time getting on the throttle because it has so much of it (for a kart track). It picks the front up bloody everywhere, what a bull! At Edgecumbe we had some great battles and I often won out on my donkey 4 stroke FXR with a holey 19hp and about 35kg more. I think this was purely because I could rider smoother on a technical track with loads of tight corners. I followed him a bunch of laps, seeing him stand it up early just to get on the power as the front lifted. Lines similar to a 600/1000 on such a tight track. It definitely doesn't overly favor high powered bikes as you're on your knee the majority of it. Not to say that the bike isn't a total weapon with massive potential, more so that it looks like a bloody hard bike to ride to it's potential and therefore is very unforgiving... particularly in the wet, which half that Edgecumbe meeting was. Screw. That.

I think Rod's TZ125 chassis AM6 engine with 80cc cylinder is, for me, about right on with power and handling for the tight Mt Wellington, Taumaranui, Edgecumbe tracks. It has enough power to power wheelie if you're aggressive on the throttle and coming out of the infield going clockwise at Mt Welly, you get the front light as you're still on your knee. But, it doesn't have so much that you have to change your riding style and lines significantly just to get around the track, fighting the bike. Actually, the gearing (although I wouldn't highly rate the gearbox) is pretty good on Rod's bike. Love it.

Two more (from my perspective, in my opinion at least) examples:
- Kel's KE125 engined NF4 RS125 chassis beast which is no doubt a beautiful bike which looks like a total handful to ride and isn't necessarily always the fastest out there on the tight tracks
- Nathanael's Derbi EBE 80cc NF4 RS125 bike - A solid balance of pretty good power, light riding package, fast rider. Not the most powerful bike out there but the complete package which continuously wins championships.

Just wanted to point out that less is sometimes more, horses for courses and that having a F4 bike with over 30hp isn't always the fastest way to go around the track. It's that sexy, light weight and nimble chassis that really has my eyes :love:

[TZ350]

Absolutely agree +1 ... a total focus on horse power can be a handicap. Fast light easy to ride and nimble is the way to go. There is probably nothing to fear from the horsepower arms race as its pretty much self limiting on a cart track, pity because engine tuning is the bit I like best.

[peewee]

guys has anybody tried or already determined with some certainty what range of crankshaft degrees the mixture is going forward through the reedvalve ? i want to get a idea where to place some piston windows

[peewee]

commom logic says the full window should be uncovered at bdc but ive seen some piston manufacturers have the windows even lower so the full window will be uncovered when the piston edge is covering about half the transfer window on the upstroke which suggest nothing is going forward through the reedvalve until the piston is well on its way up

[wobbly]

Common logic knows nothing.
There is no flow thru the reeds and thus into the case around BDC.
Flow in most all reed engines isnt initiated until TPC on the upstroke, this is when the reeds have finally opened enough for flow to start.
Thus the most effective intake strategy is to have as much area as is possible at TDC, and as much area as is possible via floor and
Boyesen ports.
Holes in pistons are best as low as possible, along with the biggest piston cutaway as is possible to reduce port masking as it rises and drops from TDC.
Here is a typical ( my TZ400 at 11,000 ) cylinder reed intake mass flow and Mach.

[peewee]

thnx wob i figured yamaha knew where the windows needed to be even 30yrs ago since they were very low on the skirt. some wisecos i seen are much higher and probly useless by the time the reedvalve opens. my ktm cylinder is all but finished with only the plating left to do and cutout the piston windows

do you know of any internal photos of the 2017 ktm stuff with the counter balancer ?

[Frits Overmars]

i figured yamaha knew where the windows needed to be even 30yrs ago.Yamaha even knew there shouldn't be any holes at all in piston skirts 40 years ago, and they also knew reeds should be on the cases, not on the cylinders.
But they were not going to throw away the cases they had in stock, so they fitted reeds to the cylinders and made holes in the pistons.


do you know of any internal photos of the 2017 ktm stuff with the counter balancer ?Will this float your boat peewee? https://transmoto.com.au/ktms-two-stroke-counter-balancer/?utm_content=bufferc9179&utm_medium=social&utm_source=facebook.com&utm_campaign=buffer
322629 322630 322631 322632

EDIT: It's advisable to keep your brain in gear when reading through the above KTM link, because you will also encounter pearls of wisdom like
Two-stroke engines have.. always been notorious for vibrating way more than their four-stroke counterparts.

[Frits Overmars]

Holes in pistons are best as low as possible.No kidding!
322633

[husaberg]

Will this float your boat peewee? https://transmoto.com.au/ktms-two-stroke-counter-balancer/?utm_content=bufferc9179&utm_medium=social&utm_source=facebook.com&utm_campaign=buffer
322629 322630 322631 322632

EDIT: It's advisable to keep your brain in gear when reading through the above KTM link, because you will also encounter pearls of wisdom like

Frits they are hardly reinventing the wheel there are they...........:whistle:

That counter balancer looks exactly the same as a NSR125 set up amongst others.

[Frits Overmars]

Frits they are hardly reinventing the wheel there are they. That counter balancer looks exactly the same as a NSR125 set up amongst others.True, KTM didn't invent anything here; they just implemented it. Which is not a bad thing.
Here's some more interesting reading from KTM:
https://transmoto.com.au/2017-ktm-exc-range-the-engine-guru/
https://transmoto.com.au/2017-ktm-exc-range-rd-insights/
https://transmoto.com.au/2017-ktm-exc-range-design-philosophy/

[peewee]

frits dont you think a dirtbike would be better off with zeroshift type of transmission? maybe faster laps and less gear wear

[Frits Overmars]

frits dont you think a dirtbike would be better off with zeroshift type of transmission? maybe faster laps and less gear wearSure, and better still with a CVT. And not just dirtbikes but any vehicle.

[wobbly]

Maybe that piston is part of the new Ryger technology Frits - be careful about the NDA you have in place.
We already have case and cylinder induction, that could just about be described as crown induction.

[peewee]

frits do you know why the people from ryger didnt consult with jan , early in their endeavors? seems like his wisdom may have saved them some grief

[jonny quest]

Honda had an automatic transmission in a dirt bike, early 90's I believe.

Cvt at this point would be difficult to get correct on a dirtbike. Cvt's are excellent at from a dead stop to wide open. What they're currently lacking is the on and off throttle, back shifting.... always being in the best RPM range of a 2 stroke.

What if, what if on the RYGER. Let them figure it out. No big deal. We all want to see something exciting, new revolutionary. If it works in the future, great.... but I'm sick of people chastising them. Let them do their thing.

[peewee]

of course let them sort it out but what if you had another set of experienced eyes looking at it

i hear there were 72 scientists, engineers and mathmeticians involved in the eifel tower construction

[jonny quest]

I have a feeling Jan would want nothing to do with that project. This is me assuming

[jonny quest]

What Ga are the titanium GP 2 stroke pipes made of? And what Ti material?

Can they be welded in atmosphere with just a longer leading cup?

[2T Institute]

What Ga are the titanium GP 2 stroke pipes made of? And what Ti material?

Can they be welded in atmosphere with just a longer leading cup?
0.8mm Commercialy Pure CP. You can weld them any way you want more about if they crack to pieces in use. Blue is OK straw colour is bad.
GP pipes must have been made with some orbital tig set up, unless there are dead set genius' that can weld a entire pipe with every join in 1 pass. Frits might have looked over Sam Balders shoulder while he made a pipe :laugh:

[Frits Overmars]

What Ga are the titanium GP 2 stroke pipes made of? And what Ti material? Can they be welded in atmosphere with just a longer leading cup?Here you go Jonny.
322646


0.8mm Commercialy Pure CP. You can weld them any way you want more about if they crack to pieces in use. Blue is OK straw colour is bad. GP pipes must have been made with some orbital tig set up, unless there are dead set genius' that can weld a entire pipe with every join in 1 pass. Frits might have looked over Sam Balders shoulder while he made a pipe :laugh:You got most of it right, 2T Institute. Except, it says .024 on the sheet. That's 0,6 mm, not 0,8.
And yes, I did look over Sam Balders shoulder while he was working on a batch of Aprilia works pipes. They were welded in a gas chamber.

[wobbly]

The sheet of Ti that pic of the material spec was taken off is still on the floor of my workshop.
Best way to weld it is in a chamber as Frits said, but thats a real bitch to handle.
The Jap factories used that method with a large motorized 3 jaw built into the floor to enable easy rotation and fusion with no filler rod.
You can weld it with a big gas lens, but you HAVE to back purge the inside or it will oxidize the inner weld surface and crack immediately.
The prototype Ti pipes I did for a couple of 500GP teams had 0.024" headers and tailcones with 0.032" for the rest.
This setup recovers more evenly the heat lost on the overun into corners, and as it also heats up quicker it makes top end faster as well.

[richban]

Well we are talking about pipes!


So I have this little 125 Cagiva Raptor I ride to work and back. Its winter here and has been rather wet of late. The other night coming home from work it was pissing down, really pissing down. Happy in my Gortex rain gear I set off for home. Wanting this annoying ride out of the way I thought I should be riding the bike on the pipe as it always likes. Well it just would not do it. Riding along in the pissing rain wondering what was wrong with my poor little commuter the only thing I could think of was the water was taking so much heat out of the heavy steel pipe that it just could not work.

On the other side. The last race meeting on the 300 was wet. Man it really went well with a bit of water getting sucked down the open carbs. And the pipes tucked nicely inside the belly pan.

So the simple lesson from all this, is keep your carbs cool and yah pipes hot. The pipes hot in the wet is of importance to the bucket races for sure. With pipes hanging in the wind aka rain the temp changes could be huge.

Please correct my science if I am wrong.

[jonny quest]

There's a product called Solar Flux I used for SS. it's a paste that when applied to the inside of tubing, when heated provided a shielding gas.

Nothing like this for Ti?

[wobbly]

I tried a paste flux on the back of SS and Ti pipes, but found it was a complete bastard to clean off afterwards - especially down inside larger length cones.
The back purged weld seams are perfect immediately, and dont need any after working at all.
And as both Ti and SS are a bastard metal to work with anyway, anything that speeds up the process is money in the bank.
The good thing is that both Ti and SS welded with tig look much better than gas does - unlike the gorgeous welds I can do with gas on Mild steel, that look way better
than anything I can do with the way faster and cheaper argon/tig method.
For any sort of production/GP work, cold wire over tig is the only way to go - see the pic.

[ken seeber]

Wob, beautiful.
Now, what's the go with the obviously intentional extended welds, beyond the weldment? To avoid possible cracking emanating from the end of the junction?

[peewee]

wob regarding the inflow at TPC. would that be at full noise on the pipe? surely off the pipe inflow may not start until much later ?

[wobbly]

Yes Ken, the extended weld bead stops cracks starting in the corners that are natural stress raisers otherwise.
Yes Peewee, I only have a mass flow readout for 8000 rpm for that engine ( just coming onto the pipe ) and it does start inflow later - but not a hell of a lot.
At that rpm the intake length wave tuning is out of sync with the case depression, giving rise to the big changes in inflow - as the reed see's very different
pressure ratios occurring on each side of the petals as they start to lift off the seat.

[F5 Dave]

I went to Emex a couple of weeks ago and went to a few seminars about 3D printing.
Last night I had a dream about titanium printed pipe.

[husaberg]

In mid sixties I watched the Yamaha mechanics prepare engines for the Ulster Grand Prix.

It looked like the cylinders had a steel sleeve. I didn't notice any plating. Using a junior hacksaw
they removed part of the sleeve, about 10 x 3mm, adjacent to transfer port.


Sounds like the TD1C gully port.
pic to follow.


322594

Interesting Talk about the TD1C :- http://bridgestonemotorcycleparts.com/index.php?topic=3778.20

Gully port diagram plus apicture of the real thing

[chrisc]

I think there might be a freetech 50 build in my future and the KTM SX 50 engine might be the way I go. The cylinders look pretty nicely made! Naturally, Rion Janssen's cylinder work caught my eye on Facebook. He's from Barcelona, Spain and works under JTMX Racing.
He gave me permission to post some photos of his work here and I've help him set up an account here so hopefully we can get some commentary on what he's been doing and his results.

More photos here: Album link (https://www.flickr.com/photos/sonscc/albums/72157670452090256/with/28018461826/)

I might be looking in the wrong places but I don't see to much discussion on the KTM 50 engines. If anyone has any other helpful links, post them up!

https://c7.staticflickr.com/8/7413/27772211030_1ef79d8b13_c.jpg (https://flic.kr/p/Jj8QLE)
Rion3 (https://flic.kr/p/Jj8QLE) by Chris Cain (https://www.flickr.com/photos/sonscc/), on Flickr

https://c3.staticflickr.com/8/7799/28018461426_9193187cbd_c.jpg (https://flic.kr/p/JFTWr9)
Rion4 (https://flic.kr/p/JFTWr9) by Chris Cain (https://www.flickr.com/photos/sonscc/), on Flickr

https://c3.staticflickr.com/8/7666/27772210890_52e71de01a_c.jpg (https://flic.kr/p/Jj8QJf)
Rion5 (https://flic.kr/p/Jj8QJf) by Chris Cain (https://www.flickr.com/photos/sonscc/), on Flickr

https://c8.staticflickr.com/8/7388/27975498711_69ca1cf157_c.jpg (https://flic.kr/p/JC6K7F)
Rion7 (https://flic.kr/p/JC6K7F) by Chris Cain (https://www.flickr.com/photos/sonscc/), on Flickr

https://c3.staticflickr.com/8/7308/28018461826_f45401f0b0_c.jpg (https://flic.kr/p/JFTWy3)
Rion1 (https://flic.kr/p/JFTWy3) by Chris Cain (https://www.flickr.com/photos/sonscc/), on Flickr

[Tim Ey]

I have worked on a few old 50cc Mopeds and allways was sad that there was not a single cylinder which fitted my needs - this is the first state of the art 50ccm cylinder ever made.
It has some issues (to big exhaust at the flange, auxilaries designed to suit the 65SX Rave) but I can't wait to work on it
322757

[41juergen]

As I'm going to setup a new set of barrels I want to do the small radius on the top of the ex port. Is approx. 2 mm too less or in the right ball park and the aux port can also get a small radius, right?

[cotswold]

[QUOTE=chrisc;1130983787]I think there might be a freetech 50 build in my future and the KTM SX 50 engine might be the way I go. The cylinders look pretty nicely made! Naturally, Rion Janssen's cylinder work caught my eye on Facebook. He's from Barcelona, Spain and works under JTMX Racing.
He gave me permission to post some photos of his work here and I've help him set up an account here so hopefully we can get some commentary on what he's been doing and his results.

More photos here: Album link (https://www.flickr.com/photos/sonscc/albums/72157670452090256/with/28018461826/)

I might be looking in the wrong places but I don't see to much discussion on the KTM 50 engines. If anyone has any other helpful links, post them up!

sorry TZ, fast fred

[chrisc]

Chris, in my humble opinion this is the way F5 should be heading, there are no, repeat no replacement bikes for F5 on the NZ market, I have a watch on all RS50 bikes that pop up on TM and there have been 0 in the past year. I have done my best to stir up enthusiasm for the class but it's tough when it's all built around antique mopeds. There are plenty of spare parts out there for the KTM 50, hell my ancient Honda uses KTM pistons which are an off the shelf item, KTM65 bottom end with a kTM50 top and you are away with a modern, cheap and reliable race bike.
I stand corrected there is one on TM for upwards of $3700

I will be asking for help on putting a submission to MNZ rules for a freetech rule change for F5 next merry go round.

Let's not discuss the rules for F5 in the ESE thread, rather the 50 thread, or the rule change submissions thread.

I partly agree with you on running freetech rules though but I'm on the fence considering the fun being had in F5 and growth seen at least in Auckland. The biggest challenge F5 faces is getting more riders keen to build a bike a ride it. Frankly, the rules are there right now for someone to build a F5 bike and run it if they want without needing a rule change. Yes a MX engine would make it slightly easier and potentially slightly less costly but it's definitely not the core reason why we don't have more F5 riders/bikes. Getting riders/builders keen is the part of this class that needs to improve because unfortunately there are only so many Dave Trustrum spec 50s for people to just buy and ride (lucky me).


I have worked on a few old 50cc Mopeds and allways was sad that there was not a single cylinder which fitted my needs - this is the first state of the art 50ccm cylinder ever made.
It has some issues (to big exhaust at the flange, auxilaries designed to suit the 65SX Rave) but I can't wait to work on it
322757

Just to confirm, is this a mold of the KTM SX50 exhaust duct?

[karter444]

if a barrel has been raised to obtain the desired port timings and the bottom of the transfers end up above the piston at bdc by about 1 mm is there any benefit grinding the transfers down to match the piston height , does this increase the transfer sta
cheers

[lodgernz]

Chris, in my humble opinion this is the way F5 should be heading, there are no, repeat no replacement bikes for F5 on the NZ market, I have a watch on all RS50 bikes that pop up on TM and there have been 0 in the past year. I have done my best to stir up enthusiasm for the class but it's tough when it's all built around antique mopeds. There are plenty of spare parts out there for the KTM 50, hell my ancient Honda uses KTM pistons which are an off the shelf item, KTM65 bottom end with a kTM50 top and you are away with a modern, cheap and reliable race bike.
I stand corrected there is one on TM for upwards of $3700

I will be asking for help on putting a submission to MNZ rules for a freetech rule change for F5 next merry go round.

Tim, do I take it that you're planning to ask for factory race engines to be allowed in F5?

[wobbly]

Lowering the transfer bottom edge to BDC for sure increases the STA, but it also dramatically increases piston cooling
from the transfer streams attaching to it,right from the timing edge.

[peewee]

I think there might be a freetech 50 build in my future and the KTM SX 50 engine might be the way I go. The cylinders look pretty nicely made! Naturally, Rion Janssen's cylinder work caught my eye on Facebook. He's from Barcelona, Spain and works under JTMX Racing.
He gave me permission to post some photos of his work here and I've help him set up an account here so hopefully we can get some commentary on what he's been doing and his results.





could you ask him what he uses to get a fairly smooth surface on the tunnel walls ? ive tried a few things but nothing has worked good so far

[wobbly]

Rex-Cut cotton fiber mounted points are perfect for polishing plated port edges, and alloy ducts.

[peewee]

thanx mate ill order up a few

[Tim Ey]

Just to confirm, is this a mold of the KTM SX50 exhaust duct?

It is. These are some as well.

322808322809322806322807

Also on pit-lane.biz there is a thread where Jan and Frits comment on the KTM 50SX.
Do not know whether it was in this area
http://www.pit-lane.biz/f31-50cc
or in the "All you wanted to know" Stuff...

By the way: Does anyone know the porting timings of a 300cc trial engine?

[wax]

Wobbly
The mismatch in the exhaust port duct to header pipe is not always there in all engines. Assuming I have an exhaust manifold I can grind one into, do you think it's worth while doing ??

[Frits Overmars]

Wobbly
The mismatch in the exhaust port duct to header pipe is not always there in all engines. Assuming I have an exhaust manifold I can grind one into, do you think it's worth while doing ??You don't want a mismatch at all Wax. And if there is one, try to eliminate it by adding, not removing, material.

[jonny quest]

Most of the high performance 2 stroke dirt bikes case reed window is just square, and not flowed into the case transfer ducting. Some even with sharp corners that just end.

Is there really any power to be had by modifying this section?

[wax]

You don't want a mismatch at all Wax. And if there is one, try to eliminate it by adding, not removing, material.
Thanks Frits

[wobbly]

Frits is on the money as usual, the JTMX cylinder that is shown above is a classic case.
The steps into the duct are way better than it would be if the steps were ground away - but reversing the shape and
adding material to the manifold to adopt the oval exit shape of the cylinder, then transitioning out the the round
header will make more power.
Again just by eye i can see that the cylinder exit area is too big, and the Aux tunnels down the side should be way bigger and only blend into
the round header shape right at the end of the spigot.

Re the reed box shape into the case - a bit like the recent trend of reducing the Ex duct exit area, the exit of the reed tunnel is also being reduced in area
as it transitions as well.
This keeps the velocity of the streams exiting the reed tips higher thus aiding pressure recovery instead of it simply dumping into a big cavity.
In many cases ( literally ) what you would think ( by eye ) was a big flow discontinuity ie a corner near the entry to the transfer duct is in fact better than a nice radius as
the smaller exit area affects the velocity more than the flow direction improvement.

One area I want to look into is that after seeing Frits sketch of the flow from the reed ports spilling over the sides, guided in part by the big stuffer inserts - is to create side ducts
in the case to harness this side flow and direct it straight into the bottom of the transfer entry's.
And combining this with reducing the reed box vertical exit area as much as possible.

[jfn2]

Hello Wobbly;
Here are some pics of a reed intake port, one stock and one slightly modified.
http://www.kiwibiker.co.nz/forums/album.php?albumid=5033
Are you saying to leave the sharp edges and not to round the corners as in the modified pic?
Also I would like to see Frits' sketch of the flow from the reed cage, with his permission of course.
Also I would like to speak to you about a Yamaha YZ125 pipe but I don't have enough posts to PM you.
Thank you very much. jfn2

[wobbly]

I think Frits sketch is on here somewhere,showing the flow spill out sideways from the reedblock ports.
Yes grinding away the sides of the reed tunnel reduces the velocity,and does nothing to allow extra flow to be drawn into
the transfer duct entry - as you would think looking at it.
What you need to do now is reduce the vertical height of the reed box exit, and while you are at it weld in a couple of say 4mm strips right over
the tops of the flywheels to form a ramp - with just the width of the big end between them.
There is no need to have any more than the max reed tip lift height, where the reeds end, and the duct can get smaller in height further inward.
A nice radius on the boost port entry does help here.

[jonny quest]

With a counter rotation crank against inlet flow, it cost 1 to 2 HP if I remember correctly.

Wouldn't building a divergent floor above crank wheels on a standard rotation arrangement really have no effect?

[jfn2]

Wobbly ;
Here are some other pics.
http://www.kiwibiker.co.nz/forums/album.php?albumid=5033
Except the radius for the boost port opening, is this something of what you mean?
And am I to add material clear back under the reed block, or at least back to the reed block, top and bottom?
jfn

[karter444]

Lowering the transfer bottom edge to BDC for sure increases the STA, but it also dramatically increases piston cooling
from the transfer streams attaching to it,right from the timing edge.

Hi Wob thanks for the reply I would have thought having a cooler piston edge would be better but are you saying that having the transfer stream attach itself right from the timing edge is not what you want
cheers

[wobbly]

JFN2 - yes adding epoxy/weld to the floor to speed up and direct the flow over the flywheels ( even though they are spinning in the right direction )
will help power.
And if you can fill in the floor and roof so that the petals are just clearing at full lift,then this will help as well.

Richard - as the majority of bulk flow is around BDC,then you want the streams to attach right at the timing edge, not jump over a ledge
then onto the piston crown.

[lodgernz]

JFN2 - yes adding epoxy/weld to the floor to speed up and direct the flow over the flywheels ( even though they are spinning in the right direction )
will help power.
And if you can fill in the floor and roof so that the petals are just clearing at full lift,then this will help as well.


Wobbly, I assume you've only been talking about case reeds in this discussion. Do you have any tips for improving the flow in a cylinder reed engine such as the Honda NSR 50, where the reed box empties into both the case and the cylinder?

[wobbly]

Yep, the whole deal with cylinder reeds to is get as much unobstructed flow area directly into the case as you can.
Thus floor ports and Boyesens should be as big as possible.
Then the piston skirt should be as short as possible, and any holes as low and as wide as you can get them on the skirt.
One idea that works well is to turn normal Boyesens into partial floor ports by hogging them out downwards, and then cut away the rear vertical wall of the B transfer
entry in the case at an angle.
Going higher with the Boyesens upsets the flow regime in the B duct too much, and the flow ends up running across and crashing into the transfer divider wall.

[SwePatrick]

Crazy swedish build, 1st testdrive, no tuning yet.
Evinrude twostroke v8 with pipes in an Volvo amazon(dragracechassi) ;)

https://www.youtube.com/watch?v=mrhsUXnodfw&feature=share

[FastFred]

Crazy swedish build, 1st testdrive, no tuning yet.
Evinrude twostroke v8 with pipes in an Volvo amazon(dragracechassi) ;)

https://www.youtube.com/watch?v=mrhsUXnodfw&feature=share

<iframe width="560" height="315" src="https://www.youtube.com/embed/mrhsUXnodfw" frameborder="0" allowfullscreen></iframe>

Love it ..... :yes:

[wax]

Yep, the whole deal with cylinder reeds to is get as much unobstructed flow area directly into the case as you can.
Thus floor ports and Boyesens should be as big as possible.
Then the piston skirt should be as short as possible, and any holes as low and as wide as you can get them on the skirt.
One idea that works well is to turn normal Boyesens into partial floor ports by hogging them out downwards, and then cut away the rear vertical wall of the B transfer
entry in the case at an angle.
Going higher with the Boyesens upsets the flow regime in the B duct too much, and the flow ends up running across and crashing into the transfer divider wall.
That's interesting wobbly thanks for that. I'm working on a cylinder reed now. Would it pay to have the biggest reeds possible in a cylinder reed system then ? What the downside of having to bigger a reed

[wobbly]

The downside is loosing velocity thru the reed ports.
As an example if you take a CPI Cheetah 400 cylinder for a Banshee and use the VF3-CR250 reedblock that its made for
then fit the smaller VF3 - CR125 block with a spacer ( as the reed block is 6mm narrower ),the power increase is 6 RWHp in the mid
and 2 RWHp at peak.
What tends to happen with the smaller reed is that as you push toward its flow limit by making more power, the petals will stay open longer, due to the increased velocity and column inertia.
In most cases a VeeForce in the hole will be able to flow more than is needed, and keeps the velocity up by utilizing low tip lift thru the large port area available.

[wax]

That makes sense. Thanks for that, basically the smaller reed ends up using the mass weight of the air traveling at a higher speed to stuff the cases more. Thanks a lot for that

[wax]

That makes sense. Thanks for that, basically the smaller reed ends up using the mass weight of the air traveling at a higher speed to stuff the cases more. Thanks a lot for that

The cylinder on the right is the one I'm using. As you can see it has a massive reed area. I was looking to use v-force reeds in it. But this may increase the reed volume to much. This is a 550 Kawasaki Jetski cylinder

[dented]

Hey sorry to butt in on this thread, Im trying to get hold of wobbly to see if I can get a custom pipe job done in Tauranga. Wobby, if you see this can you reply with some way to get hold of you please :)

[wobbly]

Well the smaller reed may not in fact fill the case " more ".
All depends upon how big the " big " reed is and how small the other.
As the small reed can quickly run out of intake area, the Cheetah version I gave is limited to about 120 Crank Hp with the CR125 VF3.
Over that the CR250 beats it.

EngMod gives you the port and tip lift area /power capability of any reed,so if you want to get an optimum setup in the 550 then PM me and
get the stock block sorted first.

[lodgernz]

Thanks again Wobbly.

[peewee]

wax ive put numerous cylinders in engmod and in every instance the intake and reeds seem to be undersized. i would dare guess your intake and reed block wont be to big

[bjorn.clauw.1]

Yep, the whole deal with cylinder reeds to is get as much unobstructed flow area directly into the case as you can.
Thus floor ports and Boyesens should be as big as possible.
Then the piston skirt should be as short as possible, and any holes as low and as wide as you can get them on the skirt.
One idea that works well is to turn normal Boyesens into partial floor ports by hogging them out downwards, and then cut away the rear vertical wall of the B transfer
entry in the case at an angle.
Going higher with the Boyesens upsets the flow regime in the B duct too much, and the flow ends up running across and crashing into the transfer divider wall.

322927322928

Hi Wobbly, so above pictures would be the way to go for those of us with cilinder reeds. Maybe putting an extra ramp on the top of the boyesen ports to angle the flow even more downward into the case (guiding it as much away as possible from the b port entry).

[husaberg]

The downside is loosing velocity thru the reed ports.
As an example if you take a CPI Cheetah 400 cylinder for a Banshee and use the VF3-CR250 reedblock that its made for
then fit the smaller VF3 - CR125 block with a spacer ( as the reed block is 6mm narrower ),the power increase is 6 RWHp in the mid
and 2 RWHp at peak.
What tends to happen with the smaller reed is that as you push toward its flow limit by making more power, the petals will stay open longer, due to the increased velocity and column inertia.
In most cases a VeeForce in the hole will be able to flow more than is needed, and keeps the velocity up by utilizing low tip lift thru the large port area available.

Wob I can never find the pic.
But the NSR500 with its reeds, only seemed to breath through a small area of them with the intake boot only utilising and being directed 2/3 petals area.
best pics I can find at the moment but I have seen the same I am pretty sure with the YZR500 or RGV500 as well.
322963322964322965322966

[philou]

Hello

I am looking for advice on scavenge for a cylinder 3 transfers port

http://img15.hostingpics.net/pics/422127SCAVENGE.jpg

[Frits Overmars]

I am looking for advice on scavenge for a cylinder 3 transfers port.I wonder why, Philou. Is it a matter of regulations? Anyway, here is a crude suggestion.

[Frits Overmars]

Hi Wobbly, so above pictures would be the way to go for those of us with cilinder reeds. Maybe putting an extra ramp on the top of the boyesen ports to angle the flow even more downward into the case (guiding it as much away as possible from the b port entry).You don't want to guide the inlet flow away from the B-ports, Bjorn. You want it to go into the B-ports; you just do not want it to go only into the B-ports; the A-ports should get their share of the flow as well. I think those Boyesen ports look pretty good as they are right now; I would not add any ramps.

[jfn2]

Here are some new boyesen ports. Please comment and any suggestions will be greatly appreciated. Thank you jfn2
http://www.kiwibiker.co.nz/forums/album.php?albumid=5034
I know that the tabs hanging down into the reed area need to be trimmed. One pic shows a before view. These go into the B-ports first.

[husaberg]

Come on TZ I know you want one of these
http://www.trademe.co.nz/motors/motorbikes/parts-for-sale/other/auction-1117556154.htm

[TZ350]

Come on TZ I know you want one of these http://www.trademe.co.nz/motors/motorbikes/parts-for-sale/other/auction-1117556154.htm

323014

Probably work better than what I have now.

[philou]

I wonder why, Philou. Is it a matter of regulations? Anyway, here is a crude suggestion.

Thanks for your reply.

The cylinder from a French moped, Peugeot 103

not expensive category requires only removing material for the engine.

Expansion Pipe and carburetor 15 mm authorized

for the corners of A-port I thought he had a hook on the rear side is Good idea ?

[Frits Overmars]

for the corners of A-port I thought he had a hook on the rear side is Good idea ?Only if the leading flanks of the A-ports point sharply rearward like the red lines in my drawing.

[1948rod]

hi frits would the mods on a 3 port engine work on a reed or rotary kart 100cc engine. if not would a much wider a port work better with a divider for direction. thanks frits.

[Frits Overmars]

You're not exactly overwhelming me with information, Rod. I would need a little more than the number of ports and the cylinder capacity.
But in general all available real estate in the cylinder circumference should be used for ports. So if there is room to widen the ports, use it.

[wobbly]

3 port engines as used in direct drive karts are very sensitive to even tiny changes to the scavenging regime.
Mess up this and all the bottom end needed will disappear.
They usually have plenty of transfer area with just the 3 ports as drawn, due to the restricted Blowdown capability.
And again, if you go cranking in a heap of transfer STA, and get it mismatched with the Blowdown, you will immediately loose stream velocity
and thus directional control at low rpm.
How many zillion dyno tests do you think the top engine guys have done to get the things to where they are now, and it appears that 3 port
transfers are plenty for a wide power band starting at 8000 and going past 22,000.

[peewee]

guys I had some scrap bits sitting around that I been trying different boyesen ideas. their pointed down but with this style of cylinder I see no other way to do it without grinding them higher which lifts the rear wall of B. which effectively shortens the B tunell as well I suspect ? maybe I could make a small radius on the roof corner of the rear B wall/ boyesen without lifting the wall to high but small radius may not be as effective as bjorns cylinder

[wobbly]

The Cheetah cylinders from CPI have the Boyesen tunnel roof about 20mm down the B port rear wall.
But as Frits said, the dividing septum between the transfers is also dropped down to the same level, such that flow can equally access
both duct entries.

[peewee]

The Cheetah cylinders from CPI have the Boyesen tunnel roof about 20mm down the B port rear wall.
But as Frits said, the dividing septum between the transfers is also dropped down to the same level, such that flow can equally access
both duct entries.

ive seen those cylinders but doesn't that also shorten the transfer tunnels length and reduce the mixture enertia and kinetic energy ? I vaguely remember frits talking about this stuff in the pisa tower

[TZ350]

I vaguely remember frits talking about this stuff in the pisa tower

Page 1000 is your friend. It has links by Husaburg to Frits post about the leaning tower and lots of other great stuff.

http://www.kiwibiker.co.nz/forums/showthread.php/86554-ESE-s-works-engine-tuner/page1000

And the post itself:- http://www.kiwibiker.co.nz/forums/showthread.php/86554-ESE-s-works-engine-tuner/page663?p=1130452963#post1130452963

[philou]

get the same result with only 3 Port scavenging is more difficult

[peewee]

anybody relocate the ring pegs and weld the hole on top with success ? been practicing on old pistons and may give it a go. alittle more practice and I should have full confidence :laugh:

[wobbly]

Yes the Cheetah cylinder has the port dividers well down from the duct/bore edge.
This was done years ago on TZ piston port cylinders, but only on the A port by dropping the bore wall down 15mm in relation
to the B port length that was left stock - it gave a good power increase.
But with the reeds and Boyesen ports in the back I think the flow around the entry to the ducts is more important than the effect of the
duct length.
Something that would be easily tested back to back, but not easy to reverse.

[wax]

Yes the Cheetah cylinder has the port dividers well down from the duct/bore edge.
This was done years ago on TZ piston port cylinders, but only on the A port by dropping the bore wall down 15mm in relation
to the B port length that was left stock - it gave a good power increase.
But with the reeds and Boyesen ports in the back I think the flow around the entry to the ducts is more important than the effect of the
duct length.
Something that would be easily tested back to back, but not easy to reverse.
This is something I plan on trying on my pjs cylinder for the vintage class jet ski.

[wax]

On another point I have a cool old school vintage class Jetski pipe and cylinder I would like to ask wobbly and Frits some questions on. I can do it in pm but I thought since we are all talking two stroke it may be interesting in here. Would anyone be upset if I posted some pics up in this thread

[peewee]

This is something I plan on trying on my pjs cylinder for the vintage class jet ski.

if you have a local dyno test facility you could find any performance difference by using epoxy. different angles and sizes or close the hole completely could all be tried

[RAW]

Interesting ? Frits, Jan, Wobbly your thoughts ?
http://citsengine.com.au/

[TZ350]

I thought since we are all talking two stroke it may be interesting in here. Would anyone be upset if I posted some pics up in this thread

Its all good. Not everyone races Buckets. Love seeing what others are up to with their own projects. Sharing ideas and questions about your own work that all of us to learn from is great.

[TZ350]

anybody relocate the ring pegs and weld the hole on top with success ?

Not us, my efforts ended in failure but plenty of people report they have managed it successfully, its worth a go.

[F5 Dave]

Safer to grind the old peg away. Mini cutoff wheel on a dremel and surgical care will nail it.

[wax]

This is a 550 vintage engine for a Jetski.
I have the rare twin dry pipes for the ski. These were the most powerful pipes they made god this engine, back in the day they had no ignition curve and simply ran a straight line. I have that fixed and am now running a zeeltronic ignition. They used to have a problem with seizing Pistons after a few laps if you even got that far. The engine should be pushing about 100-110 hp accordingly the data I have on them.
My question is the stinger on the pipe is only 22mm which seems to be not much for what's basically two 275cc cylinders producing between 50-55 hp. Assuming that's what it makes. What's your thoughts please. Is it possible to put larger stingers on the pipes with out effecting the rest of the pipe to much.
Thanks for your help.

[Frits Overmars]

Interesting ? Frits, Jan, Wobbly your thoughts ? http://citsengine.com.au/I had a pleasant exchange of thoughts with CITS-inventor Basil van Rooyen (picture) last year. I think I did comment on the CITS engine before, didn't I?
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The stinger on the pipe is only 22mm which seems to be not much for what's basically two 275cc cylinders producing between 50-55 hp...
Is it possible to put larger stingers on the pipes with out effecting the rest of the pipe to much.It's not only possible; it's essential if you want to keep the engine alive. You may loose some overrev but you'll save some pistons and cylinders.
Here is that simple exhaust concept of mine once more (slightly revised). Amongst other things it will give you a guideline for the stinger diameter (D5 in the picture).
323061


I just discovered https://www.hondarandd.jp
Registration is required and you must agree to not spreading the available information, but it may be worth while.

[philou]

for 3 transfert ports scavenging, this document K11B engine, indicates hooks transfers

323063

I have a lot of testing to do and cylinder sacrificed

[peewee]

Not us, my efforts ended in failure but plenty of people report they have managed it successfully, its worth a go.

welding it sucessfully shouldnt be the problem for me. ive been practicing on old pistons and ill do some more practice until my confidence is alittle higher. what im wondering is how 3-4 seconds of heat affects the integrity. ive heard it was common to weld on pistons in the old days but im sure they were made of different alloys

[jasonu]

welding it sucessfully shouldnt be the problem for me. ive been practicing on old pistons and ill do some more practice until my confidence is alittle higher. what im wondering is how 3-4 seconds of heat affects the integrity. ive heard it was common to weld on pistons in the old days but im sure they were made of different alloys

Why not use a thin cutting disk and grind the pin flush with the bottom of the ring groove?

[wax]

I had a pleasant exchange of thoughts with CITS-inventor Basil van Rooyen (picture) last year. I think I did comment on the CITS engine before, didn't I?
323062

It's not only possible; it's essential if you want to keep the engine alive. You may loose some overrev but you'll save some pistons and cylinders.
Here is that simple exhaust concept of mine once more (slightly revised). Amongst other things it will give you a guideline for the stinger diameter (D5 in the picture).
323061


I just discovered https://www.hondarandd.jp
Registration is required and you must agree to not spreading the available information, but it may be worth while.
Thanks Frits for your comment and that link.
I believe some one did the math on your exhaust concept and made a page where mere mortals could put in the figures and get information out the other side.
Does anyone know the link to that I used to have it many moons ago
Cheers

[Frits Overmars]

Thanks Frits for your comment and that link. I believe some one did the math on your exhaust concept and made a page where mere mortals could put in the figures and get information out the other side. Does anyone know the link to that I used to have it many moons agoSeveral people built EXCEL-files around my exhaust concept but I'm not too happy about it.
1: There is hardly any math involved; it doesn't get more complicated than just a square root.
Any pocket calculator can do that, so why complicate things with an Excel-file?
2: In spite of the simplicity of my concept, some geniuses managed to build errors into these Excel-files.
3: If I were to change a default value, these Excel-files would still be around with superseded values.

[wobbly]

The 22mm stingers are stupid small.
We have 250MX engines making 50 Hp and they all use 26mm.
The 2 into 1 Y collector should be over twice the exit area of the two stingers, and I can see that it has been set up to use
an rpm switch driving a solenoid that dumps water into this to vary the back pressure.
Having the back pressure too low increases the bottom end power dramatically to get off the line, then the pipes are choked down to normal pressure
by using jets to control water flow into the Y exit - works very well.

[wax]

The 22mm stingers are stupid small.
We have 250MX engines making 50 Hp and they all use 26mm.
The 2 into 1 Y collector should be over twice the exit area of the two stingers, and I can see that it has been set up to use
an rpm switch driving a solenoid that dumps water into this to vary the back pressure.
Having the back pressure too low increases the bottom end power dramatically to get off the line, then the pipes are choked down to normal pressure
by using jets to control water flow into the Y exit - works very well.
Thanks wobbly and frits.
Ok well maybe i will turn up some 28 mm stinger ( do you think i should go bigger } on the lathe and use the water injection controller i have to dump in water to increase the back pressure, Thats pretty easy to do. I will try and measure the length of the pipes tonight if i get a chance to actually work out their tuned length tacking my port timing in to consideration it will help me when i select a prop for the ski.
Frits I will see if i can work out the details tonight on your calculation and see what it comes back with. time to get into some math huh

[peewee]

Why not use a thin cutting disk and grind the pin flush with the bottom of the ring groove?

yes ill have to grind down the existing pins flush with the groove bottom but for the new pin ill drill one hole from the top down then weld the hole shut and both rings will use the same pin. this method will only require one hole/pin and the fit between pin/hole wont need to be quite as precise. as long as the pin is about the same size as the hole i should be good

the other method of drilling two new holes into the ring grooves will require a precise press fit of .003" from what wiseco told me. this is beyond the capabilities of my available tools or knowledge. besides i have no idea where to get these pins. for the top down method i can probly use most any standard 1/16" steel pin from local hardware store.

ive had pins relocated before but the old codger retired so im on my own now

[trevor amos]

In the past I have used the parallel shank of a metric twist drill, the material quality is assured and drills are available in tiny diameter increments and, they wont break the bank!

cheers, Trevor

[TZ350]

323073323074

I think Yamaha used Piano wire in their TZ pistons. Where the pin is inserted down from the top and secured by bending the end over inside the small blind relief hole drilled into the side.

[Frits Overmars]

I think Yamaha used Piano wire in their TZ pistons. Yamaha would, wouldn't they? After all they're a musical instruments manufacturer.
Piano wire or guitar string is excellent stuff, available in all diameters (1/16" is way too thick, peewee) and one length of string will keep you covered for years.
Where the pin is inserted down from the top and secured by bending the end over inside the small blind relief hole drilled into the side.I do not recomment Yamahas method of bending the pin over inside the hole drilled below the ring groove. Bending will cause plastic deformation of the piston material with according loss of fit. Closing the top of the pin hole by welding is a better method.

[husaberg]

welding it sucessfully shouldnt be the problem for me. ive been practicing on old pistons and ill do some more practice until my confidence is alittle higher. what im wondering is how 3-4 seconds of heat affects the integrity. ive heard it was common to weld on pistons in the old days but im sure they were made of different alloys

I have used a piston with a welded ring land repair before it was used as a replacement was unavailable.
It will destort not a problem with the ring land even if only a few seconds, you can limit the distorting by preheating the piston but be careful.
Burt Munro once used a rather large rivet to repair a piston his this sidekicks Velocette piston it melted again, but in their haste to get the bike ready for the Cust GP they forgot to richen the lean mixture that actually caused the initial melted piston.

[Tim Ey]

I would not close the hole with a TIG Welder - instead I would let the remaining hole above the pin get filled by laser welding. Normally it is expensive as hell, but if you talk to the guy who is working at the machine...

[jonny quest]

Or just peen the hole

[casal-fan]

Citation:
"Will this float your boat peewee? https://transmoto.com.au/ktms-two-stroke-counter-balancer/?utm_content=bufferc9179&utm_medium=social&utm_source=facebook.com&utm_campaign=buffer
322629 322630 322631 322632"

Interesting, but if I´m not wrong KTMs spanish rivals, GasGas, designed an engine blok encorporating a counterbalancer, already in 2003, wich perhaps (seems to be some doubt here) also was used on a 2wheel motorcycle?
It was defo used on the 300cc quad, because I have one of these engines coming from Spain as I write here.
Encouraged by Wobblys build of the KTM250 superkart engine, and the fascination for simplicity, one cyl. one carb. one reed, etc, thought a project revolving on using a 300cc single cylinder conter balanced engine for a track/race motorcycle would be interesting.
Would like to take the oportunity and the lead, to ask for your opinions on something I´ve been meditating a bit on though...
In the article Frits so kindly posted a link to, many exemples of increased reliability are shown. In one of mine preliminary studies regarding the engine I would like to "build", focus was directed to the stress levels imposed on crankshaft components (focus mostly on big and little end bearing). The 300cc engine in question, at 9750 rpm (expected max. power rpm) will put about 15% more load on crankshaft components then f.exe. a CR250 engine tuned for superkart racing at turning 10500 rpm.
Since my knowledge on metalurgics is none, this troubled me a bit. Stress levels could be reduced by lowering rpm, but then power would probably also suffer...
But even more then that, a counter balanced engine, will perhaps put more stress on crankshaft bearings because of the more "unbalanced" crankshaft alone? This troubles me a bit...
Was hoping KTM had written something about this when I saw Frits' link, but nothing, so if somebody has an insightful word about this, please shear, as many times errors can be avoided just by someone saying something.

[wobbly]

The KTM250 I built was based on a 300 bottom end that has the same stroke as the 250.
I dont know if your balance shaft engine is the same 72mm stroke ?
But with the same stroke, but bigger piston,the inertial loads will obviously be greater.
The small ends are bullet proof, the big ends dont seem to be affected as much by the piston weight as they
are affected by the cyclic loads due to rpm - though technically the two go hand in hand.
Main bearings will be loaded more by the extra out of balance forces of the balance shaft spec'd crank - but again these are
bullet proof, especially the roller main as used by KTM on one side.
My opinion would be that if you run the 300 to 10,000 then you are still within the loadings that the 250 see's regularly at 11,000 in roadracing.

[chrisc]

SP125 has a guide for running the front facing airbox on the RS125. Most of us run them and many of us have seen a noticeable effect on making sure they are properly sealed. I was reading the guide and don't quite understand the full effects of one of the recommendations. Can someone please elaborate on the effects of this slid hole:


4: CARBURETTOR VALVE SLIDE
Drill a small hole (Ø 1.0mm ~ 1.5mm) in the outside face of the carburettor slide, centrally, at adistance of 16.5mm from the top of the slide.

http://www.sp125racing.com/rs125-honda-airbox-fitting-instructions.html

[wobbly]

When running a sealed airbox you have residual pressure inside this volume after backing off into a corner.
With higher pressure on the intake side of the slide, and virtually no flow into the engine you will get an excess of
fuel being picked up by the idle circuit.
And when getting back on the gas the engine is then suddenly partially flooded with overun fuel.
The hole in the slide equalizes the pressure on both sides and prevents the airbox pressure from all running under the cutaway and
into the idle circuit.
Helps quite a bit in stopping those highsides that hurt like hell.

[chrisc]

When running a sealed airbox you have residual pressure inside this volume after backing off into a corner.
With higher pressure on the intake side of the slide, and virtually no flow into the engine you will get an excess of
fuel being picked up by the idle circuit.
And when getting back on the gas the engine is then suddenly partially flooded with overun fuel.
The hole in the slide equalizes the pressure on both sides and prevents the airbox pressure from all running under the cutaway and
into the idle circuit.
Helps quite a bit in stopping those highsides that hurt like hell.

Legend, thanks Wob, exactly what I wanted to know.
Step one is making sure all our airboxes are properly sealed. I'm not running the plastic divider which sits in front of the lower triple clamp that prevent air running up into the fairing so going to look into that first because I think there's some improvement to be made there. Not that I'm struggling for straight line performance. Have touched 204km/hr at Hampton and 206km/hr at Teretonga with my light weight.

Edit: This part, #1
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[peewee]

what do they meen over expansion? are they refering to the exh gas or something

http://papers.sae.org/2016-01-1054/

[chrisc]

what do they meen over expansion? are they refering to the exh gas or something

http://papers.sae.org/2016-01-1054/

From the SAE paper preview:
323082

Think they're referring to an asymmetrical power valve setup

[peewee]

ya chris i just seen that as i read further

[casal-fan]

The KTM250 I built was based on a 300 bottom end that has the same stroke as the 250.
I dont know if your balance shaft engine is the same 72mm stroke ?
But with the same stroke, but bigger piston,the inertial loads will obviously be greater.
The small ends are bullet proof, the big ends dont seem to be affected as much by the piston weight as they
are affected by the cyclic loads due to rpm - though technically the two go hand in hand.
Main bearings will be loaded more by the extra out of balance forces of the balance shaft spec'd crank - but again these are
bullet proof, especially the roller main as used by KTM on one side.
My opinion would be that if you run the 300 to 10,000 then you are still within the loadings that the 250 see's regularly at 11,000 in roadracing.

The Spanish 300cc quad engine is (to put it in simple terms) quite similar to the KTM engine.
It is a 72X72 configuration, with balance shaft, triple exhaust port, centrifugal force activated PV, 6 "decently" scaled gears with about 1200rpm loss 5-6th and 1250rpm loss 4-5th shifting at 10.000rpm with secondary gearing to go about 202 km/h. Not bad as a starting point for a track motorbike. Some mecanisms will come off, as the PV activation, perhaps even no PV...
The cranckshaft bearings are the same as KTM, roller on ignition side, ball on the other.
Conrod is 125,5mm but has to change as a quick WWW search showed 2 of these engines with snapped rod just below the little end, showing perhaps that cranckshaft inertia on the upstroke was trying to "spit" the piston through the exhaust, luckily 129mm KTM rod is a match.
Very greatful for the insight and opinion, it was exactly what I was hoping for. Many thanks.

This is the quad, the 300cc engine in question is mounted on:
https://www.youtube.com/watch?v=lnA6znRpU8A

[peewee]

casal-fan the 135mm 380ktm rod is a match as well. as is the 132mm rod from the same era i believe

[Peter1962]

The Spanish 300cc quad engine is (to put it in simple terms) quite similar to the KTM engine.
It is a 72X72 configuration, with balance shaft, triple exhaust port, centrifugal force activated PV, 6 "decently" scaled gears with about 1200rpm loss 5-6th and 1250rpm loss 4-5th shifting at 10.000rpm with secondary gearing to go about 202 km/h. Not bad as a starting point for a track motorbike. Some mecanisms will come off, as the PV activation, perhaps even no PV...
The cranckshaft bearings are the same as KTM, roller on ignition side, ball on the other.
Conrod is 125,5mm but has to change as a quick WWW search showed 2 of these engines with snapped rod just below the little end, showing perhaps that cranckshaft inertia on the upstroke was trying to "spit" the piston through the exhaust, luckily 129mm KTM rod is a match.
Very greatful for the insight and opinion, it was exactly what I was hoping for. Many thanks.

This is the quad, the 300cc engine in question is mounted on:
https://www.youtube.com/watch?v=lnA6znRpU8A

No PV ? What could you possibly gain by doing that ? Would it not be better to mount a servo tot the PV so that is can function the way it should have been done by the manufacturer ?

[JanBros]

No PV ? What could you possibly gain by doing that ?
on a track, you are not supposed to drop out the powerband, so it doesn't matter much how little power there is outside the powerband ?
and it' s more in line with the KISS principle ?

I'm planning on doing the same when (been planning this for 2 years and have the bits already for over a year :o) I'm gonna built a 400cc track bike based on a YPVS 350.

[wobbly]

Using the MX based motors means by default that there are huge rpm drops between gears.
In the KTM250 I built there is 1400 rpm drop hitting 5th gear from 10500.
This is only " just " enough to stay close to peak torque on the upshift and many roadracing karters have real trouble getting
a good compromise between top speed and actually being able to accelerate hard in 5th gear.
Gear it tall enough to be as fast as the aero will allow, and it simple wont have enough power to accelerate at all from 9000 rpm.
Having a servo PV that isnt usually fully open till around 1000 rpm before peak, means that this acceleration issue simply goes away.
But i reiterate, it must be a servo drive, as the mechanical types open over an ever narrowing rpm range as the preload spring is wound up
to lift the full open rpm.
I have seen a TM125 that opened from fully closed to fully open over only 800 rpm when the adjustment was set for full up at 11,000.
Sure you can get different springs wound to help this problem, but why fuck about when we have simple and cheap servo drives and the ECU
to open them in any way the dyno says is best.

[casal-fan]

This project has been on the drawing for years, and several engines were studied to try and make a good picture of what would be easyer to adapt to road motorcycle track.
The KTM sinned (for me) in 2 aspects. The scalling of the only 5speed gearbox, and how difficult it would be to implement an effective second gearing without having to use too much money on custom built sprockets.
This of course is irrelevant for karts, even the CR250 engine is popular and highly sucessful in kart, even if for motorbike road racing, it would be very hard work (and money) to get the gearing suitable. No doubt a Wobbly KTM for superkart will be one to watch for.
Many thanks for the comment on the PV, subject. PV it is then...
The thoughts of not using PV came from the study wich this picture results from, as well as this would of course be an element taken from the equation, it would not weigh anything, cost anything, and it would never break... simple
323090
Also the engine on this video, purpose superkart build 68X68, "based" on the gasgas EC engine (wich I´ll be using as well) seems to have a very similar gear scalling as the pic. above... shame there is no data to see, apart from what the engine sound. It has no PV... doesn´t seem to be missing it either...
https://www.youtube.com/watch?v=4z7KJNVCvtg

peewee, apart from the reassuring comment from Wobbly wich helped me a lot, piston inertia forces calculations on this 300 engine, at the rpms that I think could be viable, and with the 3,5mm longer 129mm KTM rod, are already quite similar-even higher then what the top 66,4X72 superkart engines are showing. Going longer on the rod would make this even worst...
Thought here being to achive the best balance possible - reliability but still have some power gained from rpm.

[twotempi]

323073323074

I think Yamaha used Piano wire in their TZ pistons. Where the pin is inserted down from the top and secured by bending the end over inside the small blind relief hole drilled into the side.

I use a 1.5mm dia needle roller from a little end bearing . Material is tough and also polished so there is no fretting on the ends of the ring. Drill down from the top of the piston allowing for some interference fit (say .05mm ) so the end of the pin is 1 - 1.5mm below top of piston, then weld over the hole to prevent the pin from coming out. You may get a slight swelling of the piston diameter at the position of the pin. Dress this off carefully with a mill-cut file. With a two ring piston you will have the ring gap in the same spot for both rings but this is fine.

[peewee]

I use a 1.5mm dia needle roller from a little end bearing . Material is tough and also polished so there is no fretting on the ends of the ring. Drill down from the top of the piston allowing for some interference fit (say .05mm ) so the end of the pin is 1 - 1.5mm below top of piston, then weld over the hole to prevent the pin from coming out. You may get a slight swelling of the piston diameter at the position of the pin. Dress this off carefully with a mill-cut file. With a two ring piston you will have the ring gap in the same spot for both rings but this is fine.

great suggestion I wonder why I didn't think of a needle bearing :facepalm:. surely theres some laying around the garage. I plan to do more practicing on old pistons this weekend and ill report back how it goes. still im leaning towards the welding idea as the final method but I may see if the peening idea could work also. with simple calipers from last weekends welding I didn't notice any dimensional distortion of the piston skirts but I will be more precise this time with a micrometer . im not even sure the ring grooves distorted but really I didn't pay attention to that. the first thing I realized is its easy to melt off the top corner of the piston :laugh:

[Wizzer10]

The superkart gas gas engine was done by Manfred Wittenborn wiwa a gas gas racing Germany cylinder is 2 exhaust port . AKA rs125

[Peter1962]

The superkart gas gas engine was done by Manfred Wittenborn wiwa a gas gas racing Germany cylinder is 2 exhaust port . AKA rs125

The cases of the gasgas 250 came with a balancer till 1999. The enduro was equiped with a balancer, the MX was not. Those cases were the basis of the 300 that was used in the quad.
For unknown reasons, from 1999 they abandoned the balander, made new cases where a retrofit of the balancer was no longer possible.
When i was enquiring about the possibility of buying the old cases, the belgian importer of gasgas told me that the company no longer has any in stock. I was not very convinced by his explication so i contacted the french importer. He told me that gasgas made an exclusive deal with manfred wittenborn (www.wiwa-racing.de) that only he gets those cases so he can produce and sell the famous wiwa kart engine with balancer. It's a business deal... Is that a bad thing ? No, of course not. But 1 little detail one should take into account : the price for his 250 engine without carburator and without a pipe is 4.700 euro. The engine has another unique feature : it is the only mx based 250 engine that is truely square : 68 x 68

[F5 Dave]

Unknown reasons, well I'll guess. I've owned 200 & 300 & ridden a couple of 250s and latest 300s. Certainly never noticed enough vibration to register whilst dirt riding. And I hate vibration. More weight, expense and parts to go wrong.

Of course dirt riding is very different.

[peewee]

on the new ktm engine i 'think' the links frits posted said the crank and possibly the flywheel is lighter so the counterbalancer doesnt increase the overall engine weight. i havent seen if the balancer shaft rides directly on needle bearings or common ballbearings

[Martin1981]

Wobbly, my KX 500 Rebuild is almost finished and I am thinking about fitting VForce 2 Reeds. As i read what you said about Size and Flow Velocity, do you think it is better to fit a Reedcage made for a 250 or even 125 to make more Power? Or is it best to use the Cage made for the 500? Thanks

[husaberg]

frits dont you think a dirtbike would be better off with zeroshift type of transmission? maybe faster laps and less gear wear


Sure, and better still with a CVT. And not just dirtbikes but any vehicle.

Peewee did you know that the seamless transmission used in Motogp cost over 500,000 Euros (each) and the primary shaft alone, has over 200 parts.
That's likely more parts than some entire two stroke engines have.
With the Hondas there is only one mechanic outside the factory that is even allowed to touch it.

[wobbly]

Martin ,I cant give you any guidance on the reed suitability unless I can put all the data into EngMod along with the engine
power capability to be able to do a valid comparison.
The stock cage may be fine for flow, depends upon the power.
But in general a VeeForce will make better power simply due to having way less tip lift for an equal curtain area.

[Martin1981]

Thanks Wob!

[peewee]

Peewee did you know that the seamless transmission used in Motogp cost over 500,000 Euros (each) and the primary shaft alone, has over 200 parts.
That's likely more parts than some entire two stroke engines have.
With the Hondas there is only one mechanic outside the factory that is even allowed to touch it.

I didn't know the cost but at 500,000 I wonder how much the automotive version would be :eek5:

[peewee]

Martin ,I cant give you any guidance on the reed suitability unless I can put all the data into EngMod along with the engine
power capability to be able to do a valid comparison.
The stock cage may be fine for flow, depends upon the power.
But in general a VeeForce will make better power simply due to having way less tip lift for an equal curtain area.

mine must update automaticly somehow. now you can select teacup passages and bullnose at the sleeve/ inner wall. didn't notice this last time I used it

[husaberg]

I didn't know the cost but at 500,000 I wonder how much the automotive version would be :eek5:

Hopefully a bit less.........
I don't know once it gets to full production a lot less, but its a very complicated bit of kit compared to a CVT even a computer controlled one like a lot of cars have now (ie Mitsubish)

[wax]

Where do you buy the best possible big end bearings, the engine I'm using is known for being hard on bearings I want to make sure I have the best I can get.

[dark art]

I usually use Samarin but INA/FAG seem to be very good as well. IKO has a online catalog but don´t know where to buy

[wobbly]

The manufacturers are all very good, you just need a modern " flat " cage and be sure that you have a set of selected rollers
that are less than a micron different in diameter.

[peewee]

heres a list of the prox lower rod bearings with part# which are made by ntn and probly a few other manufacturers.

16 x 22 x 13 13 pcs Copper / M-Cage 22.162213
18 x 24 x 14 13 pcs Silver / M-Cage 22.182414
18 x 24 x 15 15 pcs Silver / Flat Cage 22.182415F
20 x 26 x 14 16 pcs Silver / Flat Cage 22.202614F
20 x 26 x 15 14 pcs Silver / M-Cage 22.202615
20 x 26 x 15 16 pcs Silver / Flat Cage 22.202615F
20 x 27 x 14 12 pcs Silver / M-Cage 22.202714
20 x 27 x 14 14 pcs Silver / Flat Cage 22.202714F
22 x 28 x 16 14 pcs Silver / M-Cage 22.222816
22 x 28 x 16 18 pcs Silver / Flat Cage 22.222816F
22 x 29 x 14 16 pcs Silver / Flat Cage 22.222914F
22 x 29 x 16 14 pcs Silver / M-Cage 22.222916
22 x 29 x 16 15 pcs Silver / Flat Cage 22.222916F
22 x 29 x 17 14 pcs Silver / M-Cage 22.222917
22 x 29 x 17 16 pcs Silver / Flat Cage 22.222917F
24 x 30 x 17 17 pcs Silver / M-Cage 22.243017
24 x 30 x 17 19 pcs Silver / Flat Cage 22.243017F
24 x 30 x 20 19 pcs Silver / Flat Cage 22.243020F
24 x 31 x 16 - Silver / Flat Cage 22.243116F
24 x 31 x 17 15 pcs Silver / M-Cage 22.243117
24 x 31 x 17 16 pcs Silver / Flat Cage 22.243117F
24 x 32 x 20 12 pcs Silver / M-Cage 22.243220
24 x 32 x 20 16 pcs Silver / Flat Cage 22.243220F
25 x 31 x 20 15 pcs Silver / M-Cage 22.253120
25 x 32 x 16 17 pcs Silver / M-Cage 22.253216
25 x 32 x 16 17 pcs Silver / Flat Cage 22.253216F
25 x 32 x 16.5 17 pcs Silver / Flat Cage 22.253216.5F
25 x 32 x 20 16 pcs Silver / M-Cage 22.253220
26 x 33 x 18 16 pcs Silver / M-Cage 22.263318
26 x 34 x 20 14 pcs Silver / M-Cage 22.263420
26 x 35 x 20 14 pcs Silver / Flat Cage 22.263520F
27 x 34 x 21 16 pcs Silver / M-Cage 22.273421
28 x 35 x 18 17 pcs Silver / M-Cage 22.283518
28 x 36 x 20 15 pcs Silver / M-Cage 22.283620
30 x 38 x 16 17 pcs Silver / M-Cage 22.303816
30 x 38 x 18 17 pcs Copper / M-Cage 22.303818C
30 x 38 x 18 19 pcs Silver / Flat 22.303818F
30 x 38 x 18 19 pcs Silver / Flat 22.303818F-1
30 x 38 x 18 17 pcs Silver / M-Cage 22.303818S
30 x 38 x 19 20 pcs Silver / Flat 22.303819F
32 x 40 x 18 20 pcs Silver / Flat 22.324018F
32 x 40 x 20 18 pcs Silver / M-Cage 22.324020
32 x 40 x 20 20 pcs Silver / Flat Cage 22.324020F
33 x 41 x 20 20 pcs Silver / Flat Cage 22.334120F
34 x 42 x 20 21 pcs Silver / Flat Cage 22.344220F
34 x 42 x 21 21 pcs Silver / Flat Cage 22.344221F
34 x 43 x 20 16 pcs Silver / M-Cage 22.344320
35 x 42 x 20 21 pcs Silver / Flat Cage 22.354220F
35 x 43 x 22 19 pcs Silver / Flat-Cage 22.354322F
36 x 45 x 23 20 pcs Silver / Flat-Cage 22.364523F
37 x 45 x 22 22 pcs Copper / Flat-Cage 22.374522F
38 x 50 x 23 17 pcs Silver / Flat Cage 22.385023F
40 x 50 x 23 19 pcs Silver / Flat Cage 22.405023F

[tjbw]

I had a pleasant exchange of thoughts with CITS-inventor Basil van Rooyen (picture) last year. I think I did comment on the CITS engine before, didn't I?
323062

.....

I just discovered https://www.hondarandd.jp
...

CITS links have been posted here, and on pit lane, quite a few times, without any response. Though I do remember one comment about it infringing some patent.

Thanks Frits for the Honda R & D link :)

[TZ350]

Page 1550 .......



SP125 has a guide for running the front facing airbox on the RS125. Most of us run them and many of us have seen a noticeable effect on making sure they are properly sealed. I was reading the guide and don't quite understand the full effects of one of the recommendations. Can someone please elaborate on the effects of this slid hole:


4: CARBURETTOR VALVE SLIDE
Drill a small hole (Ø 1.0mm ~ 1.5mm) in the outside face of the carburetor slide, centrally, at distance of 16.5mm from the top of the slide.


http://www.sp125racing.com/rs125-honda-airbox-fitting-instructions.html
When running a sealed airbox you have residual pressure inside this volume after backing off into a corner. With higher pressure on the intake side of the slide, and virtually no flow into the engine you will get an excess of fuel being picked up by the idle circuit.


And when getting back on the gas the engine is then suddenly partially flooded with overun fuel. The hole in the slide equalizes the pressure on both sides and prevents the airbox pressure from all running under the cutaway and into the idle circuit.


Helps quite a bit in stopping those highsides that hurt like hell.



The stock cage may be fine for flow, depends upon the power.
But in general a VeeForce will make better power simply due to having way less tip lift for an equal curtain area.



I have recently purchased a used HE-JA barrel and head , just searching for info on what piston they used with it . It's a flat top piston with the ring peg in the centre . Cheers


I've tested a flat top/chamfer piston against dome. All else being equal, the flat/chamfer was a full 1hp better mid on up on a 125

Has anyone tested a flat top vs domed?

I know RSA is domed piston, but for the mere mortal engines the hybrid seems best. Primarily because of excellent flow stability at EX opening. What gives the pure flat top an advantage? Is it more even "push" on piston during expansion?


I would not worry at all about the distance between the ground strap and the piston dome.
Ive run it as close as 1.5 mm and seen no issues at all.

The idea with a flat top is to get the spark gap in the middle of the chamber by using a toroid.

With a dome,the best is a flat roof bathtub, so that the highest turbulent zone from the squish action points at the gap.

But I have found that the toroid also works best with a dome, in many situations like aircooled heads or for use with pump gas ie low bmep. It allows alot more advance and a leaner mixture before deto, making the head way less fussy to tune closer to the limit.

In all cases a sharp edge from the squish into the chamber is the go.

Re port chamfers - you must put chamfers on the Ex before plating or you will grind thru to alloy before getting it correct. The transfers dont need any chamfer before or after plating.

All genuine A kits ran flat tops with central peg, the flat tops for customer Honda RS125 had an offset peg as the cylinder had a wide gap on one side of the boost port - dumb.

There are dozens of good 54mm single ring with center pin. Best I have tested would be a Meteor thin ring lightweight for a TM125 - KZ10 ,has a 4* conic dome.


I have tested flat tops Vs domed and the critical element isnt the piston at all, its the chamber shape.

A flat top with a proper toroid will make more power than a dome with a bathtub, and that is way better than a hemi.
Its all to do with spark gap positioning.

Jan tested the difference in the Aprilia but I havnt seen any comment from him anywhere about the chamber configs that were compared, along with the dome shape.

Many people ( including Yamaha ) have found that the flat top with a chamfer ( and VHM with a radius on the timing edge ) is also superior to the dome - but again it comes back to the chamber shape, and Yamaha for sure has a well developed toroid.

I have also done the hard yards and found the " best " combination when working on the BSL500 piston.
This ended up with the piston edge chamfer matching the squish band width ( at 50% area ) then going flat, this gave the best flow regime from the transfers around BDC and had a good chamber shape as well.

If you combine that with ceramic coating on the chamber/piston, but not anywhere in the squish area, then get clever and find a trick way of cooling the squishband you suddenly have the best elements combined in a synergistic fashion.

Mechanically the two shapes have no advantage over each other - apart from the flat top that wont lock the ring in the groove if deto collapses the top face. If you collapse a domed piston , even a little, it automatically crushes the ring groove,leading quickly to a seizure and a DNF.



a few matters regards to Engmod.

1) when reading the mach index traces on the exhaust, I'm a bit confused at what the numbers actually represent? I am no engineer, but if I see a peak value of .8, does that mean that I am seeing 80% of the speed of sound?

2) I've been trying to replicate the leaning out and retarding Ign on over-rev, to get some more usable power past peak, but when I try to simulate it, it doesn't work. If I keep it on the rich side and adv. the timing, I gain more over-rev??? What am I doing wrong? Thanks in advance!
Re the EngMod questions - Mach 0.8 is as you say 0.8 X Sonic.

If you change the A/F ratio from say 12:1 at say 12,000 to 13:1 at 12500 the Ex temp will rise in the pipe, but just as in reality the lower fuel energy available my not in fact be sufficient to make more power. This is way more likely to be affected by the Delivery Ratio dropping greater than the pipes positive effect from temp has on Hp.

Pulling out advance also affects the pipe temp, but again in many cases the engine efficiency drops way more rapidly than the rise in power seen from the pipe effect. Thus if the bmep drops, then cylinder pressure drops, and more advance will often make better power - just as in reality, again.

What average pipe temps are you using, as this input shows a much greater effect on the Hp curve.

Remember that a solenoid powerjet is not " leaning out " the mixture, it is simply opposing the carbs natural tendency to go rich over the top of the powerband . ie the A/F ratio is forced to remain alot closer to a constant number, not rise to make the engine hotter.


Thanks for the response Wobbly.

I am starting the exhaust wall temp at 325* and have peak power at 425*, I got those numbers from earlier in this thread. Are these numbers close to reality in a MX application?

As you stated above ^^^ I am seeing more over-rev with advancing the timing and keeping A/F constant. So this is due to the delivery ratio dropping off? So does that mean that if I increased the time-area of intake and exhaust the delivery ratio shouldn't drop off as much, allowing the heated pipe to suck more?

Was not aware of the powerjets keeping the a/f more constant on over-rev. Makes sense now that I think about it.

Thanks again!

PS. Wobbly, what combustion efficiency number would you use for a MX 250 with a bore of 66.4mm, and stroke of 72mm?


So if you are running a solenoid powerjet you can simulate its action more accurately by setting the pipe temp at 450 at say 500 rpm past peak.

It will take some fiddling to find the element that is affecting the power the most past peak.
I have found time and again that all it needs is to pull down the Ex exit area to 75% and add a tapered nozzle out to the 100% header area.

The increased pipe temp doesn't make it " suck " more it increases the wave speed,that in turn reduces the effective tuned length.

You can try adjusting the intake length to get it into resonance in the overev, depending upon the harmonic being used and the room available.

A 250 well tuned will sim accurately at around 85 to 88% C.E (combustion efficiency)


heres a list of the prox lower rod bearings with part# which are made by ntn and probly a few other manufacturers.

16 x 22 x 13 13 pcs Copper / M-Cage 22.162213
18 x 24 x 14 13 pcs Silver / M-Cage 22.182414
18 x 24 x 15 15 pcs Silver / Flat Cage 22.182415F
20 x 26 x 14 16 pcs Silver / Flat Cage 22.202614F
20 x 26 x 15 14 pcs Silver / M-Cage 22.202615
20 x 26 x 15 16 pcs Silver / Flat Cage 22.202615F
20 x 27 x 14 12 pcs Silver / M-Cage 22.202714
20 x 27 x 14 14 pcs Silver / Flat Cage 22.202714F
22 x 28 x 16 14 pcs Silver / M-Cage 22.222816
22 x 28 x 16 18 pcs Silver / Flat Cage 22.222816F
22 x 29 x 14 16 pcs Silver / Flat Cage 22.222914F
22 x 29 x 16 14 pcs Silver / M-Cage 22.222916
22 x 29 x 16 15 pcs Silver / Flat Cage 22.222916F
22 x 29 x 17 14 pcs Silver / M-Cage 22.222917
22 x 29 x 17 16 pcs Silver / Flat Cage 22.222917F
24 x 30 x 17 17 pcs Silver / M-Cage 22.243017
24 x 30 x 17 19 pcs Silver / Flat Cage 22.243017F
24 x 30 x 20 19 pcs Silver / Flat Cage 22.243020F
24 x 31 x 16 - Silver / Flat Cage 22.243116F
24 x 31 x 17 15 pcs Silver / M-Cage 22.243117
24 x 31 x 17 16 pcs Silver / Flat Cage 22.243117F
24 x 32 x 20 12 pcs Silver / M-Cage 22.243220
24 x 32 x 20 16 pcs Silver / Flat Cage 22.243220F
25 x 31 x 20 15 pcs Silver / M-Cage 22.253120
25 x 32 x 16 17 pcs Silver / M-Cage 22.253216
25 x 32 x 16 17 pcs Silver / Flat Cage 22.253216F
25 x 32 x 16.5 17 pcs Silver / Flat Cage 22.253216.5F
25 x 32 x 20 16 pcs Silver / M-Cage 22.253220
26 x 33 x 18 16 pcs Silver / M-Cage 22.263318
26 x 34 x 20 14 pcs Silver / M-Cage 22.263420
26 x 35 x 20 14 pcs Silver / Flat Cage 22.263520F
27 x 34 x 21 16 pcs Silver / M-Cage 22.273421
28 x 35 x 18 17 pcs Silver / M-Cage 22.283518
28 x 36 x 20 15 pcs Silver / M-Cage 22.283620
30 x 38 x 16 17 pcs Silver / M-Cage 22.303816
30 x 38 x 18 17 pcs Copper / M-Cage 22.303818C
30 x 38 x 18 19 pcs Silver / Flat 22.303818F
30 x 38 x 18 19 pcs Silver / Flat 22.303818F-1
30 x 38 x 18 17 pcs Silver / M-Cage 22.303818S
30 x 38 x 19 20 pcs Silver / Flat 22.303819F
32 x 40 x 18 20 pcs Silver / Flat 22.324018F
32 x 40 x 20 18 pcs Silver / M-Cage 22.324020
32 x 40 x 20 20 pcs Silver / Flat Cage 22.324020F
33 x 41 x 20 20 pcs Silver / Flat Cage 22.334120F
34 x 42 x 20 21 pcs Silver / Flat Cage 22.344220F
34 x 42 x 21 21 pcs Silver / Flat Cage 22.344221F
34 x 43 x 20 16 pcs Silver / M-Cage 22.344320
35 x 42 x 20 21 pcs Silver / Flat Cage 22.354220F
35 x 43 x 22 19 pcs Silver / Flat-Cage 22.354322F
36 x 45 x 23 20 pcs Silver / Flat-Cage 22.364523F
37 x 45 x 22 22 pcs Copper / Flat-Cage 22.374522F
38 x 50 x 23 17 pcs Silver / Flat Cage 22.385023F
40 x 50 x 23 19 pcs Silver / Flat Cage 22.405023F

[breezy]

CITS links have been posted here, and on pit lane, quite a few times, without any response. Though I do remember one comment about it infringing some patent.

Thanks Frits for the Honda R & D link :)

nautilusengineering.com/ (more hcci)

[Frits Overmars]

THE NAUTILUS CYCLE (HCI/HCCI)
Our unique patent pending design solves the inherent challenges of pre-ignition, poor cold starting, unbalanced combustion, uneven temperatures, limited RPMs...Limited rpms with HCCI. Now that adds a lot to this site's credibility, doesn't it Flettner? :killingme

[Flettner]

Limited rpms with HCCI. Now that adds a lot to this site's credibility, doesn't it Flettner? :killingme

They are sooo last month on this:bleh: Although they probably hold a patent on this system. I'm looking at a better idea (and way simpler) (ish):laugh:

[Lightbulb]

With all the people they employ, if only 4 of them had 1/4 of Flettner's ability and enthusiasm, they would have a whole range of working demonstrate-able engines for the world to see.
Sad, all that cad and no real engine to see..
Neil L

[tjbw]

With all the people they employ, if only 4 of them had 1/4 of Flettner's ability and enthusiasm, they would have a whole range of working demonstrate-able engines for the world to see.
Sad, all that cad and no real engine to see..
Neil L
My thoughts too. I was clicking everywhere, hoping to find video of the engine.

[ken seeber]

In some respects, the idea of the Nautilus piston entrant pre-chamber might be good for the HCCI process.
However, I do what wonder what clearance might be necessary between the piston projection and the hole in the head. This is a practical type question as there are so many design factors that would have to be considered in establishing this clearance: piston rocking, the thermal expansion of the projection, the max running temp of the piston projection and possible thermal deformation, the positional tolerance (ie its true concentricity wrt piston skirt) of the projection on the piston and the positional tolerance of the hole in the head (ie its true concentricity to the bore axis).
Frits, you’re good on this sort of stuff, what sort of clearance do you think necessary? Given it must achieve a claimed 2 to 3:1 pressure ratio above the major compression ratio. I know it is an open question as the rpm, engine capacity and probably the major compression ratio should be known.

[sispeed]

Frits have you been on the Luxembourg Race event last weekend?
There was a 50ccm machine racing class.
While I was changing my jets there was a man greeting me, but I was concentrated on my work.
After finishing the Job I thought was it Frits? But could not find the person to clarify.
Regards Siggi

[Tim Ey]

Has anyone experiences overhauling the Aprilia RS250 / Suzuki RGV crank? Mine needs a rebuild because of too much play at the right conrod.
I want to fit 110mm long TZ250 rods instead of the 105mm series.
1. Is it a good idea to convert the Crank to Washers at the low end? Is it even possible without milling of the crank web on the inside?
2. does anyone have a .dxf file of the base gasket?

[Frits Overmars]

Frits have you been on the Luxembourg Race event last weekend? There was a 50ccm machine racing class.
While I was changing my jets there was a man greeting me, but I was concentrated on my work. After finishing the Job I thought was it Frits? But could not find the person to clarify. Regards SiggiWasn't me, Siggi.

[Frits Overmars]

In some respects, the idea of the Nautilus piston entrant pre-chamber might be good for the HCCI process.
However, I do what wonder what clearance might be necessary between the piston projection and the hole in the head. This is a practical type question as there are so many design factors that would have to be considered in establishing this clearance: piston rocking, the thermal expansion of the projection, the max running temp of the piston projection and possible thermal deformation, the positional tolerance (ie its true concentricity wrt piston skirt) of the projection on the piston and the positional tolerance of the hole in the head (ie its true concentricity to the bore axis).
Frits, you’re good on this sort of stuff, what sort of clearance do you think necessary? Given it must achieve a claimed 2 to 3:1 pressure ratio above the major compression ratio. I know it is an open question as the rpm, engine capacity and probably the major compression ratio should be known.Thanks for the flowers Ken, but I'm not that good. My instinctive reaction: the piston rocking won't allow the necessary clearance. Calculating the piston projection dimensions and volumes is easy enough, assuming there is no leakage. But there will be leakage and I haven't got a clue about its magnitude.

[jonny quest]

Anyone have piston dimensions for a nsr250r mc21?

Looking for wrist pin to timing edge of piston crown please. Thanks!

[breezy]

They are sooo last month on this:bleh: Although they probably hold a patent on this system. I'm looking at a better idea (and way simpler) (ish):laugh:

come on then Flettner, lets have it. spill the beans,,,,:sherlock:

[Lightbulb]

In some respects, the idea of the Nautilus piston entrant pre-chamber might be good for the HCCI process.
However, I do what wonder what clearance might be necessary between the piston projection and the hole in the head. This is a practical type question as there are so many design factors that would have to be considered in establishing this clearance: piston rocking, the thermal expansion of the projection, the max running temp of the piston projection and possible thermal deformation, the positional tolerance (ie its true concentricity wrt piston skirt) of the projection on the piston and the positional tolerance of the hole in the head (ie its true concentricity to the bore axis).
Frits, you’re good on this sort of stuff, what sort of clearance do you think necessary? Given it must achieve a claimed 2 to 3:1 pressure ratio above the major compression ratio. I know it is an open question as the rpm, engine capacity and probably the major compression ratio should be known.

From model glow plug engine experience, a clearance of 0.02mm prevents them from running. They will run with 0.01mm clearance but lack any power.This is for ringless engines. Unless they are looking at the leaking gases from the small area getting super heated then starts combustion. But due to not seeing a working engine , after the Ryger affair, I'm now sceptical.
Neil