ESE's works engine tuner

[jamathi]

A normal exhaust pipe to this form :

http://www.kirikoo.net/images/7philou-20180129-081749.jpg

some exhaust pipe have this shape :

http://www.kirikoo.net/images/7philou-20180129-081834.jpg

Does the shape affect the operation of the exhaust pipe ?

Yes, and quite a lot!

[Jannem]

There is one little extra tidbit that goes with this, that isn't well known. As mentioned when the pressure ratio between the upstream and downstream reaches about 2 the flow velocity reaches Mach 1 and as such the flow velocity can't go any greater by lowering the downstream pressure, and it is generally assumed from that, that the massflow can't go any higher by lowering the downstream pressure.

Seems logical of course, BUT it is only true for certain shapes such as a nice bell mouth entrance etc. When less favorable shapes are used, an orifice being one example (but certainly not the only example), the massflow can be increased by lowering the downstream pressure below the critical Mach 1 ratio. Mach 1 is never exceeded, but the unfavorable flowpath of the unfavorable shape, improves as the pressure is lowered further, causing the massflow to increase. Most flow paths in an engine are not as bad as an orifice, but not as good as a bell mouth either, so there is some wiggle room here and there regarding the massflow vs. upstream to downstream pressure ratio.

Good stuff! I really appreciate the experience based real world knowledge shared here.

[Jannem]

Keep 'm coming Jannem :D.
334950

Ok. :scratch:

Properly shaped, extended, undercut at port roof after the radius to allow the one-sided nozzle to acclerate blowdown flow to higher mach speed.
As the piston descends, the nozzle area ratio will become proportionally smaller with lowering pressure ratio, reducing the chance of separation. If if worked, it wouldn't need much to bump that initial flow, say .5 mach with variety of side effects, lower pressure at port entry and inertia to retain it longer being some of them.

Learning is granted, any chances of winning with this one? :rolleyes:

[Jannem]

Yes, and quite a lot!

Curious minds want to know, if you don't mind to elaborate a little from your experience. Which, I've understood, is nothing short of massive.

[SwePatrick]

I took the opportunity to ventilate the issue to a close friend who is one of the people in charge of engine block at Volvo and he estimated that about 70% of the total development time, is flow optimising on cooling to prevent film boiling.

I think you have a lot to learn the automotive industry!:niceone:



*lol*
Don´t be so easily offended.

But think again.
Quite a difference on what to develop, a race engine or a pollutioncontrolled vehicle.
Twostroke Raceengines = just run it in a happy temp where you got most power, 99.9% around 40c (about 60c marginal before boiling)
Fourstroke commercial engine = need to raise very quickly in temprature so combustion is under control, that make´s the catalysts warm up quick to let them do their work.(watertemps often around 102-105degree, about 10 degree marginal before boiling)

Do NOT mix these ones together and try to use commercial tech into a raceengine.
Keep in mind on what you are actually designing.

[Muhr]

*lol*
Don´t be so easily offended.

But think again.
Quite a difference on what to develop, a race engine or a pollutioncontrolled vehicle.
Twostroke Raceengines = just run it in a happy temp where you got most power, 99.9% around 40c (about 60c marginal before boiling)
Fourstroke commercial engine = need to raise very quickly in temprature so combustion is under control, that make´s the catalysts warm up quick to let them do their work.(watertemps often around 102-105degree, about 10 degree marginal before boiling)

Do NOT mix these ones together and try to use commercial tech into a raceengine.
Keep in mind on what you are actually designing.

I do not think there is anything constructive in this discussion.
You are talking about water tempratur and I am talking about CHF, which are different things.(Film boiling does not mean high water temp)

I think we should leave this discussion

[RomeuPT]

A normal exhaust pipe to this form :

http://www.kirikoo.net/images/7philou-20180129-081749.jpg

some exhaust pipe have this shape :

http://www.kirikoo.net/images/7philou-20180129-081834.jpg

Does the shape affect the operation of the exhaust pipe ?


Logic may at 1st say the more straight forward would be the best. But my experience is so confusing on this that I would need to see real testing data to show differences on more then one engine. I have felt that some pipes I tested made to fit upfront of a bike made more power then the same but under more straight exhaust.

Has it was posted earlier in this topic by woobly, if I remember the most considerably lost of power was if you let the header edges alive and not beat to round them, and if you add welding rod you should clean the interior bumps.... basicly..

Has shown sooner in the topic some aprilias RSW250 had a pipe under and other straight to the back, they probably know how much the difference was caused by this.

[shnaggs]

yes it's 360! However, my experience is very limited when I only used the program for 2 weeks. I have used other programs, so I'm not a total beginner.
I started myself with sketchup to get an understanding of the methodology. It's not as overwhelming at first and has many good exercise videos you can do. (and it free):2thumbsup

Thanks Muhr, keep up the good work

[shnaggs]

You are probably about where I am. If beginning and ending shapes lofted following a guide curve doesn't get you where you want to go then I guess you'd have to have some shapes in-between to loft to. And much of that will probably depend on the capabilities of your CAD software, whether you can loft with more than one guide curve etc.

Can you do a prismatic extrusion of the basic shape of the port in one direction and then use the outline of how you'd like things to look in a different axis to trim that, and then take that shape and fillet edges?

My guess is that whatever you can model is probably not exactly what you want, so you get close, cast and port it until you like it, pull a Vinamold or similar flexible casting from the port and then 3D scan the molding and then clean up the scan and work from that for the next iteration of the model.

cheers,
Michael

Thanks Michael

[shnaggs]

I'm also learning Fusion 360 to draw 2 stroke passages. What I've learned so far:

Don't use surface models (Patch) unless a solid model won't work.
If you use surfaces for passages you will need to use the split body command and then remove the piece you split off. Do that as the very last step.

Model the passages with solid lofts for both the inside and outside parts.
Use the combine feature as a cut to hollow out the part. Remember to turn off the parts you aren't working on.

Lofts like center lines. I can only suggest trial and error to see what lofts will work. Sharp bends will need more sketches to get through the curve, but the best passages I've designed only use a beginning and end sketch connected by a center line with the right curve.

Lohring Miller

Thanks lohring, I think I understand what you are saying.


Oh and sorry for the multi post, I just realized I could have done multi quotes into one post.

[JanBros]

The Aprilia pipes were not that clever, in that Jan had a devil of a time making them work.
This isnt the correct way to do things, ie make a compromised pipe, then be as clever as all hell with the porting to make that pipe work.
If you reverse the % you quoted, to something like 17/59/24% then the steepest diffuser section can become the last, and this is superior in every way for
a very high specific output engine at very high rpm.

I'd been reeding/searching a lot of stuff in this topic using "header" and "diffuser" as search words, and you talked some times about the steepest diffuser being in the middle :


The position of the start of the mid diffuser is the key to making top end and overev power.
Earlyer Aprilia and Honda designs had the steep diffuser starting right after the header, but this pulls the Ex depression down too early around BDC.

It works alot better for power production to space the main cone further along, and make the angle steeper to promote higher depression values by using a shallow last diffuser angle.
This also increases the main body volume.

I have been making the first and last diffusers around the same angle, just coz it feels right, and the sim says fill your boots.



To get a deeper depression later in the cycle this is why we have a 3 section diffuser with a relatively shallow front end, then a long steep main diffuser leading up to the mid.
A short section of shallower angle leading into the belly helps to get a steeper angle on the main diffuser - closer to the mid at around 66%.
So - as a general rule the closer we have the steep section to the mid - the later ,and lower ,in the cycle toward TPC the depression will act.
But if we have the diffuser lengths correct the deep part of the depression will always move from closer to TPO under the peak, then ideally is centred on BDC at peak power rpm, then moves toward TPC
in the over rev area.
Thus - if you feel you need to move the max point closer to TPO you need to move the steep section closer to the header.


seems to me this is what I need for my 50cc CVT MX-Moped. as shorter gearring is not available, high power at high rev's is useless to me. clutch engages at latest at +/- 4000rpm , and it is much more important to be fast out of the many slow corners, than top power and top speed. 70km/h top speed is more than enough, reached at +/- 8.500 rpm -> lot's of power at 5.000 and soem more overrev after the CVT has fully opened.

[SwePatrick]

I do not think there is anything constructive in this discussion.
You are talking about water tempratur and I am talking about CHF, which are different things.(Film boiling does not mean high water temp)

I think we should leave this discussion

Oh but there is.
I understand perfectly what you are talking about, and i say it´s nothing to worry about, that simple!
The more heat dispertion you´ve got the less heat the material will have.
Simple physics, so adding surface area will keep material cooler, and thus more far away from boundarylayer overheating.
And wanting to raise the level even more before CHF accur you can use coolingmedia with higher boilingpoint, or pressurise the water.

http://www.evanscoolants.se/powersports.html

Good luck!

[Tunisti]

Greetings from somewhat snowy Finland!


https://youtu.be/f7_1NxXWOto

First time with decent ice spikes on real (though snowy) track. 9mm front spikes and 7,5mm rear spikes (old racing rule tyre). Skip bit before ½ way of the video for bit better riding (rebound re-adjusted and not-so-fogging helmet because iceroadracing mask).

Spikes to be installed (both 9mm, two different body models)

https://tunisti.kuvat.fi/kuvat/Random%20Pics/IMG_20171207_081938.jpg/_smaller.jpg (https://tunisti.kuvat.fi/kuvat/Random%20Pics/IMG_20171207_081938.jpg)https://tunisti.kuvat.fi/kuvat/Random%20Pics/IMG_20171209_203404.jpg/_smaller.jpg (https://tunisti.kuvat.fi/kuvat/Random%20Pics/IMG_20171209_203404.jpg)

Btw those spikes are turned in CNC lathe one by one, 306 spikes in front wheel and 336 spikes in rear wheel.

[Muhr]

Oh but there is.
I understand perfectly what you are talking about, and i say it´s nothing to worry about, that simple!
The more heat dispertion you´ve got the less heat the material will have.
Simple physics, so adding surface area will keep material cooler, and thus more far away from boundarylayer overheating.
And wanting to raise the level even more before CHF accur you can use coolingmedia with higher boilingpoint, or pressurise the water.

http://www.evanscoolants.se/powersports.html

Good luck!

I have no interest in pie throwing!

respect your opinion

[F5 Dave]

Am I the only one suddenly pondering: I wonder if . . . 10mm ice spikes with knurled sides?:msn-wink:

[Twopints]

On the Clisby one cylinder test engine the exhaust port is placed on the piston thrust face,

but on the multi cylinder engine it is rotated 90 deg and is aligned on the gudgeon pin side of the piston, E.G. the carb and exhaust port are on the same face, has this configuration been used elsewhere, the piston requires a skirt on one side to cover the exhaust port at TDC

also the divider between the crankcase and cylinder base ?

any thoughts gentlemen ?

[Muhr]

also the divider between the crankcase and cylinder base ?

If you only take TM

The J60 is open
OK-closed
MX85-closed when I think about it, maybe it's just halfway down
KZ10c-closed with a half-moon

[Grumph]

On the Clisby one cylinder test engine the exhaust port is placed on the piston thrust face,

but on the multi cylinder engine it is rotated 90 deg and is aligned on the gudgeon pin side of the piston, E.G. the carb and exhaust port are on the same face, has this configuration been used elsewhere, the piston requires a skirt on one side to cover the exhaust port at TDC

also the divider between the crankcase and cylinder base ?

any thoughts gentlemen ?

I went back and looked at your post where there was a pic of an assembled engine - possibly a mockup. It looks to me like he was going to - or had - cast a set of cases as a monoblock with multiple crank chambers. It makes sense then that the prototype single is a one piece case with a coverplate carrying one bearing and the rotary valve.
It also makes sense that the prototype has the inlet and exhaust at right angles as he'd purchased a Yamaha piston I think you said ? If he'd gone ahead with the arrangement of the assembled engine, he'd have had to find suitable pistons - with full skirts.
The arrangement has been used before - but not recently AFAIK. It's awkward - but given the packaging problems he was looking at, probably the easy solution.

[SwePatrick]

respect your opinion

Remember that the next time you feel the need to write some 'cool' oneliner reply´s then.

[ief]

A normal exhaust pipe to this form :

http://www.kirikoo.net/images/7philou-20180129-081749.jpg

some exhaust pipe have this shape :

http://www.kirikoo.net/images/7philou-20180129-081834.jpg

Does the shape affect the operation of the exhaust pipe ?

May I add one, has been bouncing in my head for who knows how long, pretty sure it never been tried? (maybe with good reason)

[Jannem]

May I add one, has been bouncing in my head for who knows how long, pretty sure it never been tried? (maybe with good reason)

Wouldn’t that equal to having a concave belly? :D

Welcome to the distinguished foil hat club!

[ief]

Wouldn’t that equal to having a concave belly? :D

Welcome to the distinguished foil hat club!

No, in my logic that would do the opposite.

Tnx ;)

[wobbly]

If you plot the area's as seen by the wave action traveling along the mid section it would indeed encounter the same rate of change
as having a concave belly section.
And this is good - because ?

[ief]

I was thinking about the 'shape' of the the pressure wave due to differences in temp on the outside of the pipe and the inside.

Witch might be one of the explanations of the straight vs bend pipe.

I know, I only focus on one part...


Just an idear :)

[JanBros]

On the Clisby one cylinder test engine the exhaust port is placed on the piston thrust face,

but on the multi cylinder engine it is rotated 90 deg and is aligned on the gudgeon pin side of the piston, E.G. the carb and exhaust port are on the same face, has this configuration been used elsewhere, the piston requires a skirt on one side to cover the exhaust port at TDC

also the divider between the crankcase and cylinder base ?

any thoughts gentlemen ?

I think this setup definitly needs closed piston pins !

[RomeuPT]

I was thinking about the 'shape' of the the pressure wave due to differences in temp on the outside of the pipe and the inside.

Witch might be one of the explanations of the straight vs bend pipe.

I know, I only focus on one part...


Just an idear :)

I think this little things on the pipe are not enought significant, has I understood with all the past reading the engines with the intake to the front of the bike and exhaust to the back that allow for a straight pipe are not better because of the intake facing the rotation of the cranckshaft against the flow, loss of one or two horse power in a 50cv engine!? And the straight pipe and other improvements possible did not seem to be capable to recover the lost power.

I took this has knowlegde, but I like things to be discussed further :)

[Grumph]

I think this setup definitly needs closed piston pins !

Have a look at twopints bottom pic - Clisby wan't shy of moving everything around....But if those are a pair of boost ports at the back, you may still be right, LOL.

[wobbly]

Well finally boys and girls here is the evidence of what happens when you ceramic coat an Exhaust duct.
The duct was coated with TBC ( Thermal Barrier Coating ) by HPC as is used to coat 4T piston crowns and exhaust pipes.
It was masked off about 10mm into the duct such that the surrounding metal of the port itself would not overheat and create bore distortion.
The result is a drop of about 1Hp all the way up the front side, but more importantly the egt at lower rpm is about 50*C hotter.
From this area upward the deto level was over double that of the stock uncoated cylinder, and under normal test conditions I would have richened the jetting
to try to get back to the same deto level - obviously to the detriment of an extra power loss.
But this test shows that the actual top end jetting was all but identical.

Based on this I now firmly believe in changing the cylinder cooling regime ( TM KZ10C ) to increase the water flow under the duct, and to extend that cooling right out
to the back of the pipe spigot flange face.
I am permitted to machine say 5mm off the cylinder duct exit - and increase the flange thickness by the same amount, allowing a water passage within the fixing flange
to lengthen the cooled length of the exit flow.

[Jannem]

Well finally boys and girls here is the evidence of what happens when you ceramic coat an Exhaust duct.
The duct was coated with TBC ( Thermal Barrier Coating ) by HPC as is used to coat 4T piston crowns and exhaust pipes.
It was masked off about 10mm into the duct such that the surrounding metal of the port itself would not overheat and create bore distortion.
The result is a drop of about 1Hp all the way up the front side, but more importantly the egt at lower rpm is about 50*C hotter.
From this area upward the deto level was over double that of the stock uncoated cylinder, and under normal test conditions I would have richened the jetting
to try to get back to the same deto level - obviously to the detriment of an extra power loss.
But this test shows that the actual top end jetting was all but identical.

Based on this I now firmly believe in changing the cylinder cooling regime ( TM KZ10C ) to increase the water flow under the duct, and to extend that cooling right out
to the back of the pipe spigot flange face.
I am permitted to machine say 5mm off the cylinder duct exit - and increase the flange thickness by the same amount, allowing a water passage within the fixing flange
to lengthen the cooled length of the exit flow.

Good stuff, thank you! Doesn’t leave much room for speculation...

[Jannem]

May I add one, has been bouncing in my head for who knows how long, pretty sure it never been tried? (maybe with good reason)

Taking this a into a bit different direction, an internal plate dividing the rapidly expanding part of the diffuser in two halves might improve the pressure recovery. The resulting two halves would have smaller rate of area expansion change, which should reduce the flow separation. Perhaps even 4 sections with horizontal and vertical crossing plates could be used.

[dutchpower]

Did you not test it on the same day Wobble

[TZ350]

Well finally boys and girls here is the evidence of what happens when you ceramic coat an Exhaust duct.
The duct was coated with TBC ( Thermal Barrier Coating ) by HPC as is used to coat 4T piston crowns and exhaust pipes.
It was masked off about 10mm into the duct such that the surrounding metal of the port itself would not overheat and create bore distortion.

The result is a drop of about 1Hp all the way up the front side, but more importantly the egt at lower rpm is about 50*C hotter.

From this area upward the deto level was over double that of the stock uncoated cylinder, and under normal test conditions I would have richened the jetting to try to get back to the same deto level - obviously to the detriment of an extra power loss.
But this test shows that the actual top end jetting was all but identical.

Based on this I now firmly believe in changing the cylinder cooling regime ( TM KZ10C ) to increase the water flow under the duct, and to extend that cooling right out to the back of the pipe spigot flange face.

334997

Did you not test it on the same day Wobbly

After all the work involved, ""test same day"", said tongue in cheek no doubt ... :laugh: ..... thank you for doing the work and letting us know Wob.

[jamathi]

Well finally boys and girls here is the evidence of what happens when you ceramic coat an Exhaust duct.
The duct was coated with TBC ( Thermal Barrier Coating ) by HPC as is used to coat 4T piston crowns and exhaust pipes.
It was masked off about 10mm into the duct such that the surrounding metal of the port itself would not overheat and create bore distortion.
The result is a drop of about 1Hp all the way up the front side, but more importantly the egt at lower rpm is about 50*C hotter.
From this area upward the deto level was over double that of the stock uncoated cylinder, and under normal test conditions I would have richened the jetting
to try to get back to the same deto level - obviously to the detriment of an extra power loss.
But this test shows that the actual top end jetting was all but identical.

Based on this I now firmly believe in changing the cylinder cooling regime ( TM KZ10C ) to increase the water flow under the duct, and to extend that cooling right out
to the back of the pipe spigot flange face.
I am permitted to machine say 5mm off the cylinder duct exit - and increase the flange thickness by the same amount, allowing a water passage within the fixing flange
to lengthen the cooled length of the exit flow.

Just as I hoped for, and secretly was convinced of, thank you SO much for publishing this!!
How about now coating the outside of the pipe?
Or even better the inside.....
That might be what Franco and other karting people are looking for:
A quicker responding pipe.....
It might also permit bigger belly diameters!

[Muhr]

Soon I hope all simulation work will be done! Waiting for cylinder deformation on heating and tightened cylinder head.:wait:

Not the best look, but hope it works

[wobbly]

In answer to the "same day " question the answer is no,
BUT, look at the weather correction difference, its tiny as the important factors ( ambient temp and baro pressure ) are very similar.
Usually I would do a back to back, but as the coated cylinder detoed so badly and the egt ended at almost exactly the same level ( 620*C ) i was
more than convinced that the answer wasnt misleading.
The stock cylinder had a deto level of around 1.6V @ torque peak - that same cylinder with the coated port was 3.5V ( on a 0-5V scale ).
That is a level that would eat the piston in a very short time.
The SportsDevices correction makes these dyno runs repeatable on different days within a 1/10 or two of a Hp.
Now I have to find a way to remove the baked on ceramic coating - bugger.

I have ceramic coated the inside of a " homologated " pipe ( ie one that is not allowed to be modified ) and it retained so much surface internal temp that
it lost ALL the bottom end power and then overheated the piston face so much it seized.
The best way to cheat in this department is to acid dip the pipe to reduce the thermal mass, it its been done before in KZ2 where someone at the factory ordered
a small batch of thin wall items from Elto the pipe makers.
So now the tech checkers use a sonic thickness gauge to check this very issue.
If I was allowed to I would make the header and the rear cone in 0.6mm and the rest in 0.8 - that works really well.

[Muhr]

In answer to the "same day " question the answer is no,
BUT, look at the weather correction difference, its tiny as the important factors ( ambient temp and baro pressure ) are very similar.
Usually I would do a back to back, but as the coated cylinder detoed so badly and the egt ended at almost exactly the same level ( 620*C ) i was
more than convinced that the answer wasnt misleading.
The stock cylinder had a deto level of around 1.6V @ torque peak - that same cylinder with the coated port was 3.5V ( on a 0-5V scale ).
That is a level that would eat the piston in a very short time.
The SportsDevices correction makes these dyno runs repeatable on different days within a 1/10 or two of a Hp.
Now I have to find a way to remove the baked on ceramic coating - bugger.

I have ceramic coated the inside of a " homologated " pipe ( ie one that is not allowed to be modified ) and it retained so much surface internal temp that
it lost ALL the bottom end power and then overheated the piston face so much it seized.
The best way to cheat in this department is to acid dip the pipe to reduce the thermal mass, it its been done before in KZ2 where someone at the factory ordered
a small batch of thin wall items from Elto the pipe makers.
So now the tech checkers use a sonic thickness gauge to check this very issue.
If I was allowed to I would make the header and the rear cone in 0.6mm and the rest in 0.8 - that works really well.

Thanks for sharing. great job!
how was the spread of deto around the piston?

[Nath88]

Thanks for the suggestions, the ideas will come in handy.

I have had a bit of success tonight. Used a $12.90 kitset amp from Jaycar as a front end before the bridge rectifier. It worked a treat and gave a very consistent signal.

334893

I used the 0.5W champ amp to amplify the signal from the Piezo disk then passed the output through the bridge rectifier. Very crisp, sharp and consistent signal up to 12,000 rpm.

The Champ amp is based on the LM386 Op amp. With no real load on the output, the output signal was quite high. I need a 5 Volt digital signal for the Arduino input so over the next few nights I will see if I can trade some height for signal width that the Arduino can easily see.

Anyway, very pleased, it feels like progress...... :niceone:

This is great stuff TZ.
Capture and compare those two peaks and I think you're in business.
A low pass filter will trade height for width, but there will be a phase shift/delay which is probably not what you want. If you can sample fast enough to capture the raw signal that would be best.
Consider using the Teensy microprocessor, arduino compatible programming wise but faster processing, also much faster analog input reads. There's also a few extra functions around timing/scheduling that can simplify your programming when you're timing from a crank trigger.

I'm still going down the crankcase pressure route, I've started writing some pseudo-code for measurement vs. crank angle.
I think your system is better since you can have your injection starting very early. You may be able to get accurate fuelling even injecting at the inlet port. I doubt that's possible with crankcase pressure measurement, transfer port injection would be required.

[wobbly]

The dyno curves shown are three pulls averaged, so the run time isn't sufficient to actually eat a piston with that level of deto.

[peewee]

and to extend that cooling right out
to the back of the pipe spigot flange face.
I am permitted to machine say 5mm off the cylinder duct exit - and increase the flange thickness by the same amount, allowing a water passage within the fixing flange
to lengthen the cooled length of the exit flow.

I was thinking about it the other day and why not have the water go down the exh spigot as well. would be easy enough to do. basically all you need is a chunk of what ever material you want to use for the exh spigot, mill, lathe, then youll need to weld on a new steel spigot to the pipe because the exh spigot will have a bit larger OD to allow for the water passage

[diesel62]

I was thinking about it the other day and why not have the water go down the exh spigot as well. would be easy enough to do. basically all you need is a chunk of what ever material you want to use for the exh spigot, mill, lathe, then youll need to weld on a new steel spigot to the pipe because the exh spigot will have a bit larger OD to allow for the water passageIf a ceramic coating makes it worse what about a copper insert that will transfer heat faster?

Sent from my SM-G900F using Tapatalk

[wobbly]

Ha ha Jan, now we can contact " The Great Leader " and tell him straight out he was a wanker all those years ago when he told me
at Philip Island in 2000 that I ( and you ) were completely wrong about duct cooling, because "it took energy away from the pipe ".
Bullshit.
All the KZ10 engines have a tapered spigot OD that fits the pipe ( and you cant change the pipe at all ),I also taper the spigot ID from
the oval shape at the flange face to the round header ID.
This leaves the spigot end as a sharp edge, so I can only CNC plunge cut a water passage a short distance in from the flange face.
I am going to now modify a new cylinder to have the water passages out to the flange face as I have shown before.
Then test using stainless for the spigot, as it conducts heat way less than mild steel, then try a copper one.
But I worry about the strength of a copper spigot,having to hold up the pipe on a kart.

[husaberg]

But I worry about the strength of a copper spigot,having to hold up the pipe on a kart.
Try an Cu alloy with a tiny amount of tin in it.

[jamathi]

In answer to the "same day " question the answer is no,
BUT, look at the weather correction difference, its tiny as the important factors ( ambient temp and baro pressure ) are very similar.
Usually I would do a back to back, but as the coated cylinder detoed so badly and the egt ended at almost exactly the same level ( 620*C ) i was
more than convinced that the answer wasnt misleading.
The stock cylinder had a deto level of around 1.6V @ torque peak - that same cylinder with the coated port was 3.5V ( on a 0-5V scale ).
That is a level that would eat the piston in a very short time.
The SportsDevices correction makes these dyno runs repeatable on different days within a 1/10 or two of a Hp.
Now I have to find a way to remove the baked on ceramic coating - bugger.

I have ceramic coated the inside of a " homologated " pipe ( ie one that is not allowed to be modified ) and it retained so much surface internal temp that
it lost ALL the bottom end power and then overheated the piston face so much it seized.
The best way to cheat in this department is to acid dip the pipe to reduce the thermal mass, it its been done before in KZ2 where someone at the factory ordered
a small batch of thin wall items from Elto the pipe makers.
So now the tech checkers use a sonic thickness gauge to check this very issue.
If I was allowed to I would make the header and the rear cone in 0.6mm and the rest in 0.8 - that works really well.

Retaining all the internal heat would make totally different pipe sizes unavoidable, as I expected.
Finding the right sizes would be difficult I think!
Starting almost from 0 again....
Would 'scaling' an existing pipe be possible?
It could be a starting point I suppose....
All sizes + 10%, up 20% etc.
Think of all the extra energy!

[Grumph]

Try an Cu alloy with a tiny amount of tin in it.

Admiralty bronze. Nearly the same conductivity as Cu but a lot stronger.

[dutchpower]

In answer to the "same day " question the answer is no,
BUT, look at the weather correction difference, its tiny as the important factors ( ambient temp and baro pressure ) are very similar.
Usually I would do a back to back, but as the coated cylinder detoed so badly and the egt ended at almost exactly the same level ( 620*C ) i was
more than convinced that the answer wasnt misleading.
The stock cylinder had a deto level of around 1.6V @ torque peak - that same cylinder with the coated port was 3.5V ( on a 0-5V scale ).
That is a level that would eat the piston in a very short time.
The SportsDevices correction makes these dyno runs repeatable on different days within a 1/10 or two of a Hp.
Now I have to find a way to remove the baked on ceramic coating - bugger.

I have ceramic coated the inside of a " homologated " pipe ( ie one that is not allowed to be modified ) and it retained so much surface internal temp that
it lost ALL the bottom end power and then overheated the piston face so much it seized.
The best way to cheat in this department is to acid dip the pipe to reduce the thermal mass, it its been done before in KZ2 where someone at the factory ordered
a small batch of thin wall items from Elto the pipe makers.
So now the tech checkers use a sonic thickness gauge to check this very issue.
If I was allowed to I would make the header and the rear cone in 0.6mm and the rest in 0.8 - that works really well.

Mayby try this Wobble

We make this for Team Lieqois ( Azuma ) gives more torque
And use sheetmetaal whit the most % of cu in it

[koenich]

Thanks for sharing Wobbly!

Decreasing the thermal mass should improve the transient behavior while coating it will likely need new pipe dimensions in my opinion.

[Peter1962]

Admiralty bronze. Nearly the same conductivity as Cu but a lot stronger.

85-5-5-5 is the best naval bronze.

[teriks]

<snip>
I am going to now modify a new cylinder to have the water passages out to the flange face as I have shown before.
Then test using stainless for the spigot, as it conducts heat way less than mild steel, then try a copper one.
But I worry about the strength of a copper spigot,having to hold up the pipe on a kart.
If you need higher strength than pure Cu, the CuBe alloys are good candidates for that application. Beware of breathing Be dust and fumes though.
https://materion.com/products/high-performance-alloys/copper-beryllium-alloys/alloy-3-10-10x-310

[lohring]

The aluminum pipes like those pictured have been used on 26 cc marine race engines for a very long time. The main reason for all the water cooling is to preserve the o-ring seals. Both the exhaust flange and the header to pipe connection are water cooled. I doubt that you could get one of these engines to detonate since they are happy on 50 octane camp fuel. The basic ideas might be usable on high performance engines, though. We always felt that steel or stainless steel pipes worked better. Again we often ran a water cooled exhaust flange to preserve the o-rings.

335013

Lohring Miller

[peewee]

hey guys im making new fuel tank for my methanol nitro bike. maybe it wont win any beauty awards but atleast now I can get rid of the original 13 liter enduro tank :laugh:. new one will be around 4 liter. ill get a photo when its finished up. only about 2months and it should be warm enough to ride again

[husaberg]

hey guys im making new fuel tank for my methanol nitro bike. maybe it wont win any beauty awards but atleast now I can get rid of the original 13 liter enduro tank :laugh:. new one will be around 4 liter. ill get a photo when its finished up. only about 2months and it should be warm enough to ride again
Make sure you pickel the tank before you use nitro in it.

[Frits Overmars]

hey guys im making new fuel tank for my methanol nitro bike. maybe it wont win any beauty awards but atleast now I can get rid of the original 13 liter enduro tank :laugh:. new one will be around 4 liter. ill get a photo when its finished up. only about 2months and it should be warm enough to ride againHey Peewee, wouldn't it be simpler to use an old extinguisher or similarly-shaped container? By the look of things your new tank might endanger your suit and your private parts....

[SwePatrick]

hey guys im making new fuel tank for my methanol nitro bike. maybe it wont win any beauty awards but atleast now I can get rid of the original 13 liter enduro tank :laugh:. new one will be around 4 liter. ill get a photo when its finished up. only about 2months and it should be warm enough to ride again

And i have started a projekt like your cylinder(well almost anyway)

I have butched up a cylinder to reach everywhere i need to go with my grinders.
I will be a lot of welding before done.
After all is done i will resleeve it.

And a question to all: is 7075 or 6082 aluminium any good for nicasilplating?

Edit: misspelling

335025

[Frits Overmars]

And a question to all: is 7075 or 6982 aluminium any good for nicasilplating?You'd better check with the company that is going to do the job Patrick. Not every company can handle every kind of 'suitable' alloy.

[peewee]

And i have started a projekt like your cylinder(well almost anyway)

I have butched up a cylinder to reach everywhere i need to go with my grinders.
I will be a lot of welding before done.
After all is done i will resleeve it.

And a question to all: is 7075 or 6982 aluminium any good for nicasilplating?

335025

nice project mate.

maybe you can find out what material the cyl is and make a new sleeve from the same material. then weld the sleeve in place and replate it. try to use some kind of heat sink on the top deck if you can, as it will reduce distortion up there. also preheating the cyl to say 93c in a oven also helped me a lot. afterwards I would put it back in the oven so it didn't cool rapidly but im not sure if this did any good

[TZ350]

If you can sample fast enough to capture the raw signal that would be best.Consider using the Teensy microprocessor, arduino compatible programming wise but faster processing.

I'm still going down the crankcase pressure route, I've started writing some pseudo-code for measurement vs. crank angle. I think your system is better since you can have your injection starting very early.

Residual cylinder pressure or crank case pressure, the answer has to be there some place, between us I expect we will find it. I like your crankcase pressure rout as its easier to implement than drilling a fine hole into an NSR cylinder and getting it just 10 deg or so before exhaust port opening. But residual cylinder pressure is precise, there is either residual combustion pressure or not.

335032

The Teensy microprocessor you suggested looks good, this one even has an on board SD card that could be used for data logging. Because adapting a 4T fuel injection system is difficult I might have to consider making my own EFI CPU based on the Teensy.

[husaberg]

The Teensy microprocessor you suggested looks good, this one even has an on board SD card that could be used for data logging. Because adapting a 4T fuel injection system is difficult I might have to consider making my own EFI CPU based on the Teensy.
This is the assembled ECU
You can get the kit cheaper controls fuel and ignition with data logging.
https://www.diyautotune.com/product/megasquirt-ii-ems-system-smd-pcb3-57-assembled-ecu/

you can also just buy the bare ecu cards
http://megasquirt.info/products/diy-kits/microsquirt/
https://www.megasquirtnz.co.nz/
http://microsquirt.com/viewforum.php?f=31&sid=777bd0a047d3fb23ba2bfaeae1858585

[DoldGuy]

And i have started a projekt like your cylinder(well almost anyway)

I have butched up a cylinder to reach everywhere i need to go with my grinders.


335025

SwePatrick,

1851 Cylinder? I am interested in removing 3-3.5 mm from the top of Cylinder (72mm Bore) but was not sure there was enough material....it looks like you removed more than 3.5 mm? Is there enough material left at the studs water jacket area if the bore was a 72mm? Also when going to a 72 bore it removes some of the hook in the transfers (Mains & Seconds), is there enough material there to grind the hooks back in with out hitting the water jacket?

The exhaust does not appear to have hardly any coolant flow area as Wobbly confirmed is much needed. What are your plans for the sub/auxiliary exhaust ports? Is there much material between the water jacket & Port?

[dutchpower]

Hi Frits

Exhaust width smaller and transfer time area from 132 to 128 give's more power in sim

[jbiplane]

And a question to all: is 7075 or 6982 aluminium any good for nicasilplating?
335025
I plate cylinders in my shop and know a bit :)

The rule is simple the more of Cu and Zn in alu alloy the worse nicasil plating.
In general not recomended Cu content more than 0.5% and Zn more than 10%
For hard cases better use sublayer of chemical Ni plating and thermal processing before galvanics. We have as well an experience in complete chemical coating which have some + compare galvanics (required just cosmetical honing to hold oil).

Rather good for nicasil coating is casting of AlSi7Mg

[JanBros]

made my own Excel to calculate FOS-pipes :

http://users.telenet.be/jannemie/FOS%20pipe%20black.bmp

calculates the latest FOS pipes, you can add a Wobbly exhaust duct, and compare the original FOS-pipe with 2/3 stage versions.

the 3 pipes can be overlayed in the graph so it is very easy to compare them.

free for all : http://users.telenet.be/jannemie/FOS%20PIPE%20black.xlsm

if the experts would like to read the text on page 2 to make sure I'm not talking jibberisch :weird: , I would be even more thankful :not:

[SwePatrick]

SwePatrick,

1851 Cylinder? I am interested in removing 3-3.5 mm from the top of Cylinder (72mm Bore) but was not sure there was enough material....it looks like you removed more than 3.5 mm? Is there enough material left at the studs water jacket area if the bore was a 72mm? Also when going to a 72 bore it removes some of the hook in the transfers (Mains & Seconds), is there enough material there to grind the hooks back in with out hitting the water jacket?

The exhaust does not appear to have hardly any coolant flow area as Wobbly confirmed is much needed. What are your plans for the sub/auxiliary exhaust ports? Is there much material between the water jacket & Port?

Ohh,, i dunno name of cylinder, but it is an -98 casting.
And from ~94 to 02 it is the same casting, just minor differences in porting.
I would say you have about 4-5mm before breaking into water, but test/feel with a weldingrod you bend and try to localize waterjacket.
Near/above bolts for bolting it into the the engine it is about 2-3mm at certain places, be careful.

The deck on the cylinder is open, and the 'bungs' or what to call them for the studs are about 22-23mm long downwards from deckplane.
My cylinder is milled off 20mm as is on pictures.
This because i need to mill it 11mm(due to destroked crank), but i don´t trust the studs will sit securely in cast aluminium that is about 12mm.
Therefor i decided to make a new deckplate in the same process as i make the new liner.
Then weld shut the waterjacket against the deck around on the outside..

And finally bore it to spec needed for nicasilplating.

Rgds.


Edit:
I dunno if you can make anything out of this picture.
i try to show with lines were original shape of transfers was.
Green arrows shows were to be careful, but they arent perfect located on picture,, they needs to be lower down, more in height were the nuts are that bolts down the cylinder.
335036

[SwePatrick]

nice project mate.

maybe you can find out what material the cyl is and make a new sleeve from the same material. then weld the sleeve in place and replate it. try to use some kind of heat sink on the top deck if you can, as it will reduce distortion up there. also preheating the cyl to say 93c in a oven also helped me a lot. afterwards I would put it back in the oven so it didn't cool rapidly but im not sure if this did any good

I´ll weld the deck before bore the cylinder to spec for plating.
I planned to heat up whole cylinder after all welding is done to stress relieve it before boring out the liner, and let it cool down slowly.

It is actually the best cylinder by far i have welded in, really easy to weld.

And i came to think of it,, alloy and plating, the plating companies often offer repair of cylinders, with that in mind i guess it is no problem to plate on the welds, But i´ll do as Frits said anyway, just to make sure.
Otherwise i have to make a steel liner.

Rgds.

[katinas]

made my own Excel to calculate FOS-pipes :

http://users.telenet.be/jannemie/FOS%20pipe%20black.bmp

calculates the latest FOS pipes, you can add a Wobbly exhaust duct, and compare the original FOS-pipe with 2/3 stage versions.

the 3 pipes can be overlayed in the graph so it is very easy to compare them.

free for all : http://users.telenet.be/jannemie/FOS%20PIPE%20black.xlsm

if the experts would like to read the text on page 2 to make sure I'm not talking jibberisch :weird: , I would be even more thankful :not:

Thank you very much for your efforts.


Just remember experimentation with exhaust two years ago. I decide to made a new pipe for my Honda Ns 250, so calculating 3 pipe examples. But after all ended with not accurate copy of Honda RS125 (reed) and Aprilia RSA 125 (rotary) pipes (0,8 mm of stainless). Of course dimensions not suitable for NS cylinder, but I just want to feel how these very different shapes pipes work.

Before, tested with STD and Sugaya racing pipes. STD stopped working after 9800 rpm. Sugaya with very nice power band until 10500 rpm.
Both RS and RSA pipes revs to 12000 rpm and worked much better than STD, but Sugaya better at 9500 rpm.

But most interesting difference was between Honda RS and Aprilia RSA pipes: with Honda pipe, was always strong kick from 10000 rpm and this was main difference. Aprilia RSA pipe feels very linear, without any escapades, something nice is in it . I did not notice any difference on max power.
And the same story repeated, when tests these pipes on Suzuki RGV 250 !!! (very different from NS 250).

For 125 and 250 reed engines Honda type maybe more appropriate, but would be very interesting to try Aprilia RSA pipe on 4 cylinder 500 reed type engine.

Of course many other factors exists, but these very simple test just for fun.

[Vannik]

Hi Frits

Exhaust width smaller and transfer time area from 132 to 128 give's more power in sim

335037

How a sim handles blowdown and pretty much all porting:

1. A sim does not predict how much of anything you need, it tells you how well what you have will work,

2. It is not a design tool as such, although there is usually some guidance and design aids in the preprocessor that is used to construct the model,

3. A sim calculates all the flows, purities, temperatures, pressures and densities in all the ducts, boxes, plenums, cylinders and crankcases as the crank rotates. It cannot do this in one continuous calculation but it does it in small increments, typically less than 1 crank degree. At each increment it calculates all the open areas of all the ports and the flow through that port during that time step as a function of all the thermodynamic conditions at that time step. It also calculates the flow and pressure wave movement in all the ducts in that time step. Then it sums all the flows in and out of each plenum, cylinder and crankcase to determine the new states in each as the starting value for the next step.

4. At the end of each revolution it calculates the power, torque, delivery ratios etc for that revolution.

So the sim will not tell you if you have to little or too much time.area of anything, it will just predict less power than what you would get if it was correct and it is up to the simulatee to use his knowledge and all the outputs from the sim to figure out what next.

[dutchpower]

Thanks Neels

The change in the sim was more a bout of Frits last sentence

So is that a good sign !!!

[wobbly]

Wow,I have been called alot of things in my time,but not a simulatee.
One thing that many simulatee's dont have a handle on is the effect that Blowdown has on the scavenging pattern.
As Frits correctly states, when the transfers open,there is more residual combustion pressure above the port than there is case pressure below,within the duct.
Thus we have instantaneous back flow,until the pressure delta is reversed.
You can see this effect on screen as a small "bump " in the transfer pressure ratio as they open.
The lesser the Blowdown STA at the test rpm, the bigger the bump at TPO.

This may seem like a very bad thing, in any scenario.
But it gives the tuner the opportunity to change the way the individual transfer pairs affect the "leaning tower " column up the cylinder back wall.
The transfer that opens first,flows last,due to the inertia of the reversed flow,then having to be re accelerated back in the opposite direction - that is out of the port, not inward down the duct.
Thus the bigger the stagger, the longer this open port "time lag " is in effect - and the greater the effect on the scavenging pattern.

Open the A transfer first, and the B transfers will start to flow pretty much as soon as they open,a few degrees later.
This is classic stagger, and it has been shown in practice to widen the effective powerband at the expense of outright peak power.
Reverse stagger as was employed in the Aprilia RSW/A has the B transfer opening first, thus the much more upward pointing lower A ports are flowing well before the higher B's can.
This has a much more positive effect on peak and overev power capability, not only due to the scavenging effect, but also as the B ports were much wider,lifting them gave a huge increase in STA.

Classic stagger is a useful tool in a situation where you dont have a powervalve, and want to generate some useful mid power - as is the case with KZ2 kart engines.

[Frits Overmars]

Wow,I have been called alot of things in my time,but not a simulatee.Cheer up Wob, it could have been worse. Let's be glad he didn't call us simulants :msn-wink:.

[philou]

Aprilia 500 RSW

http://www.kirikoo.net/images/7philou-20180204-233000.jpg

[dutchpower]

Oke Wobble and other simultee

128/126/126 give 0.198 more KW then 130/132/132 ( Cannot make more blowndown is that what happen )

Think need powervalve !!!!

[Vannik]

Cheer up Wob, it could have been worse. Let's be glad he didn't call us simulants :msn-wink:.

Where I work a "simulant" is a block of TNT, the mass of which determines the size of the mine it simulates, so quite an explosive situation.

I am open to a better word that will work as a single and have a plural :eek5:

[EssexNick]

I think stimulants is more appropriate.

[Haufen]

taking the addictive nature of Neels software into account, I'd vote for "the product" and "the user" :)

[Frits Overmars]

taking the addictive nature of Neels software into account, I'd vote for "the product" and "the user" :)
As a Dutchie I can relate to that :D. I don't know about South-Africans though. Maybe we have to keep looking for simulatee-alternatives.
335058

[senso]

This is the assembled ECU
You can get the kit cheaper controls fuel and ignition with data logging.
https://www.diyautotune.com/product/megasquirt-ii-ems-system-smd-pcb3-57-assembled-ecu/

you can also just buy the bare ecu cards
http://megasquirt.info/products/diy-kits/microsquirt/
https://www.megasquirtnz.co.nz/
http://microsquirt.com/viewforum.php?f=31&sid=777bd0a047d3fb23ba2bfaeae1858585


Take a look at rusefi, runs on a STM32 Devboard, the developer is pretty open and talkative, a friend of mine as an on-going 2 stroke injection project using rusefi, and it works, still needs lots of tunning, but it sure works with a cheapo honda 125 TB with injector, a reluctance wheel welded to the flywheel, some random car crank position sensor and he hacked together a TRIAC and cap for the ignition, with an in tank fuel pump from the same honda 4 stroke donor bike, I think it all came from CBR 125 parts from uk ebay, all in all, he spent less than those ready made kits.

[jbiplane]

Take a look at rusefi
My company Aviamechanica Llc created reliable EFI with integrated ignition suited especially for 2-stroke 1-4 cylinders 36...420cc engines. Curcuit board weight 37 grammes and much more reliable than ecotron we used before. At moment tested on 20+ UAV at t range -65...+40C and up to 5000 meters altitudes. The distinct + of our solution is minimal ammount of hoses and wires compare ones used on cars novadays. Most of electronics integrated at the throttle body. Probably we can make cost effective "box" products, but dunno if it would be rational and profitable activity.

[wobbly]

Dutchpower - your engine is now Blowdown limited as the second example had higher Transfer STA, but made less power.
Thus the smaller transfer STA of the first example is not limiting the power, but the Blowdown increase is able to make more.
Using the same duration's for both , would then exhibit the power band bias I explained due to the scavenging regime changes.
Neels code cant handle this type of detail, as the scavenging system is a canned input, as would be the case with any 1 dimensional sim.
I have not actually tried it, but maybe the powerband shape would be affected correctly by changing from the RS125 to the RSA125 scavenging input
when using the same durations
Usually the reverse stagger gives greater overall STA as the B ports are way bigger, but this isnt the case with this port set, so you would only see scavenging differences.

[ief]

Oke Wobble and other simultee

128/126/126 give 0.198 more KW then 130/132/132 ( Cannot make more blowndown is that what happen )

Think need powervalve !!!!

Looks like (!?!) you didn't take into account that the software doesn't warn you when your total port with exceeds the bore circumference.

Perhaps something Neels could fix :)

[Vannik]

Looks like (!?!) you didn't take into account that the software doesn't warn you when your total port with exceeds the bore circumference.

Perhaps something Neels could fix :)

It was removed on request - I can add it again.

[dutchpower]

It fits perfectly according my chief engineer Ief

[ief]

Didn't know that Neels, perhaps make it an on/ off option then? Why was that not wanted if I may ask?

If the cat say's all is good then all is good Duch ;)

(made some assumptions for that statement but wasn't sure you where aware so left it)

[wobbly]

So here is the result of doing the opposite to having a hot exhaust duct.
I drilled thru the holes from the watercooled case, up underneath the Exhaust duct,and moved the main water inlet to the cylinder
from over the Exhaust port, around to the inlet, allowing cold water to flow directly over the transfers.
Simple mod - 1 Hp, and no sign of deto as the datalogger showed under 1.5V
Thankyou Mr Dyno.

[FastFred]

.

Sharn Steadman, Team ESE racer running her aircooled SuzukiGP125 Bucket at the 2018 Leadfoot hill climb.


<iframe width="560" height="315" src="https://www.youtube.com/embed/ZkoB0ROX07Q" frameborder="0" allow="autoplay; encrypted-media" allowfullscreen></iframe>

[F5 Dave]

That's a nice trick Wob not being familiar with the engine still trying to get head around the flow as it was. So perhaps there were two benefits from the change including the cooler transfers?

One can imagine a university experiment with say 6 sectioned areas, 6 water supplies of control able temperature and many runs just for interests sake. With a simulated head attached with combustion. . Nah that gets complex. But bore distortion info would be interesting as a result.

Squish vs combination chamber area separation?

Maybe the optimal combination is not at all practical but it would show the extent of potential gains up for grabs with no gas flow changes.
Pennies from heaven sort of stuff.

[wobbly]

The stock KZ10C engine has all the water flow into the cylinder from one side directly over the top of the Exhaust duct.
Here is the flow as I did it - see the plug up high on the side of the cylinder.
There are also two small holes drilled right thru to water in the case, that lets cold flow run directly up under the Exhaust duct.

[FastFred]

335082

Car number plate "QIK 125" ...... good one.

[DoldGuy]

Interesting, whether was a small pits after machining and what resistance to cracking?



Maybe this is very old answered question. This particular oversquare engine (57x50,6 mm. rod 109 mm) never work well after 10500 rpm with 50 percentage ( 8,35mm ) squash band. Whatever did nothing changes: gap from 0.7 to 1,2 mm., different combustion shape, different compression different timing and combination all of that . 9 different heads. Bottom and mid good.

All changed with 5 mm squash band. Revs nice from 10500 to 13000 rpm in every combination with diff. compression and shape. Of course mid weaker ( not much from 5000-7000 )

Maybe with different rod length / stroke ratio and piston dia. some correction needed to 50 percentage.


Nuoširdžiai dėkojui jums Fritsai

Also interested in thoughts / opinions on this. I have had similar results but do not have a programmable ignition (yet :msn-wink:)

[DoldGuy]

335082

Car number plate "QIK 125" ...... good one.


+1, Also like the “WobblyPipes”

[wobbly]

The QIK125 plate was given to me by the kids dad,after we won the 125 National Karting Champs 3 in a row.

[SwePatrick]

The stock KZ10C engine has all the water flow into the cylinder from one side directly over the top of the Exhaust duct.
Here is the flow as I did it - see the plug up high on the side of the cylinder.
There are also two small holes drilled right thru to water in the case, that lets cold flow run directly up under the Exhaust duct.

Test if dividing the waterflow before entering cylinder to go both where you put the inlet now and using the old inlet at exhaust aswell.

I´m about to do that myself, but i have a long way before getting there =)

[jamathi]

So here is the result of doing the opposite to having a hot exhaust duct.
I drilled thru the holes from the watercooled case, up underneath the Exhaust duct,and moved the main water inlet to the cylinder
from over the Exhaust port, around to the inlet, allowing cold water to flow directly over the transfers.
Simple mod - 1 Hp, and no sign of deto as the datalogger showed under 1.5V
Thankyou Mr Dyno.

Thank you very much for doing this test.
It confirms my own experience.......
more power and less deto!
My compliments!

[F5 Dave]

The stock KZ10C engine has all the water flow into the cylinder from one side directly over the top of the Exhaust duct.
Here is the flow as I did it - see the plug up high on the side of the cylinder.
There are also two small holes drilled right thru to water in the case, that lets cold flow run directly up under the Exhaust duct.
Case like an old suzuki but with main at rear. So under and over duct important.

[Martin1981]

coating it will likely need new pipe dimensions in my opinion.


Different pipe dimensions wouldn`t be a problem for Wobbly i guess. The test only shows, what Wobbly and Frits told many times.

If the pipe was sucking exhaust gas out of the cylinder only, a coated duct could do something good or at least nothing bad maybe. But there is also fresh charge entering the exhaust duct. And this fresh charge "plug" is later pushed back in the cylinder again by the pipe. And this plug should be well cooled to make the engine make power and not detonate (The same situation as the exhaust gas entering the crankcase by the transfer ports and causing overheating and deto). So the duct should be flown around with water instead of beeing coated. So to speak, the (well cooled) exhaust duct is the intercooler of a 2 stroke engine.

[ken seeber]

So to speak, the (well cooled) exhaust duct is the intercooler of a 2 stroke engine.

Nice analogy.:yes:

[lodgernz]

In all the photos I have seen of disc valve setups, I've only seen one with a trapezoidal shaped inlet port.
Such a shape would seem to offer the least radial angle for a given port area, thereby maximising the fully-open period of the valve.
People who know stuff, like Jan with Aprilia, didn't use this shape so clearly there are issues with it.
Perhaps because the valve would open instantaneously rather than progressively. Closing would still be progressive but rather sudden at the end.
335120

Anyone care to comment?

[TZ350]

335121335122

Suzuki and Kawasaki have both made rotary valve ducts like this.

335123

They become increasingly trapezoidal shaped as you widen them to get more flow area.

Bell or was it Jennings talked about the benefit to wave action of having an abrupt opening/closing. Tried it but not convinced myself, preferred the results I got with a gentler opening/closing and the wear on the closing edge, engine side was less.

[SwePatrick]

In all the photos I have seen of disc valve setups, I've only seen one with a trapezoidal shaped inlet port.
Such a shape would seem to offer the least radial angle for a given port area, thereby maximising the fully-open period of the valve.
People who know stuff, like Jan with Aprilia, didn't use this shape so clearly there are issues with it.
Perhaps because the valve would open instantaneously rather than progressively. Closing would still be progressive but rather sudden at the end.
335120

Anyone care to comment?

I would imagine that in the short inlet tract you don´t want a lot of difference in shapes from the carburetor.
Any altering of the shape robs energy from the atmosphere to fill the crankhouse.

Rgds.

[husaberg]

I would imagine that in the short inlet tract you don´t want a lot of difference in shapes from the carburetor.
Any altering of the shape robs energy from the atmosphere to fill the crankhouse.

Rgds.

The idea behind the rectangular/trapizoid port compared to a true round port is that for the same number of open degrees you gain significantly more time area. ie it is open wider for longer. You achieve similar gains from a larger disc valve. (But with a larger valve you also gain a staighter inlet port as well)
Losing energy? The track needs to change from the carb to the disc port shape regardless.
335124335125335127335128335126
Frits or Jan will explain the rounded corners but i think it was to do with boundary flow.
First pic is RSW125 (2nd 3rd appear to be from a similar year twin ) next one is an older version of Rotax.
The last Frits and Jan can explain the advantages of the shape. But i suspect it opens fully faster for longer time area.
Regardless the intakes clearly worked better with the edges slightly rounded but the port squared off.

[TZ350]

335120


I would imagine that in the short inlet tract you don´t want a lot of difference in shapes from the carburetor.

Maybe True, but achieving it, is not so easy ..... :facepalm:

And maybe not so much of a problem, a short tract may become virtually invisible and it basically becomes a carburettor attached to a window on the side of the crankcase. The carburettor and window have to both be big enough to pass the required amount of air/fuel mixture in the time available and remember the carburettor is open for longer than the window.

[Frits Overmars]

Bell or was it Jennings talked about the benefit to wave action of having an abrupt opening/closing. Tried it but not convinced myself, preferred the results I got with a gentler opening/closing and the wear on the closing edge, engine side was less.You can forget about wave action in the inlet tract. The inlet is open during more crank degrees than the exhaust port, so for a wave to travel up and down the tract once, that tract should be longer than the exhaust pipe (OK, the speed of sound in the inlet tract is lower because it's colder there, but anyway..)
A wave would travel up and down the usual inlet length so often between inlet opening and closure that it would have lost all of its energy by the time the port closes.

You want to open the inlet when there is no pressure difference over the disc. Opening it any earlier would cause pressure loss from the crankcase, and opening it any later would cost time.area and cause an unwelcome drop in crankcase pressure that would slow the transfer flow down.
The only benefit of a late opening is that the pressure difference will send a clearer signal to the carburetter.


I would imagine that in the short inlet tract you don´t want a lot of difference in shapes from the carburetor. Any altering of the shape robs energy from the atmosphere to fill the crankhouse.That's it, Patrick. Any change in shape should be gradual, but you don't want a long inlet tract either, so you must compromise between a trapezoidal shape and a short tract.


The track needs to change from the carb to the disc port shape regardless.Not necessarily, Husa. I'm curious about your view.


The last Frits and Jan can explain the advantages of the shape.I can't; you'd have to ask the Great Leader; he insisted on that 'nose'.

[husaberg]

Not necessarily, Husa. I'm curious about your view.It was the same as yours a compromise over the shortest possible area to blend the shape from the carb bore to the intake port windows greater area.
If you were meaning the rounded corners i would suspect it is the same as having the edges on the ports slightly radiused.
plus square bore carbs are not that common plus a small round intake window in the cases would be bloody restrictive.
335139335140335141

The Kawasaki one (pictured below)actually has back cuts incorporated into the short track, whether this is a production compomise or design feature i am not totally sure.
But it would be nice to suspect its the later.
TZs pic shows these back cuts on the Kawaski 175 valve.
335129335130

I can't; you'd have to ask the Great Leader; he insisted on that 'nose'.
Funny.........

maybe his thoughts were to keep the port open in one area of the port on initail opening?
Or maybe he was a control freak who had been given the keys to the factory soley based on taking the credit for others work efforts at Cagiva?
I did notice the RSA125 has a few totally different discs. but thought that was due to the different orientation of rear disc engine.
335138

[lohring]

Model engine disk valves always have a trapezoidal shape. However, they are confined to the crankcase diameter so need all the area they can get.

Lohring Miller

335131

[SwePatrick]

This is a carb from PVP kart engine.

http://www.pvpkart.com/910%20Back%20side.jpghttp://www.pvpkart.com/910%20Front%20side.jpg

They start to alter the shape already in the carb to make inlettract flow more.
This to gain flow without having a to big area, this gains airspeed that overcomes pressure inside the crankhouse better at the late phase of filling the crankhouse, less 'spitting' backwards.

[lodgernz]

335126

The last Frits and Jan can explain the advantages of the shape. But i suspect it opens fully faster for longer time area.


If I remember correctly, Frits or Jan stated that this disc shape was to give better support to the disc as it passed the port.
But my memory is pretty shit so I'm probably wrong.

[wobbly]

During my time at ZipKart, tuning for Hines Superkart Rotax 250 twin, we tested the rotary valve shape and the port shape to death.
The big issue with the trapezoid port shape is that the inlet column pressure on the disc wore away the closing side of the case really badly, really quickly.
The disc shape with simple opening/closing edges that were angled directly thru the crank center line worked just as well as any other, but the ones we developed
that were like the odd angled Aprilia version, reduced the wear even more with an oval port and lost no power.
We tried concave and convex opening/closing edges as well ( same timings of 140/88 ) with no gains.
I never quite managed to equal the full trapezoid shape power ( slightly better around and after peak ) but we simply could not stop the case wear issue even with
PTFE coatings and lube cutaway slots etc.

[Michael Moore]

Has anyone tried putting a bearing bronze ring around the port opening in the case to try and deal with the wear issue?

With 3D modeling and CNC being relatively easy to come by I'd have thought lofting a surface between the circle profile at the slide and the trapezoid at the case to get a smooth transition would be commonplace.

cheers,
Michael

[Frits Overmars]

Has anyone tried putting a bearing bronze ring around the port opening in the case to try and deal with the wear issue?Sure, and bronze, cast-iron and pertinax disc covers, ceramic coatings, inserted bronze guides like in the picture below, and so on. You name it; it has been tried.
335143


With 3D modeling and CNC being relatively easy to come by I'd have thought lofting a surface between the circle profile at the slide and the trapezoid at the case to get a smooth transition would be commonplace.No matter how smooth you make a transition, if you do it over too short a distance, the transition will become too steep.
For example, you can go from a circle to a trapezoid over a distance of ten times the circle diameter, or you can do it over a distance of one-tenth the diameter.
In both cases it can be smooth, but in the second case it will nevertheless cause a lot of turbulence.

[jamathi]

You can forget about wave action in the inlet tract. The inlet is open during more crank degrees than the exhaust port, so for a wave to travel up and down the tract once, that tract should be longer than the exhaust pipe (OK, the speed of sound in the inlet tract is lower because it's colder there, but anyway..)
A wave would travel up and down the usual inlet length so often between inlet opening and closure that it would have lost all of its energy by the time the port closes.

You want to open the inlet when there is no pressure difference over the disc. Opening it any earlier would cause pressure loss from the crankcase, and opening it any later would cost time.area and cause an unwelcome drop in crankcase pressure that would slow the transfer flow down.
The only benefit of a late opening is that the pressure difference will send a clearer signal to the carburetter.

That's it, Patrick. Any change in shape should be gradual, but you don't want a long inlet tract either, so you must compromise between a trapezoidal shape and a short tract.

Not necessarily, Husa. I'm curious about your view.

I can't; you'd have to ask the Great Leader; he insisted on that 'nose'.

Cutting off that 'nose' made no difference at all when we tried it....

[Jannem]

Calculated the scavenging angles of my cylinder based on information found here and got 22deg A and 10deg B.

However, my piston is old style dome, with approximately 15deg from top piston corner to top of the dome. Should this be taken into account with port angles or just ignored? If accounted for, how much should the port angles be increased?

[Frits Overmars]

Calculated the scavenging angles of my cylinder based on information found here and got 22deg A and 10deg B.
However, my piston is old style dome, with approximately 15deg from top piston corner to top of the dome. Should this be taken into account with port angles or just ignored? If accounted for, how much should the port angles be increased?Hard to say Jannem. The mass flow would probably improve when you give the B-ports that same 15° axial angle, but then you may run the risk that the central scavenging column moves too fast.
Why use that old style piston? Has it anything going for it, or is it carrying a fistful of piston rings, in which case power might be found through reducing ring friction.

[katinas]

Return to Rygerised engine again, this time with almost isolated A, B transfers, just small parts left to do. But first decide to try this on std. engine, if this scheme works.

Today tested NS 250 engine with isolated A and B transfer channels, connected directly to carb through boyssens and isolated from crankcase (like in sketch) and special piston with pockets on sides (add pic), its like imitation Ryger on std. engine. Only C transfer work like normal.
First trying without reeds, but impossible to start from kick and impossible to push bike because winter outside.
With reeds, started easily and revs to 14200 rpm. and then na-na-na-na, feels like rev counter (honda rs 250 ignition 1986) I don't know.
And very interesting thing, when trying std. piston with very low transfers intake timing ( when piston is at TDC, transfers open just at they height) it revs to 12500 rpm. I cant believe. Before test I wish that engine with std. piston revs no more than 7000 rpm.
Can't say anything about power now, but want to try adjustable reed valve block, to understand if this scheme work without reeds at higher revs.

And one similarities with Rygerised engine is that it revs imeadeatly very cleanly without bubbling when engine is cold.

I don't know about Ryger real working principle, but if its in this way, maybe very short con rod on Ryger engine, generated stronger suction signal and faster accelerate fresh mix from carb, through transfer channels when piston close up to TDC.

[Muhr]

So here is the result of doing the opposite to having a hot exhaust duct.
I drilled thru the holes from the watercooled case, up underneath the Exhaust duct,and moved the main water inlet to the cylinder
from over the Exhaust port, around to the inlet, allowing cold water to flow directly over the transfers.
Simple mod - 1 Hp, and no sign of deto as the datalogger showed under 1.5V
Thankyou Mr Dyno.

Good test again!

If we play with the idea that it would only be due to the lower temperature of the mixture, it would mean about 3-4 kw less heat energy transmitted. (If I did not mess up my calc)
Intessant thought

[breezy]

Return to Rygerised engine again, this time with almost isolated A, B transfers, just small parts left to do. But first decide to try this on std. engine, if this scheme works.

Today tested NS 250 engine with isolated A and B transfer channels, connected directly to carb through boyssens and isolated from crankcase (like in sketch) and special piston with pockets on sides (add pic), its like imitation Ryger on std. engine. Only C transfer work like normal.
First trying without reeds, but impossible to start from kick and impossible to push bike because winter outside.
With reeds, started easily and revs to 14200 rpm. and then na-na-na-na, feels like rev counter (honda rs 250 ignition 1986) I don't know.
And very interesting thing, when trying std. piston with very low transfers intake timing ( when piston is at TDC, transfers open just at they height) it revs to 12500 rpm. I cant believe. Before test I wish that engine with std. piston revs no more than 7000 rpm.
Can't say anything about power now, but want to try adjustable reed valve block, to understand if this scheme work without reeds at higher revs.

And one similarities with Rygerised engine is that it revs imeadeatly very cleanly without bubbling when engine is cold.

I don't know about Ryger real working principle, but if its in this way, maybe very short con rod on Ryger engine, generated stronger suction signal and faster accelerate fresh mix from carb, through transfer channels when piston close up to TDC.


So Katinas, your transfer ports a+b are open for almost 360 degrees?

[katinas]

So Katinas, your transfer ports a+b are open for almost 360 degrees?

Transfers and exhaust timing is std. ( aprox Ex 198 trans 132), but suction timing from transfers to crakcase its aprox 220, it depends on how high is cut on piston ( transfers controlled like piston port engine intake window). A B C are open 132 and A B open to crankcase aprox 220.
With std piston suction timing from transfers to crakcase its around 120, I don't measure

[lodgernz]

Calculated the scavenging angles of my cylinder based on information found here and got 22deg A and 10deg B.
However, my piston is old style dome, with approximately 15deg from top piston corner to top of the dome. Should this be taken into account with port angles or just ignored? If accounted for, how much should the port angles be increased?


Hard to say Jannem. The mass flow would probably improve when you give the B-ports that same 15° axial angle, but then you may run the risk that the central scavenging column moves too fast.
Why use that old style piston? Has it anything going for it, or is it carrying a fistful of piston rings, in which case power might be found through reducing ring friction.

I have a related question concerning the "Edge Angle" of the piston dome. I define this as the instantaneous angle at which the dome rises from the notional flat-top measured at the edge of the piston, that is, the angle of the tangent to the dome, at the outer edge of the piston. While this Edge Angle is not the same as the angle discussed above, I wonder how it might affect scavenging patterns.
335155

In my collection of piston "possibles" for my engines, most of which are modern domed racing pistons, every one has an edge angle of 15º or greater. Even a 53mm piston with a mere 3.7mm dome has an edge angle of 15.8º.
Since my B-transfer axial angles will always be considerably less than 15º, I wonder if these pistons will be less than optimal in performance. As the port opens, the designed axial angle of its upper edge will be usurped by the piston edge angle, deflecting the flow upwards at an angle greater than the port axial angle. This will only last a few degrees until the piston moves down far enough for the axial angle to reassert itself, but I wonder if that initial deflection affects scavenging.
Presumably, at least the flow will attach well to cool the piston in the B-port area.

The opposite question arises for the A-transfers: Since the axial angles of these ports will always be greater than 15º, the scavenging flow will not be deflected by the edge angle, but may not have the same attachment to cool the piston.

Clearly it's not a trivial matter to ameliorate these perceived issues, but are they really important? Am I tilting at windmills?

[lodgernz]

In all the photos I have seen of disc valve setups, I've only seen one with a trapezoidal shaped inlet port.
Such a shape would seem to offer the least radial angle for a given port area, thereby maximising the fully-open period of the valve.
People who know stuff, like Jan with Aprilia, didn't use this shape so clearly there are issues with it.
Perhaps because the valve would open instantaneously rather than progressively. Closing would still be progressive but rather sudden at the end.
335120

Anyone care to comment?

Thanks for your contributions guys. A very useful discussion.

[lodgernz]

Return to Rygerised engine again, this time with almost isolated A, B transfers, just small parts left to do. But first decide to try this on std. engine, if this scheme works.

Today tested NS 250 engine with isolated A and B transfer channels, connected directly to carb through boyssens and isolated from crankcase (like in sketch) and special piston with pockets on sides (add pic), its like imitation Ryger on std. engine. Only C transfer work like normal.
First trying without reeds, but impossible to start from kick and impossible to push bike because winter outside.
With reeds, started easily and revs to 14200 rpm. and then na-na-na-na, feels like rev counter (honda rs 250 ignition 1986) I don't know.
And very interesting thing, when trying std. piston with very low transfers intake timing ( when piston is at TDC, transfers open just at they height) it revs to 12500 rpm. I cant believe. Before test I wish that engine with std. piston revs no more than 7000 rpm.
Can't say anything about power now, but want to try adjustable reed valve block, to understand if this scheme work without reeds at higher revs.

And one similarities with Rygerised engine is that it revs imeadeatly very cleanly without bubbling when engine is cold.

I don't know about Ryger real working principle, but if its in this way, maybe very short con rod on Ryger engine, generated stronger suction signal and faster accelerate fresh mix from carb, through transfer channels when piston close up to TDC.

Where do you place the reed valve?

[crbbt]

Big question.

will NX5 cylinders bolt on to later NX4 cases without modification?

[Frits Overmars]

... my piston is old style dome, with approximately 15deg from top piston corner to top of the dome.
I have a related question concerning the "Edge Angle" of the piston dome. I define this as the instantaneous angle at which the dome rises from the notional flat-top measured at the edge of the piston, that is, the angle of the tangent to the dome, at the outer edge of the piston. While this Edge Angle is not the same as the angle discussed above...My definition of the edge angle is the same as yours, Lodgernz. I assumed that Jannem meant the same with his "15deg from top piston corner to top of the dome".
I can't see what else he could have meant.


In my collection of piston "possibles" for my engines, most of which are modern domed racing pistons, every one has an edge angle of 15º or greater. Even a 53mm piston with a mere 3.7mm dome has an edge angle of 15.8º.No engine I worked on in the past three decades had a 15° edge angle. Most pistons were between 7° and 12°; the highest value I found was 13° (in a Suzuki T500).
To ascertain that we both use the same approach, I took your 53 mm bore, 3,7 mm dome height, 15,8° edge radius and it checked out OK (with a 97 mm dome radius).


Since my B-transfer axial angles will always be considerably less than 15º, I wonder if these pistons will be less than optimal in performance.As I wrote in my answer #28610 to Jannem, the optimum performance of the B-ports does not soleley depend on mass flow: http://www.kiwibiker.co.nz/forums/showthread.php/86554-ESE-s-works-engine-tuner?p=1130452977#post1130452977


As the port opens, the designed axial angle of its upper edge will be usurped by the piston edge angle, deflecting the flow upwards at an angle greater than the port axial angle. This will only last a few degrees until the piston moves down far enough for the axial angle to reassert itself, but I wonder if that initial deflection affects scavenging.It's not just that initial reflection; a high piston dome limits the cross flow area much like the axial angle of a transfer roof does.
335164

[jasonu]

Big question.

will NX5 cylinders bolt on to later NX4 cases with modification?

You can bolt anything to anything. Depends on the amount of faffing around you want to do.

[crbbt]

You can bolt anything to anything. Depends on the amount of faffing around you want to do.

whoops! i was meant to say without modification :brick:

[jasonu]

whoops! i was meant to say without modification :brick:

Then hell no!!!!!!

[Matt@TYGA]

Just thought that I'd share this....
The NSR150 has a rather short exhaust duct according to Wobbly's explanation of what's needed. So I've modeled and adapter up that bolts to the exhaust duct exit to lengthen the duct to 1.5*bore and as and when I have time I'll CNC something up and give it a try.

3D printed out a sample last night for a test fit. Seems ok.

I've done a couple of models of different "effective diameters" @ 1.5*bore, so it'll be interesting to see what happens on the dyno.

Also took the theory of cooling the duct and added a water passage. This'll mean mods to the std cylinder to allow water to get into the adapter. I'm temptered just to add a couple of spigots to it for now and just flow water through it. Saves me a bit of work for first test ;)

I'll also have to adjust the pipe to compensate for the longer duct, but that hopefully shouldn't be a task. But if I just change the header length (minus the additional length of duct), without any other changes, that'll give me a 4 degree included angle header. Any comments on this?

Anyway, here's a couple of pics.

I'll let you know what happens.

Matt.

[Jannem]

My definition of the edge angle is the same as yours, Lodgernz. I assumed that Jannem meant the same with his "15deg from top piston corner to top of the dome".
I can't see what else he could have meant.

No engine I worked on in the past three decades had a 15° edge angle. Most pistons were between 7° and 12°; the highest value I found was 13° (in a Suzuki T500).
To ascertain that we both use the same approach, I took your 53 mm bore, 3,7 mm dome height, 15,8° edge radius and it checked out OK (with a 97 mm dome radius).

As I wrote in my post #28610 to Jannem, the optimum performance of the B-ports does not soleley depend on mass flow.

It's not just that initial reflection; a high piston dome like in the picture below limits the cross flow area much like the axial angle of a transfer roof does.
335156

The edge angle of the piston I have is more than 15deg. Would need to check. So, I meant the angle between piston top corner and the tip of the top. Because the shape is rounded the tangent at the piston corner is more. The dome begins ~1mm towards the center from the piston corner.

The raising column speed is definitely something that didn't even cross my mind. As the lower speed translates to higher pressure, I can see how that would be better for less mixing of the fresh charge and exhaust.

I would also think that the higher dome not only shifts the direction of the transfer flow upwards, but also makes the jet flatter forcing it go around the dome and begin the pressure recovery sooner than what would happen with the free jet. How much flow losses this would cause is hard to say, as the directional change does not happen in the duct and more gradual pressure recovery may also be a good thing from the flow perspective, but it probably messes up the designed scavenging pattern. Considering higher surface area of the combustion chamber with the dome and painstakingly designed scavenging for a lower dome piston, it's predictable that the end result has to be worse.

I've struggled to find a good piston with the right compression height for the 44mm bore. Now I have another bottom end, where I could use 5mm longer rod and that would allow using kx60 piston. My cylinder, however, is cast iron and I'm a bit concerned if the ring(s) meant for nikasil would cause me problems. As the piston is such a stressed part and elemental for the performance, I think I need to find a better solution.

The current B-port angle is 15deg before grinding, so I could relatively easily test it with the stock bottom end, then grind and re-test to see the impact with the current piston.

[dutchpower]

Dutchpower - your engine is now Blowdown limited as the second example had higher Transfer STA, but made less power.
Thus the smaller transfer STA of the first example is not limiting the power, but the Blowdown increase is able to make more.
Using the same duration's for both , would then exhibit the power band bias I explained due to the scavenging regime changes.
Neels code cant handle this type of detail, as the scavenging system is a canned input, as would be the case with any 1 dimensional sim.
I have not actually tried it, but maybe the powerband shape would be affected correctly by changing from the RS125 to the RSA125 scavenging input
when using the same durations
Usually the reverse stagger gives greater overall STA as the B ports are way bigger, but this isnt the case with this port set, so you would only see scavenging differences.

This is the difference Wobbly

[teriks]

Return to Rygerised engine again, this time with almost isolated A, B transfers, just small parts left to do. But first decide to try this on std. engine, if this scheme works.

Today tested NS 250 engine with isolated A and B transfer channels, connected directly to carb through boyssens and isolated from crankcase (like in sketch) and special piston with pockets on sides (add pic), its like imitation Ryger on std. engine. Only C transfer work like normal.
First trying without reeds, but impossible to start from kick and impossible to push bike because winter outside.
With reeds, started easily and revs to 14200 rpm. and then na-na-na-na, feels like rev counter (honda rs 250 ignition 1986) I don't know.
And very interesting thing, when trying std. piston with very low transfers intake timing ( when piston is at TDC, transfers open just at they height) it revs to 12500 rpm. I cant believe. Before test I wish that engine with std. piston revs no more than 7000 rpm.
Can't say anything about power now, but want to try adjustable reed valve block, to understand if this scheme work without reeds at higher revs.

And one similarities with Rygerised engine is that it revs imeadeatly very cleanly without bubbling when engine is cold.

I don't know about Ryger real working principle, but if its in this way, maybe very short con rod on Ryger engine, generated stronger suction signal and faster accelerate fresh mix from carb, through transfer channels when piston close up to TDC.
You need to get studded tyres or a dyno, really interested hearing how this goes.

[SwePatrick]

Just thought that I'd share this....


I'll let you know what happens.

Matt.


Yes please, I have about the same idea, to weld a waterjacket at the first 10-15cm of the header on the pipe.

If you´re project is showing promising results i can´t resist build it =)

Rgds.

[husaberg]

whoops! i was meant to say without modification :brick:

http://www.tz250.com/forums/showthread.php?8958-NF4-with-JHA-A-kit-cylinder



There was a major cylinder change at 1997 I think and the stud spacing will not allow newer cylinders on the older 1995-1997 bikes (I think).
but it can be made to fit rather easily it seems. see link above.
But you might be far better off with a 04 PV CR125 cylinder.



All the CR ignitions from about 2002 onward are 12v to drive DC ignitions and powerjets ,TPS and powervalves ( 04 ) so these will bolt

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

Yep, it would be impossible to compete against an engine that had the same power at 13800 as a well tuned stocker has at 12200.

As i say, the CR cylinder is well capable of being tuned to even above this level, is cheap and available.
Add a long 110 rod from say Samarin with a plate and you have what won the last 250GP championship.
Slap on an Ignitech, a modern fat pipe, a VF2 and you are well into the 50Hp zone cheaply with ease..

Are you able to comment on the CR125 cranks and how they'd take the abuse in a road racer vs MX bike Wob? The service interval on the NX4 crank is 2,000 kms, how would they compare.
It'd be a fun exercise to build a NX4 into a superlite/F3 class beating 2 stroke with an engine you described Wobbly!
:ar15:


Is the famous Kiwi ingenuity is dead then? In superkarts here in Australia a friend of mine pioneered several things that are now

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



But as a side point we get 41.5 Hp at the sprocket from a 2002 CR125 dead stock except for the reeds and the pipe for SKUSA racing, throw on a 2004 cylinder with cable PV,do some porting
and your RS125 will get blown away easy.
A complete SKUSA engine parts kit is still available from HRC for under 2000 USD,and I bought a siezed 2004 cylinder,to fit on an old NSR250 MC21, here in NZ
the other day for $200, they are available new on line for around 400USD complete.
The CR125 may be wet clutch, but fit Hinson alloy/kevlar plates and you would never know, and they last forever.
Cheap as chips the whole thing.


The CR125 crank parts are same same as RS125 quality wise and last forever over 12,000 rpm in a SKUSA engine.

I think Lozza has looked at putting a HotRods CR125 crank into the RS as it has higher inertia, and revs on better ?

[katinas]

Where do you place the reed valve?

Testing on original cylinder in simplest way, just add profiled sleeve on cylinder to isolate crankcase , blocked intake windows and increased boyesens. A and B sum area equal to 31 mm dia.
Much better, would be made straight transfer ducts on both sides of cylinder with two carb, but cutting, welding and so on need more time.
And eventually, maybe its just revs without power.

[katinas]

Thank you Husa for this RS/CR collection

[Flettner]

Testing on original cylinder in simplest way, just add profiled sleeve on cylinder to isolate crankcase , blocked intake windows and increased boyesens. A and B sum area equal to 31 mm dia.
Much better, would be made straight transfer ducts on both sides of cylinder with two carb, but cutting, welding and so on need more time.
And eventually, maybe its just revs without power.

we will all be watching,, keen to see how this pans out
I have a similar cylinder on the bench, but uses injection.

[crbbt]

Thanks Husa

always on the hunt for a cheap 04 125. ended up getting a 05 250 instead :woohoo:

be interesting to see if anything lines up on the nx5 cylinder. lucky I have some scrap cases to play with

[husaberg]

Thanks Husa

always on the hunt for a cheap 04 125. ended up getting a 05 250 instead :woohoo:

be interesting to see if anything lines up on the nx5 cylinder. lucky I have some scrap cases to play with
335180335176335177335178335179335181

If you want to beat NX4 with a NF4 try a 2004 cr125 cylinder with a PV. If you get out of the corners quicker you will beat them around the track.
Jerry Burgess and Doohan then Rossi did this for years.
Pray on the weak points of a NX4 rather tha try to replicate one.
Get yourself a decent carb
if moneys tight.A Keihin PWK38S (short body w/Power Jet)
of a KX250 the electric solenoid and tps arround 2001.

throw in a decent pipe and a VF3 Reed valve and a short intake
Spend the rest of some decent suspension.


https://www.tapatalk.com/groups/nsr250/tuckerbag-s-2004-nsr250-using-2004-cr125-barrels-t414.html


Ask Wobbly about the rest he has given out the details on how to mod the mx carb.

[katinas]

we will all be watching,, keen to see how this pans out
I have a similar cylinder on the bench, but uses injection.

Interesting how wind is blowing in A B C tunnels with this scheme.
When piston moves up, is more or less clear. But what happening on down stroke. Maybe at low and mid revs some gas return to A B tunnels and build up pressure and when windows open, pressure help for scavenging. At high revs, maybe wind blows in one way with help from exhaust diffuser and what's happening in C.
Maybe, with isolated bottom, piston not cooled well and for big end needed additional oil. But fresh gas is less contact with hot parts.
Interesting how transfer duration and size influence this type engine performance and what kind exhaust is needed ( Tested without exhaust, just with ex header, and revs easily, but can't say how much, because very strange, Koso tachometer not working with this huge sound in closed area, can't understand ).

Will try to film outside.

[katinas]

In 2002 or 2003 Honda on Cr 125 use biggest reed cage with smallest 28 mm insert, but carb is 38 mm.
2004 they return to std. smaller six reed cage type and normal insert. Maybe with big reed cage they lost speed in midrange and try compensate with smaller insert.
Very interesting, maybe someone know about this and had experience with that time Honda Cr 125 engine

[_____]

[
Get yourself a decent carb
if moneys tight.A Keihin PWK38S (short body w/Power Jet)
[COLOR=#ffffff][FONT=Verdana]of a KX250 the electric solenoid and tps arround 2001.
[COLOR=#ffffff][FONT=Verdana]Ask Wobbly about the rest he has given out the details on how to mod the mx carb.


+1 on that topic!

[husaberg]

In 2002 or 2003 Honda on Cr 125 use biggest reed cage with smallest 28 mm insert, but carb is 38 mm.
2004 they return to std. smaller six reed cage type and normal insert. Maybe with big reed cage they lost speed in midrange and try compensate with smaller insert.
Very interesting, maybe someone know about this and had experience with that time Honda Cr 125 engine
No idea but this covers some of the changes
http://www.eric-gorr.com/files/pdfs/model_tuning_tips_honda_cr.pdf



One big issue with all the MX engines is that the carb is severely angled ( in both planes ) and this gives hugely asymmetric flow thru the petals.

Thus technically the reed blocks are way too big, but due to this flow limitation,in reality the situation is very complex.
I can pick up 4 Hp ( in 36 ) from a SKUSA CR125 simply by changing the petals and backups, to help even out the flow pattern into the case.
If we were allowed a straight manifold off say the RS125, then another 2 Hp is gained instantly,then another 2 with petals to suit that setup.
So going from 36Hp to 40 then to 44 just by changing the petals and manifold.


Romeau, what you are showing will never work.

The whole idea is to reduce the duct volume, so to have a round duct, that then reduces is backwards thinking.
The best RS125 cylinder I have tested had a 32 by 41mm oval shape at the cylinder duct exit.
This then transitioned from that oval to a 41mm header entry.
38mm is plenty for any RS125 cylinder,as I can get 48.8 Hp ( sprocket ) from a TM with a 30mm carb.
The very best RS125 dyno I have seen was 47 HP - rear wheel, this being a PV factory setup as used by Itoh.
That had a stock 38mm SPJ carb, and that translates to close to 50 Hp sprocket.
The reeds in a RS125 are nowhere near as clever as those we use in the TM kart engine,I suggest you start looking there.


Thanks Frits.

This spillover flow out the sides is very apparent when using the style of stuffer as is used in KZ engines.
I discovered this when velocity testing the flow of the SKUSA CR125 reed cage.
As the carb is offset upwards and also angled to the side there is a huge amount of extra flow on the right side petal exits.
There is a higher velocity out sideways than directly in line.
I adjusted the petal backup stiffeners to even out the differences, and picked up over 2 Hp thru nearly the whole powerband.
The only other comment I would have is that a big taper out into the transfer ducts as is shown in the RH pic does not seem to work.
Keeping the area in front of the reed box as small as is possible ( by reducing especially the vertical height ) seems to be better.
I think that making a real effort to fill in the roof and floor, then making extra area to the sides, to help the angled reed cage flow would be the go.
But in KZ we cant add material.

[EssexNick]

No problems for me. I'm viewing white text on a black background. Maybe try highlighting the text.

[Frits Overmars]

No idea but this covers some of the changes
http://www.eric-gorr.com/files/pdfs/model_tuning_tips_honda_cr.pdf







Husa, lately the quotes in your posts on the Kiwibiker and Oddbal forums are almost illegible:
335193335194335195
Funny thing: there's nothing wrong with your posts on the Bucket-Foundry forum.

[Grumph]

No problem with Husa's quotes here, Frits - but your text has faded....

Who's been doing programme updates...

[husaberg]

Husa, lately the quotes in your posts on the Kiwibiker and Oddbal forums are almost illegible:
335193335194335195
Funny thing: there's nothing wrong with your posts on the Bucket-Foundry forum.
Frits you need to cross to the dark side.
Bottom right of page you are currently set to light universe.
I have no idea why its doing it but i have noticed as well esp with multiquotes.
There is a quote above at the top of the page that includes a text and font code that is not in my origional quote?

[katinas]

Filming today
https://www.youtube.com/watch?v=5hOrPZ5AEgc

[Lbracing]

Hi everyone !

First of , you guys really do some amazing work and post incredible quality content , thank you for that .

Second , I have been making my own cylinder from billet for a while but its very time consuming so I want to get some cast ( 10 cylinders ) .
I am looking for someone with the ability to cast them , I can get away with the machining . Any help on this would be very appreciated !

These cylinders are 140cc with rsa style transfers ans exhaust without any cooling system ( run time of under 5 second for chainsaw racing) .

[Norman]

Hi everyone !

First of , you guys really do some amazing work and post incredible quality content , thank you for that .

Second , I have been making my own cylinder from billet for a while but its very time consuming so I want to get some cast ( 10 cylinders ) .
I am looking for someone with the ability to cast them , I can get away with the machining . Any help on this would be very appreciated !

These cylinders are 140cc with rsa style transfers ans exhaust without any cooling system ( run time of under 5 second for chainsaw racing) .


You can check out the company www.formkon.dk. They have for one of their customers casted such type cylinders ("rsa copies") using plastercasting (hm, is that the name for it?). I have been in contact with them for other things but I had the chance to look at one of them cylinders and it looked very good! On their homepage you can find a picture. It was not that expensive as I remember, you can always ask for a qoute.

[wobbly]

Formkon cast the cylinders for PVP Superkart 250cc twin engines direct off the CAD files - very good quality.

[Muhr]

You can check out the company www.formkon.dk. They have for one of their customers casted such type cylinders ("rsa copies") using plastercasting (hm, is that the name for it?). I have been in contact with them for other things but I had the chance to look at one of them cylinders and it looked very good! On their homepage you can find a picture. It was not that expensive as I remember, you can always ask for a qoute.

They are very helpful!
Nothing seemed to be a problem.

[2T Institute]

http://www.tz250.com/forums/showthread.php?8958-NF4-with-JHA-A-kit-cylinder



but it can be made to fit rather easily it seems. see link above.
But you might be far better off with a 04 PV CR125 cylinder.











the result

[breezy]

Filming today
https://www.youtube.com/watch?v=5hOrPZ5AEgc

will be very interesting if this engine, you must give it a name..., does the same under load. im still not quite sure how the set up is even with pictures. is the crankcase still isolated from the cylinder barrel?

[Muhr]

Soon I hope all simulation work will be done! Waiting for cylinder deformation on heating and tightened cylinder head.:wait:

Not the best look, but hope it works

Engine for dyno testing the cylinder:eek5:

[SwePatrick]

Engine for dyno testing the cylinder:eek5:

If i had free hands to alter some small things.
This is from my mind only, no calculations at all. =)
Look carefully, there are a couple of changes.

335217

[Muhr]

If i had free hands to alter some small things.
This is from my mind only, no calculations at all. =)
Look carefully, there are a couple of changes.

335217

The v twin that I'm testing for will inevitably have longer intake to cylinder A. I also do not want to challenge foaming at this moment.
But yes it may be batter with a sorter intake.

[Frits Overmars]

If i had free hands to alter some small things....I like your version Patrick. But why did you alter the lower part of the inner transfer duct curvatures?
335218

[wobbly]

Two quick changes I would go with.
Get rid of the steps in the spigot, and the exit should match the header entry = Effective area of Ex ports total.
Water cool inside the transfer inner walls.

[SwePatrick]

I must say your version looks better Patrick. But why did you change the lower part of the inner transfer duct radius?

This is by experiance from 4stroke tuning, as i stated before one should be careful with to much taper in runners.
And, i have actually made good experiance from a small radius at the beginning of runners that are sitting in a pressurised enviroment.
Look at the runners in an Pro-stock V8(dragracing)
HUGE runners, but small radiouses.
These engines are making HUGE power per litre and the inlet manifold has actually a small pressure inside when in powerband.(ram effect)

Edit: ahh,, now your originalpost made it into this one =)
These prostock engines spit out about 1500-1600hp and has 8liters of displacement, if cylinders only fired every rotation they would be really really cool ;)
A taper of 7 degrees is about maximum from my experiance.

335219

[Muhr]

Two quick changes I would go with.
Get rid of the steps in the spigot, and the exit should match the header entry = Effective area of Ex ports total.
Water cool inside the transfer inner walls.


Tanks for the comments

I didn't get exactly how you ment.

The first 3mm is four machining.

I will take a lock at the transfer cooling.:niceone:

[Haufen]

Look at the runners in an Pro-stock V8(dragracing)
HUGE runners, but small radiouses.
These engines are making HUGE power per litre and the inlet manifold has actually a small pressure inside when in powerband.(ram effect)

These prostock engines spit out about 1500-1600hp and has 8liters of displacement

200 hp per liter is only half way to a decent two-stroke, Patrick :scooter:

So these engines are n/a engines and part of their power is due to intake resonance tuning?

[SwePatrick]

200 hp per liter is only half way to a decent two-stroke, Patrick :scooter:

So these engines are n/a engines and part of their power is due to intake resonance tuning?

Yes, they have a plenum that becoming pressurised a little bit due to 'rejecting air mass' (RAM)
This is so important in those engines that they have some really weird setup on the engines bottom end, rod/stroke ratio at 1.5-1, so the deckheight of the engineblock doesn´t get to high, if getting to high the heads come more apart and thereby destroys the tune in the inletsystem.
They rev these engines ~10000.

Think about all this development gone into an twostroke 8 litre V8 that revs the same.
Could we say about 3500hp?(less frictionlosses due to less moving parts) :msn-wink:

[wobbly]

Muhr, remodel the back face of the spigot such that it matches the cylinder, no steps.
And the exit of the spigot should be the same diameter as the header entrance.

[Muhr]

Muhr, remodel the back face of the spigot such that it matches the cylinder, no steps.
And the exit of the spigot should be the same diameter as the header entrance.

Ok got it! like a k9c

I saw some pictures on the RSA cylinder that made me interested in testing.

[Haufen]

Yes, they have a plenum that becoming pressurised a little bit due to 'rejecting air mass' (RAM)
This is so important in those engines that they have some really weird setup on the engines bottom end, rod/stroke ratio at 1.5-1, so the deckheight of the engineblock doesn´t get to high, if getting to high the heads come more apart and thereby destroys the tune in the inletsystem.
They rev these engines ~10000.

Think about all this development gone into an twostroke 8 litre V8 that revs the same.
Could we say about 3500hp?(less frictionlosses due to less moving parts) :msn-wink:

Then maybe they don't have a bigger radius because this would move the effective resonance point out of ideal tune. And getting ideal distance and big bellmouthes is not possible because of space / design limitations etc. (or maybe just because nobody has tried yet). There are several papers out there describing the ideal bellmouth shape. And a small radius is not what one would look out for in this occasion.

these are fully grown bellmouthes for example
n/a F1 engine on dyno (https://www.youtube.com/watch?v=y2iBbwocYZw)

(they really should make such videos for two-stroke people, too)

I like your idea about the V8 2S engine, although you'd probably have to throw in a couple more cylinders without supercharging to achieve these 3500 hp.

I think Muhr could increase the radius from the entry to the bore face. Seems to be quite small at the moment - if there is one. And as he is designing the cases by himself, he might be able to place the discvalve accordingly to allow for an ideal inlet tract length.

[katinas]

will be very interesting if this engine, you must give it a name..., does the same under load. im still not quite sure how the set up is even with pictures. is the crankcase still isolated from the cylinder barrel?

Under load.....I don't know, but like practice show, static tests like this, does not mean anything. For me, it was interesting to see, if that type scheme can work.
Now quickly pictured sketch on paper, maybe would be more simple to explain.

Yesterday video made with 1 scheme and Spec piston. Transfers ducts, from reed to A and B windows, is isolated from crankcase. C is isolated from reed and work like std transfer. So fresh mix flow to trans windows not from crankcase, but directly from carb. When piston moves up, A, B opens under piston, suction signal goes to carb and fresh mix flow in duct and some part fall in crankcase. What happening when piston moves down, actually is not clear, but maybe hotter fresh mix, return through A and B to trans duct, mix with cooler fresh gas mix from carb and when piston close A B on down stroke, this isolated space became like pressure chamber. When A B opens this pressure help to scavenge and C work in normal way. This is only considerations.

Even yesterday I was thinking that C placed in this way can help to start, bottom and mid. But last night I did not sleep, thinking about C.

Today change to 2 scheme. But first try Std piston. And was again very surprised. Revs to aprox 13500 rpm. with such short suction time.
https://www.youtube.com/watch?v=Qp_cDp3WQI8
When Std piston is at TDC, A and B opens just just ( attach image). And all suction is coming in a very short time, through the such small area. Maybe exhaust doing job but..... with Std piston, succeeded to start engine without reeds. Revs to 12000 rpm, but in a very very lazy way, not like on normal scavenge engine at hi revs without reeds. Strange why exhaust not help. Maybe reeds very important to this scheme.
With 2 scheme at BDC all gas under piston is pressurized and no way to go out. Its like spring under piston and maybe that helps much more than C in 1 scheme.

Tomorrow will try 2 scheme with Spec piston

[Muhr]

I think Muhr could increase the radius from the entry to the bore face. Seems to be quite small at the moment - if there is one. And as he is designing the cases by himself, he might be able to place the discvalve accordingly to allow for an ideal inlet tract length.



You are right there is no radios at the moment (was a bitch to lay something with the geometry the program can't work out)
Do you have any thoughts on ideal inlet tract length?:drinknsin (the problem with the V-twin engine is the cylinder offset of 21mm)

[jonny quest]

335180335176335177335178335179335181

If you want to beat NX4 with a NF4 try a 2004 cr125 cylinder with a PV. If you get out of the corners quicker you will beat them around the track.
Jerry Burgess and Doohan then Rossi did this for years.
Pray on the weak points of a NX4 rather tha try to replicate one.
Get yourself a decent carb
if moneys tight.A Keihin PWK38S (short body w/Power Jet)
of a KX250 the electric solenoid and tps arround 2001.

throw in a decent pipe and a VF3 Reed valve and a short intake
Spend the rest of some decent suspension.


https://www.tapatalk.com/groups/nsr250/tuckerbag-s-2004-nsr250-using-2004-cr125-barrels-t414.html


Ask Wobbly about the rest he has given out the details on how to mod the mx carb.

Curious on what mods are done to the MX carb please

[Vannik]

Look at the runners in an Pro-stock V8(dragracing)
HUGE runners, but small radiouses.
These engines are making HUGE power per litre and the inlet manifold has actually a small pressure inside when in powerband.(ram effect)

The flow conditions are not the same - on the V8 inter-cylinder air stealing is a major issue and one of the reasons for the small radius.

[husaberg]

Curious on what mods are done to the MX carb please
Get rid of the air strikers reprofile it add a bell mouth to mimic the RS125 NX4 SPJ carb
Bend the PJ dohicky up to nearer the top. this is the dohicky in the bell mouth side.
335235
I have the quote onfile from Wob somewhere on a word doc I will dig it up the describes the another mod.


When using a simple powerjet nozzle the tip position matters in that no flow will occur until the slide is well past the exit hole, and there is sufficient airflow

to drag fuel up the feed tube above the bowl level.
With the aftermarket add ons and the ones as used by Lectron you can shorten the dump tube so that the flow will only occur at high slide openings,as well as high air flow.
These also have a built in "lag "control in that it takes time for the fuel to rise up the tube and dump out the exit into the air stream.
With a solenoid controlled setup all this is pretty much irrelevant as the flow can only occur when the solenoid is not powered up, and this
is TPS as well as rpm dependant inside the ECU program..
The carbs as used on the MX bikes has the dump tube very low in the bore as they added and subtracted fuel at low slide positions in those bikes.
For a race engine I bend the tube up to around 1/2 bore, as this is where the exit is on the Kehin SPJ carb for RS125/RS250 Honda.
And the general setting is the solenoid is powered up ie no flow below 4000 and 60% TPS and is powered up again at around 12400 to lean off the mixture and increase revon.
This causes a problem with Ignitechs that are used with only a capacitor, as at startup the solenoid is powered up, dragging all the voltage out of the ECU, so I convert the ECU output
to a 3 step truth table, and have the setting such that below 1500rpm the solenoid isnt powered.


It might pay to bore out the 38mm carb a bit at that stage as well.
I am pretty sure the slide cutaway will need preprofiling for a 125 but the 2001 KX125 one should fit.
I haven't measured the body on the 36mm one. but it might just be the same body as the 38mm.
but someone would have to check. if it is the case it might be better starting with one of those.
I have a 38mm body here I am happy to measure. If someone has the 36mm version.



Here is the bowl of the Solenoid PJ carb, with brass tube added to keep the PJ siphon point underwater at the front.
335233335234

The carbs of the MX bikes with the Powerjet and TPS all have the air guides in the bellmouth in front of the slide.

This kills a heap of flow compared to an SPJ, but does give good response down low ( worth a couple of Hp on a RS125 in the top end for example ).
The flow thing isnt really an issue for a bucket motor as they are only made in 36 and 38mm - so plenty big enough to get the flow back with area.
The SPJ will handle more downdraft due to the Powerjet fuel pickup point in the bowl.
The MX ones have an issue with this as the suction point is right at the back of the bowl and would not be under water if tipped up too far.
I posted a pic of the fix a while ago.

I have no idea why its splitting up wobs quotes but it will not edit it out.

[husaberg]

the result
Some more details Lozza

[Muhr]

Water cool inside the transfer inner walls.

Something like that?!

We'll see what the caster says...

[Muhr]

Something like that?!

We'll see what the caster says...

one more view.

[Haufen]

Do you have any thoughts on ideal inlet tract length?:drinknsin (the problem with the V-twin engine is the cylinder offset of 21mm)

I'd propose the following approach:
Use whatever value the sim tells you as a baseline. (you're a "user of the product", are you?)
From that baseline, allow for 15-20mm of length change in both directions.

This will allow you to validate the sim on the dyno and make adjustments if you choose to change the peak performance rpm in the future, for example. I am using laser cut spacers between the cases and the carb rubber on one of my engines for example.

[Frits Overmars]

I have no idea why its splitting up wobs quotes but it will not edit it out.While you're investigating the problem, could you also do something about the white text on an almost-white background in your quotes, Husa?
I'm having this problem with your posts only, and I'd rather not switch to the 'The Dark Zone', but I don't want to miss part of your contributions either :rolleyes:.

[SwePatrick]

The flow conditions are not the same - on the V8 inter-cylinder air stealing is a major issue and one of the reasons for the small radius.

But still, the divider between A-port and B-port on RSA/RSW cylinders also have quite small radius.

[SwePatrick]

Then maybe they don't have a bigger radius because this would move the effective resonance point out of ideal tune. And getting ideal distance and big bellmouthes is not possible because of space / design limitations etc. (or maybe just because nobody has tried yet). There are several papers out there describing the ideal bellmouth shape. And a small radius is not what one would look out for in this occasion.

these are fully grown bellmouthes for example
n/a F1 engine on dyno (https://www.youtube.com/watch?v=y2iBbwocYZw)

(they really should make such videos for two-stroke people, too)

I like your idea about the V8 2S engine, although you'd probably have to throw in a couple more cylinders without supercharging to achieve these 3500 hp.

I think Muhr could increase the radius from the entry to the bore face. Seems to be quite small at the moment - if there is one. And as he is designing the cases by himself, he might be able to place the discvalve accordingly to allow for an ideal inlet tract length.

At the lip of the velocitystacks the radius is quite small. ;)

[SwePatrick]

You are right there is no radios at the moment (was a bitch to lay something with the geometry the program can't work out)
Do you have any thoughts on ideal inlet tract length?:drinknsin (the problem with the V-twin engine is the cylinder offset of 21mm)

Make the discs and the 'lids' the same offset.
Then you should have the same length on them both.

[Muhr]

Make the discs and the 'lids' the same offset.
Then you should have the same length on them both.

Im doing a singel crank engine.

[SwePatrick]

Ohh,, forgot about that.
but still make two length´s on the 'lid' to compensate for the offset.
Then try to shorten everything, in my pic i posted one can place the disc even more close to the crank.
You don´t need any rubberbot for the carb for an example.
Just machine a o-ring groove, then push in the carb, it locks in place on carb´s groove.
Shorten the velocitystack on the carbs.

I actually thinking if too long inlettracts you might stumble into problems at lower rpms and hardcore timings on the disc.
Problems as: very difficult to start as it can become a low frequent helmholzresonator that only spits outwards.
You might have seen that problem before ;)

[Muhr]

Ohh,, forgot about that.
but still make two length´s on the 'lid' to compensate for the offset.
Then try to shorten everything, in my pic i posted one can place the disc even more close to the crank.
You don´t need any rubberbot for the carb for an example.
Just machine a o-ring groove, then push in the carb, it locks in place on carb´s groove.
Shorten the velocitystack on the carbs.

I actually thinking if too long inlettracts you might stumble into problems at lower rpms and hardcore timings on the disc.
Problems as: very difficult to start as it can become a low frequent helmholzresonator that only spits outwards.
You might have seen that problem before ;)


Of course, I will try to have the same intake length unless the sacrifices are too big.
As far as carburettors are concerned, I have spent too many hours on foaming to have the energy getting that to work.

:laugh: Yes we have had som problems! in that case it was a unfortunate placement of the intake which made opening and closing times very long(inafficient) and restrictions in possible size and of course hardcore timing

It's too bad that rotary valves do not care about piston speed.

[Muhr]

I'd propose the following approach:
Use whatever value the sim tells you as a baseline. (you're a "user of the product", are you?)
From that baseline, allow for 15-20mm of length change in both directions.

This will allow you to validate the sim on the dyno and make adjustments if you choose to change the peak performance rpm in the future, for example. I am using laser cut spacers between the cases and the carb rubber on one of my engines for example.

Thanks Haufen

Yes i am!(I realist that you most have done your one engine before you die. And my first son is 4 so a better hurry)
I had a thought of making rubber distances and see how long you can get away with.

[jonny quest]

The later year CR125 came with no PJ TMX Mikuni. They do have TPS. So many bag on that TMX. I really like them.

[2T Institute]

Some more details Lozza

Hopefully next round of improvements well see over 50hp, lifts the front in 2nd with no clutch, can win races outright against GP250's.

Main thing is it is tuned to the point of deto each time it hits the track.

[F5 Dave]

Pah!. My 50 has won races against a GP250 with a small gurl riding it. :msn-wink:

I have the picture. He must have felt (and been) a complete wally.

[jamathi]

But still, the divider between A-port and B-port on RSA/RSW cylinders also have quite small radius.

Of course a bigger radius was tried.
The result was less power....

[husaberg]

Hopefully next round of improvements well see over 50hp, lifts the front in 2nd with no clutch, can win races outright against GP250's.

Main thing is it is tuned to the point of deto each time it hits the track.
Details of the spec Lozza cylinder carb pipe etc.

[SwePatrick]

Of course a bigger radius was tried.
The result was less power....

As i suspected, the design you ended up with, was not left unattended before choosing it ;)
And it runs hand in hand with my own experiances.

Programs and flowbenches might say one thing, but real life tells you the real thing =)

[Jannem]

Professionals in this board have shared that the CCR of 1.3 is something to aim for w. developed case reed engines. If you can’t maximize carburetion, will you increase CCR?

[katinas]

Thanks Husa. Indeed Eric Gregor write about Cr 125 2000-2003 midrange weakness and resloved this with V3 reed.

Add yesterday footage

https://www.youtube.com/watch?v=U_3pT-ku99o
https://www.youtube.com/watch?v=munV4DRt9nc

[katinas]

one more view.

Interesting, will you choose Jan"s transfers cooling channel.

[Muhr]

As i suspected, the design you ended up with, was not left unattended before choosing it ;)
And it runs hand in hand with my own experiances.

Programs and flowbenches might say one thing, but real life tells you the real thing =)


On flow sim as I did, a divider with smaller radios makes less "noise" on the flow next to it. but it does not help with velocity which the inner and outer radius of transfers does, I think both of these designs fulfill a task.
But on the other hand, the SX cylinder has a design as you advocates.
What is best I do not know, but what I tried to do is imitate the rsa as far as I could.:drool:

[Muhr]

Interesting, will you choose Jan"s transfers cooling channel.

Thanks

Have not seen that picture before!

My first sketch I had it in but then it has been forgotten a bit but will look at it

[SwePatrick]

On flow sim as I did, a divider with smaller radios makes less "noise" on the flow next to it. but it does not help with velocity which the inner and outer radius of transfers does, I think both of these designs fulfill a task.
But on the other hand, the SX cylinder has a design as you advocates.
What is best I do not know, but what I tried to imitate the rsa as far as I could.:drool:

One should be careful with what programs says in simulations.
They can almost never simulate the pulses correct.
And one need to simulate if doing so, the fact that it isn´t constant flow in the transfers.
It´s more like 'piston builds up pressure' and then it´s like puncturing a ballon when piston opening the transfers, and quickly after that the pipe extends the time the transfers flows and that with less pressureratios.

The faster engine revs the more simularities with constant flow it becomes, but still there is the same function only faster.
Due to air is compressable and tunable with helmholtz one can get very cool features like a shitload of power =)

My new cylinder i experimenting with has increased volume in transfers as i want the 'bulk load' of fresh gas close to the piston ready to be pressed in by crankhousepressure.
But i haven´t increased the footprint against the engineblock.

And by this i also have a question to all.
To securely fill the transfers with fresh load of airmixture when piston is going upwards.
Could it be a good idea to have holes drilled from cylinderliner against the innerradius in transfers?
Just so the piston opens these ones earlier than normal when the cutouts in pistonskirt opens the transfers on the underside.

An old Malossi or Zeta cylinder for Honda MT5 had this idea:
335265

[Jannem]

My new cylinder i experimenting with has increased volume in transfers as i want the 'bulk load' of fresh gas close to the piston ready to be pressed in by crankhousepressure.
But i haven´t increased the footprint against the engineblock.

And by this i also have a question to all.
To securely fill the transfers with fresh load of airmixture when piston is going upwards.
Could it be a good idea to have holes drilled from cylinderliner against the innerradius in transfers?
Just so the piston opens these ones earlier than normal when the cutouts in pistonskirt opens the transfers on the underside.

An old Malossi or Zeta cylinder for Honda MT5 had this idea:
335265

Don't have experience to reply to you exact question, but here's what I intend to try for the same goal:
Keep the transfer volume relatively small and make a radiused outward bulge into the transfer entry in the cases. Puts volume where it needs to be, increases pressure at the entry. It will make the long side of the transfer wall look shorter (more equal length to short side), which should be a good thing, as air is not only compressible, but also elastic fluid.

[koenich]

But on the other hand, the SX cylinder has a design as you advocates.
reg. the 50SX cylinder, in my opinion it always makes sense to keep in mind that it was originally designed for a non-gearbox kids motocross bike and not as a 20+ HP racing cylinder...so in the design are probably some features which the designer wouldn't do for a proper racing cylinder.

[katinas]

Could it be a good idea to have holes drilled from cylinderliner against the innerradius in transfers?
Just so the piston opens these ones earlier than normal when the cutouts in piston skirt opens the transfers on the underside.

An old Malossi or Zeta cylinder for Honda MT5 had this idea:
335265

Very interesting question about cutouts in piston skirt.
Reed and rotary engines works in different way. Zeta MTX is reed valve and this windows can help. But rotary engine exhaust, at the closed inlet condition , can't suck additional fresh mix from carb and this is one of the major difference, that playing on crankcase volume, exhaust, conrod, carb....
When RSA piston (in pic), with very low cutouts, is at TDC, transfers, maybe not open at all ( we need to ask Jan ). Maybe strong fluctuation in transfers is very important on rotary engine with closed crankcase ( more than with reeds) and any holes in the duct, can destroy this nice exhaust-crankcase orchestra.
Interesting, if 125 cc rotary engine with 30 mm carb can reach 47hp like TM.

In addition to this, last year tested piston with deep pockets on sides (add pic ), and when piston moves up transfers open very early, and some part of fresh mix goes directly to trans duct from boyesens. From first ride feels different in comparison with std. piston: from 10500 to 12500 rpm more power, but little less from 8500 to 10500 rpm. Can't remember how many times change these pistons for comparisons and always this piston was a winner. Plus 1000 revs more than with std. piston. But again,this is reed engine, not rotary.

[Jannem]

Very interesting question about cutouts in piston skirt.
Reed and rotary engines works in different way. Zeta MTX is reed valve and this windows can help. But rotary engine exhaust, at the closed inlet condition , can't suck additional fresh mix from carb and this is one of the major difference that playing on crankcase volume, exhaust, conrod, carb....
When RSA piston, with very low cutouts, is at TDC, transfers, maybe not open at all ( we need to ask Jan ). Maybe strong fluctuation in transfers is very important on rotary engine with closed crankcase ( more than with reeds) and any holes in the duct, can destroy this nice exhaust-crankcase orchestra.
Interesting, if 125 cc rotary engine with 30 mm carb can reach 47hp like TM.

Would be also interesting to know where the cutout is located when the transfer begins to open and when it's fully open vs. the cutout in the cylinder.

[Muhr]

Interesting, will you choose Jan"s transfers cooling channel.


This is what I managed to do.

[katinas]

Would be also interesting to know where the cutout is located when the transfer begins to open and when it's fully open vs. the cutout in the cylinder.

Piston, with low cutouts, at BDC masked big part of cylinder bottom cutout and maybe this again work in good way.
Maybe with low cutout piston runs cooler and more masked trans duct help maintain higher density mix in ducts, before trans windows opens. And at very high revs at BDC, more isolated ducts better resist to exhaust gas. But this is only considerations.
Interesting how many times gas fluctuated in trans ducts at different revs, before transfer windows opens: 1/2, 3/2, 5/2.......

[katinas]

This is what I managed to do.

Very nice job, but would be interesting to rise up exhaust bottom, like Jan done.

[Jannem]

Piston, with low cutouts, at BDC masked big part of cylinder bottom cutout and maybe this again work in good way.
Maybe with low cutout piston runs cooler and more masked trans duct help maintain higher density mix in ducts, before trans windows opens. And at very high revs at BDC, more isolated ducts better resist to exhaust gas. But this is only considerations.
Interesting how many times gas fluctuated in trans ducts at different revs, before transfer windows opens: 1/2, 3/2, 5/2.......

Another consideration is that it effectively makes t-port short and long walls more even in length reducing turbulence in addition to changing tuned length.

[Frits Overmars]

Another consideration is that it effectively makes t-port short and long walls more even in length...Jannem, abbreviations can easily lead to misunderstandings. When you mention a T-port, most people think of something like the yellow port below.
335268

[Muhr]

Very nice job, but would be interesting to rise up exhaust bottom, like Jan done.

I thought I'd read that it came up but then went down again?:corn:


Interesting, if 125 cc rotary engine with 30 mm carb can reach 47hp like TM.

I would say no. but I calculate by hand, maybe the guys with programs say different.:dodge:

[Jannem]

Jannem, abbreviations can easily lead to misunderstandings. When you mention a T-port, most people think of something like the yellow port below.
335268

Oops. In that context it must sound like gibberish...
I meant transfer port of course, good catch.

[katinas]

Another consideration is that it effectively makes t-port short and long walls more even in length reducing turbulence in addition to changing tuned length.

Yes, a lot of gradually changing areas: intake window, intake to transfer ducts, transfer windows, exhaust windows plus power valve.

[katinas]

Would be also interesting to know where the cutout is located when the transfer begins to open and when it's fully open vs. the cutout in the cylinder.

You need to know the crank web dia., con rod length ( 115 or 120 mm) on this picture, distance from trans windows upper edge to the top of the cylinder and you can easy calculate it. Measure aprox dimension of this piston.

Quick search through pictures and if crank web dia is around 82 mm, then:
With 115 mm con rod, at TDC, from piston cutaway to crankcase - around 74 mm. so at BDC - around 20 mm.
If transfer windows height 14 mm, then 34 mm before trans opens. But this could be not very accurate.

[Muhr]

This is what I managed to do.

better view :sweatdrop

[Frits Overmars]

.....:niceone:....

[katinas]

O-
.....but what I tried to do is imitate the rsa as far as I could.:drool:

If try continue from where Jan stopped, why not to try exhaust bottom at transfers upper edge level, and then grinding in small steps.
Interesting how bottom exhaust duct shape should look like with this configuration, parallel with upper and oval cross-section or something different,
of course with ......G, H,.......

[Muhr]

If try continue from where Jan stopped, why not to try exhaust bottom at transfers upper edge level, and then grinding in small steps.
Interesting how bottom exhaust duct shape should look like with this configuration, parallel with upper and oval cross-section or something different,
of course with ......G, H,.......

Yes, interesting, is not that a bit of 1/2 what Frits did with FOS cylinder? Or what do you say Frits?
In general, it seems interesting to do more of the processually larger surface area you have in a 50cc. And especially with regard to blowdown.
Tried to find some more info about RSA's blowdown area, without success.

[2T Institute]

Details of the spec Lozza cylinder carb pipe etc.

nf4 cylinder kit hrc spec pipe made from 1.1mm mild steel, zeeltronic ignition total loss. Rest standard nf4.

[Frits Overmars]

Tried to find some more info about RSA's blowdown area, without success.I wrote about it on http://www.pit-lane.biz/ and I think I also posted a couple of links here to that French thread, some time ago, but I don't remember where exactly, so here are those links once again:
http://www.pit-lane.biz/t117p318-gp125-all-that-you-wanted-to-know-on-aprilia-rsa-125-and-more-by-mr-jan-thiel-and-mr-frits-overmars-part-1-locked
http://www.pit-lane.biz/t117p333-gp125-all-that-you-wanted-to-know-on-aprilia-rsa-125-and-more-by-mr-jan-thiel-and-mr-frits-overmars-part-1-locked

[peewee]

hey guys heres a couple updates as the methanol nitro bike is almost ready to run again or fail miserably :wings:. but don't laugh to much since im not a expert welder :laugh:. this is the changes I made during the winter since the last time riding it about four months ago.

lowered com ratio from 16 to 12.5. I didn't install a com release valve in this head because the last one kept blowing up from the nitro. likely a engineering design mistake on my part. I may try a hand held starter on the crankshaft if I have trouble kick starting it

installed a fourth fuel jet

installed a larger float valve

increased float bowl capacity

grinded the needle richer at idle position

made a new fuel tank of much smaller capacity (2.8L vs 13L with original tank). this now allows easy access to the spark plug and relocated the fuel valve so I could eliminate the fuel pump.

next week im going to a local machinist and making a new reducing exh spigot but unfortunately it wont be water cooled.

I still need to determine if the fuel flow is ok but I think it will be since the bowl capacity is quit alot. with just the fuel valve its 2.8L per 45sec. with the inline fuel filter it slows a bit to 2.8L per 75sec. I haven't yet checked the flow rate of the float valve in the carb or what the approximate engine consumption might be

[wobbly]

This is a favorite hobby horse of Ken Seeber and mine.
Why does everyone leave the transfer duct outer walls uncooled.
I have measured the temp of a race engine at the case deck line on the outside with a press in probe, and its over 80*C when the water temp is at 45*C.
Seems so obvious, especially when it is such a mission to cool the inner duct radius.
Here is crude idea to add enclosing covers down to the the split line.
The other thing that is monkey see monkey do is the insert spigot down into the bore.
This means the squish has no cooling from the side,and is miles away from the water above.
Delete the spigot , and allow water in close to this critical area to help prevent spontaneous detonation of the trapped end gases, simply due to the material behind the
inserts squish band maintaining boundary layer coolness.
This is an extension of having the cold water regime flow over the transfers first,next the Exhaust then up into the head and across and out.
My latest dyno result on here show this is superior to any other scenario.

[SwePatrick]

Why does everyone leave the transfer duct outer walls uncooled.
I have measured the temp of a race engine at the case deck line on the outside with a press in probe, and its over 80*C when the water temp is at 45*C.


Yes, i have asked myself the same question.
If i would have run petrol i would have done it without any thought at all :)
Methanol is so superior in keeping things cool that i figure i don´t need it,, yet ;)

[SwePatrick]

Very interesting question about cutouts in piston skirt.
Reed and rotary engines works in different way. Zeta MTX is reed valve and this windows can help. But rotary engine exhaust, at the closed inlet condition , can't suck additional fresh mix from carb and this is one of the major difference, that playing on crankcase volume, exhaust, conrod, carb....
When RSA piston (in pic), with very low cutouts, is at TDC, transfers, maybe not open at all ( we need to ask Jan ). Maybe strong fluctuation in transfers is very important on rotary engine with closed crankcase ( more than with reeds) and any holes in the duct, can destroy this nice exhaust-crankcase orchestra.
Interesting, if 125 cc rotary engine with 30 mm carb can reach 47hp like TM.

In addition to this, last year tested piston with deep pockets on sides (add pic ), and when piston moves up transfers open very early, and some part of fresh mix goes directly to trans duct from boyesens. From first ride feels different in comparison with std. piston: from 10500 to 12500 rpm more power, but little less from 8500 to 10500 rpm. Can't remember how many times change these pistons for comparisons and always this piston was a winner. Plus 1000 revs more than with std. piston. But again,this is reed engine, not rotary.

Interesting experiances =)
As i see a twostrokes crankhouse and transfers: one need to help with every little thing one can do, to help effective filling of the crankhouse.
If completely filled there will be more for piston to pump up above the piston.
Basic rules =)

[SwePatrick]

I like your version Patrick. But why did you alter the lower part of the inner transfer duct curvatures?
335218

Second quote of this post ;)

I forgot to mention, in a curved runner one also want as small length differences as possible on inner radius and outer radius.

[peewee]

If try continue from where Jan stopped, why not to try exhaust bottom at transfers upper edge level, and then grinding in small steps.
Interesting how bottom exhaust duct shape should look like with this configuration, parallel with upper and oval cross-section or something different,
of course with ......G, H,.......

im surprised nobody still has tried it yet ? maybe you can get the answer finally :Punk:. I raised the bottom about 6mm on 82mm stroke but I had no way to test it. I hope it is giving some extra power ! without knowing for sure I didn't want to raise it any further

[Muhr]

This is a favorite hobby horse of Ken Seeber and mine.
Why does everyone leave the transfer duct outer walls uncooled.
I have measured the temp of a race engine at the case deck line on the outside with a press in probe, and its over 80*C when the water temp is at 45*C.
Seems so obvious, especially when it is such a mission to cool the inner duct radius.
Here is crude idea to add enclosing covers down to the the split line.
The other thing that is monkey see monkey do is the insert spigot down into the bore.
This means the squish has no cooling from the side,and is miles away from the water above.
Delete the spigot , and allow water in close to this critical area to help prevent spontaneous detonation of the trapped end gases, simply due to the material behind the
inserts squish band maintaining boundary layer coolness.
This is an extension of having the cold water regime flow over the transfers first,next the Exhaust then up into the head and across and out.
My latest dyno result on here show this is superior to any other scenario.

Thanks for the input!

I like it but not the job that would be required to get it done. draw a new cylinder more or less.:cry:
Yes the insert spigot is a lazy mans job, makes it easy to raise and lower the cylinder head but can definitely make some adjustments there

[TZ350]

im surprised nobody still has tried it yet ?

Exhaust port floor higher than BDC. It has been tried before and the results posted on this thread. Use this search term "floordam site:www.kiwibiker.co.nz (http://www.kiwibiker.co.nz)" to find references to it.


The stuffer plate is held down by screws through the exhaust port floor, the glue is only there to seal it.


The floor of the exhaust port is higher than BDC. I have no idea how high the exhaust port floor should be.


The glued and screwed in port floor dam held up OK and the dyno results were better.

335396

The idea of rasing the exhaust port floor seemed to work and the results were encouraging but the cylinder was ruined by other porting work so that experiment has stalled for now.

[peewee]

i think many people , including myself, have raised the floor to some extent. but ive never seen anyone raise it to the transfer tops. i think this is what katinis is planning to do

[TZ350]

i think many people , including myself, have raised the floor to some extent. but ive never seen anyone raise it to the transfer tops.

Take a look here, a modified Suzuki RG50 engine with the exhaust port floor at TPO. These experiments were previously posted on this thread including dyno graphs of the results.


Blue = Exhaust dam level with TPO. Red = Dam opening 4 deg after TPO.


Exhaust port dam ... Blue = Standard "A" ports, Red = Widened "A" ports. Useful improvement in bottom end power.

Also the 50cc engines single exhaust port was successfully widened out to 85% of bore diameter.

Our results gave us some idea but I think you are right, starting with the exhaust floor at TPO and progressively grinding it down would be a very interesting experiment.

[TZ350]

.

There really is a lot of good information on this thread, making use of Googles "site:" function is a great way to find it all.

Search Term site:www.kiwibiker.co.nz (http://www.kiwibiker.co.nz/)

[Muhr]

I wrote about it on http://www.pit-lane.biz/ and I think I also posted a couple of links here to that French thread, some time ago, but I don't remember where exactly, so here are those links once again:
http://www.pit-lane.biz/t117p318-gp125-all-that-you-wanted-to-know-on-aprilia-rsa-125-and-more-by-mr-jan-thiel-and-mr-frits-overmars-part-1-locked
http://www.pit-lane.biz/t117p333-gp125-all-that-you-wanted-to-know-on-aprilia-rsa-125-and-more-by-mr-jan-thiel-and-mr-frits-overmars-part-1-locked


Thanks Frits very interesting reading no one can blame you for not sharing your experience:niceone:.
Tried to look at the pictures but did not understand the French and what they wanted me to do

[Frits Overmars]

next week im going to a local machinist and making a new reducing exh spigot but unfortunately it wont be water cooled.If you're planning to fit a watercooled spigot eventually, why not make one right away? You've still got a week to make a sketch.


I still need to determine if the fuel flow is ok but I think it will be.... I haven't yet checked the flow rate of the float valve in the carb...You're joking, aren't you Peewee? Please tell me you're joking.
Methanol flow should be 16 cc per hp per minute. That's easy enough to check, but you must flow all relevant parts simultaneously, starting with the tank breather and certainly including the float valve. And if you add nitromethane, the flow requirement increases steeply, depending on the nitro percentage of course.


Thanks Frits very interesting reading no one can blame you for not sharing your experience.
Tried to look at the pictures but did not understand the French and what they wanted me to doThanks for the flowers Muhr.
I hear you about not understanding the French. The lingo I can handle, but the natives sometimes... Anyway, with kind permission of the Pit-Lane forum moderator I'm writing in English there (or at least my version of it).
Oh, wait a minute. Do you mean you can't see the pictures? I guess you'll have to register first. I can't go into that now but it can't be too hard finding a school boy or girl who has sufficient French. Or you could try Google Translator; always good for a laugh.

[jamathi]

Yes, interesting, is not that a bit of 1/2 what Frits did with FOS cylinder? Or what do you say Frits?
In general, it seems interesting to do more of the processually larger surface area you have in a 50cc. And especially with regard to blowdown.
Tried to find some more info about RSA's blowdown area, without success.

I don't really know the RSA's blowdown area, we never calculated such things......
It was made as big as possible, by trial and error.
But we tested a lot at the flow bench!
On most moped engines you are very limited by the cylinder studs.
We were fortunate enough to be able to cast our own cylinders, making our own casting models.

Of course I fully agree with Wobbly about cylinder cooling: The outside of the transfer ducts should be cooled as well.
I am 99,9% sure that this will give more power!!!
My compliments Wobbly!

[JanBros]

The other thing that is monkey see monkey do is the insert spigot down into the bore.
This means the squish has no cooling from the side,and is miles away from the water above.
Delete the spigot , and allow water in close to this critical area to help prevent spontaneous detonation of the trapped end gases, simply due to the material behind the
inserts squish band maintaining boundary layer coolness.


any suggestions as to how thin the wall's of the combustion chamber (above squish/chamber itself) can be made, let's say for a 54mm bore ?

[Muhr]

Thanks for the flowers Muhr.
I hear you about not understanding the French. The lingo I can handle, but the natives sometimes... Anyway, with kind permission of the Pit-Lane forum moderator I'm writing in English there (or at least my version of it).
Oh, wait a minute. Do you mean you can't see the pictures? I guess you'll have to register first. I can't go into that now but it can't be too hard finding a school boy or girl who has sufficient French. Or you could try Google Translator; always good for a laugh.

I'm going to practice my French:yes:

Edit: I finally managed to understand the French!:woohoo:
Thought it would be 40-50mm2 bigger. I have a lot to learn (don't know how the time area distribution looks like)


I don't really know the RSA's blowdown area, we never calculated such things......
It was made as big as possible, by trial and error.
But we tested a lot at the flow bench!
On most moped engines you are very limited by the cylinder studs.
We were fortunate enough to be able to cast our own cylinders, making our own casting models.

Of course I fully agree with Wobbly about cylinder cooling: The outside of the transfer ducts should be cooled as well.
I am 99,9% sure that this will give more power!!!
My compliments Wobbly!

Thanks Jan

In my first attempt with Wobbly's cooling, I've managed to destroy all forms of flow distribution. I hope I can come with a cylinder 1.2 but I will get forced to broaden the cylinder and then new crankcase so hopefully to the 2 cylinder version. The first engine is singel cylinder test.
Then I can also see what tradeoff the longer intake due to wider cylinder will bring if i cant find a solution to the studs.



any suggestions as to how thin the wall's of the combustion chamber (above squish/chamber itself) can be made, let's say for a 54mm bore ?

Do you mean before this happens (picture) that is 2mm 7075 50 bore




Wobbly

Delete the spigot , and allow water in close to this critical area to help prevent spontaneous detonation of the trapped end gases, simply due to the material behind the
inserts squish band maintaining boundary layer coolness.
This is an extension of having the cold water regime flow over the transfers first,next the Exhaust then up into the head and across and out.

Updated cylinder head:innocent:

[tdc211]

Raising the ex floor by the bore a good amount will require different pipe. Correct?
going from 180 degress up to 150 has a big change in delivery in sim ..

[SwePatrick]

Raising the floor doesn´t change the duration ;)

[peewee]

If you're planning to fit a watercooled spigot eventually, why not make one right away? You've still got a week to make a sketch.

You're joking, aren't you Peewee? Please tell me you're joking.
Methanol flow should be 16 cc per hp per minute. That's easy enough to check, but you must flow all relevant parts simultaneously, starting with the tank breather and certainly including the float valve. And if you add nitromethane, the flow requirement increases steeply, depending on the nitro percentage of course.

.

hi frits. I hope you didn't mistake me for some kind of 2t expert :laugh:. its just a part time hobby, so the clearly obvious things aren't always so obvious. I should of welded a shell over the outer exh and transfer passages for water channels. then a water cooled exh spigot could be used. but as of now theres only water around the cyl bore. I did however show a sketch a few pages back of a water cooled spigot that ill use on my other engine since it has water channels around the full exh passage

few months ago I had a idea that may solve any fuel flow problems I might encounter, I still may carry on with this idea. I have a spare float bowl suited for a lectron and it has its own fuel inlet nipple and float valve system. problem is, its mostly meant for a engine with the carb angled out toward the left side like a Honda. my carb angles out to the opposite side, meaning the bowl is to wide and hits the kickstart area of the crankcase. although I had thought of cutting the bowl in half and welding the inlet and float valve setup on the opposite side. with two fuel inlets (one in the carb and one in the bowl) the engine wouldn't be so dependant on the large capacity of the current bowl with single inlet. I didn't want to use the current huge bowl but its picking up the slack of any deficiencies in the current system.

with two 5/16" fuel lines to the carb/bowl im sure it would be very near 7.5L per min flow , since my current single 5/16" line is near exactly 3.7L per min to the carb (without inline fuel filter installed). but how much fuel could pass through the two floats valves , im not sure yet but I plan to test the the carb valve soon. the carb float valve is 3.5mm diam but I cant recall the float valve size in the bowl.

[tdc211]

Raising the floor doesn´t change the duration ;)

Maybe i should of said. Raising the floor at bdc.

[Muhr]

with two 5/16" fuel lines to the carb/bowl im sure it would be very near 7.5L per min flow , since my current single 5/16" line is near exactly 3.7L per min to the carb (without inline fuel filter installed). but how much fuel could pass through the two floats valves , im not sure yet but I plan to test the the carb valve soon. the carb float valve is 3.5mm diam but I cant recall the float valve size in the bowl.

That is serious power

7500/16 or did I miss something

[Jannem]

Anyone experimented with secondary air injection? Tested the bike in original condition with it connected and plugged. Plugged-> higher peak power, operational-> more power after the peak.
It would be simple to make a solenoid switched secondary air injection to heat up the pipe. Could run richer at top and still get the pipe to heat up. More power from the combustion itself, less heating of the cylinder and the pipe temp effect available by rpm switched solenoid directly into the pipe.

Thoughts?

[FastFred]

i think many people , including myself, have raised the floor to some extent. but ive never seen anyone raise it to the transfer tops.

Hi peewee what do you think about TZ350's posts on Team ESE's experiments with razing the exhaust port floor to TPO. I had a look at them, interesting.


a modified Suzuki RG50 engine with the exhaust port floor at TPO.

[wobbly]

Here are the STA numbers for a RSA/W 125 cylinder.
Note that these are the actual port numbers,and do not reflect that the Ex has a huge radius on the timing edge.
Thus in reality the actual Cd of the Ex would reflect that of the transfers,making both capable of the same power. Jan stated that any change in timing of the transfers ( up or down )
would loose power - showing that any increase in Blowdown by reducing the transfers /or visa versa upset the delicate flow balance.
Note also Jan stated that lifting the Ex port floor and reducing the duct volume only worked once the Blowdown had been optimized for best power.

[dutchpower]

Why lifting the exh. port floor on 50 cc give less power Wobbly

[wobbly]

Having an engine with 27% more transfer STA than the Blowdown is so weird I doubt that it would make any power at all, no matter what was done with the Exhaust duct .

[Grumph]

Having an engine with 27% more transfer STA than the Blowdown is so weird I doubt that it would make any power at all, no matter what was done with the Exhaust duct .

What about the case where there's a ring of exhausts above the transfers ? Does sheer port area compensate for blowdown time ?

[wobbly]

The STA concept was developed long ago and has been refined into a user friendly tool that accurately predicts
the power capability of ports that we would regard now as possessing a "normal" 2T scavenging process.
I, and the current scavenging models as are used in code like EngMod, have no way of even beginning to predict what would happen with
weird arse configurations that dont represent the SOTA as we know it.
Though Neels has recently worked on introducing code that accurately models Mr Rygers ( Lucs ) so far very wet dream.

[peewee]

Hi peewee what do you think about TZ350's posts on Team ESE's experiments with razing the exhaust port floor to TPO. I had a look at them, interesting.

I didn't know he had already raised the floor so high. he is the first that I know to do it. ive never seen the ese experiments. is it another section around here ?

[peewee]

Having an engine with 27% more transfer STA than the Blowdown is so weird I doubt that it would make any power at all, no matter what was done with the Exhaust duct .

usually its just the opposite with the engines ive seen. the transfer sta is far to short with little chance of making any improvements without a welding machine and 10lb of filler rod. mainly from terrible stud spacing is to blame I think. the late model ktm dirtbike engines seem to be pretty good however

[TZ350]

ive never seen the ese experiments. is it another section around here ?

This thread started out of Team ESE's efforts to learn about and develop their bikes.

But it is by far and away the excellent and interesting contributions from lots of other people that have made this thread such a good 2T tuning resource.

I am not sure that the Team ESE exhaust port floor at TPO experiments are all that conclusive, interesting but not conclusive.

To follow any link back to its origins, just click on the little blue arrow thing after the quoted persons name.


Blue = Exhaust dam level with TPO. Red = Dam opening 4 deg after TPO.


Exhaust port dam ... Blue = Standard "A" ports, Red = Widened "A" ports. Useful improvement in bottom end power.

[Grumph]

The STA concept was developed long ago and has been refined into a user friendly tool that accurately predicts
the power capability of ports that we would regard now as possessing a "normal" 2T scavenging process.
I, and the current scavenging models as are used in code like EngMod, have no way of even beginning to predict what would happen with
weird arse configurations that dont represent the SOTA as we know it.

That makes two of us, LOL. It's been discussed here and I thought you may have an opinion.

Probably a better use of time to refine the already known.

[wobbly]

I dont understand at all what you are saying peewee,here we have been given a STA printout of a 50cc engine that i assume has been
measured or modified to the specs that show a huge transfer time area, with a Blowdown number not even remotely matched.
What has this got to do with engines you may or may not have seen with stud issues etc.
All I am saying is that with ports so badly mismatched, any result from moving the Exhaust floor,will be masked really badly by the other issue.

[dutchpower]

with ports so badly mismatched !!!!!!!!

[katinas]

Here are the STA numbers for a RSA/W 125 cylinder.
Note that these are the actual port numbers,and do not reflect that the Ex has a huge radius on the timing edge.
Thus in reality the actual Cd of the Ex would reflect that of the transfers,making both capable of the same power. Jan stated that any change in timing of the transfers ( up or down )
would loose power - showing that any increase in Blowdown by reducing the transfers /or visa versa upset the delicate flow balance.
Note also Jan stated that lifting the Ex port floor and reducing the duct volume only worked once the Blowdown had been optimized for best power.

Thank you very much

And with rised Ex floor, there is little more space for additional cooling under floor and cylinder wall.

[F5 Dave]

So finally swapping my Zeel for an Ignitech. So far so easy.

Running std flywheel stator. 1 pickup 2 lobes.
std dual output coil setup. I've wired both CDI outputs to it.

Seems to like,
Standard setting 2 lobes 1or2 pickup setting.
question: does this fire both CDI?

Also RPM test only seems to go to 2000rpm on tacho despite setting.

Cheers.

[katinas]

This is a favorite hobby horse of Ken Seeber and mine.........


Before leaving MotoGP four stroke world , Mr. Furusawa said, that now he will have more time to develope his Yamaha RZ 250 engine cooling pocess !!! Never ending process.

[husaberg]

Before leaving MotoGP four stroke world , Mr. Furusawa said, that now he will have more time to develope his Yamaha RZ 250 engine cooling pocess !!! Never ending process.
It's a sad buy true story that all TZ's right up to the reverse cylinder ran their water in entirely the wrong direction prior to 1988. The cooler water from the rad actually enterered the head and was pushed down. Thus Ensuring the crankcases recieved the hottest water. exactly the opposite of what should happen.
No doubt the rest of the yamaha road bikes suffered the same fate.

[Muhr]

Here are the STA numbers for a RSA/W 125 cylinder.
Note that these are the actual port numbers,and do not reflect that the Ex has a huge radius on the timing edge.
Thus in reality the actual Cd of the Ex would reflect that of the transfers,making both capable of the same power. Jan stated that any change in timing of the transfers ( up or down )
would loose power - showing that any increase in Blowdown by reducing the transfers /or visa versa upset the delicate flow balance.
Note also Jan stated that lifting the Ex port floor and reducing the duct volume only worked once the Blowdown had been optimized for best power.

Thanks

great stuff! :niceone:



usually its just the opposite with the engines ive seen. the transfer sta is far to short with little chance of making any improvements without a welding machine and 10lb of filler rod. mainly from terrible stud spacing is to blame I think. the late model ktm dirtbike engines seem to be pretty good however

Maybe you usually work with bigger cc?


Why lifting the exh. port floor on 50 cc give less power Wobbly

Is it something you are building?
I will follow this with great interest in such a case.
What I do is more conservative.

[wobbly]

F5, yes with the standard setting of 2 lobes,1 or 2 pickups,the default is 2 ignitions per revolution,so as each lobe passes the single trigger
a spark event occurs in both cdi.
Personally I would dump the double ended coil and go with two RS250,RGCV250 coils.

Dutchpower - the Transfer STA being so huge ( as they are very wide obviously ) in comparison to the Blowdown STA, means that if the Delivery Ratio is sufficient to
actually flow enough air to make 38.9Hp via the transfers,then you will get the classic scenario of a huge residual combustion pressure at TPO.
The nowhere near sufficient Blowdown will create a large reverse flow down the A transfer ducts, as they open first, creating havoc with the scavenging regime.
So I believe that when you have a fatally flawed scavenging setup like that, lifting the Ex duct floor for sure wont be able to increase power.
The perfect example was shown by Jan when developing the Aprilia, that lifting the duct floor only made power once the Blowdown was optimally matched to the Transfer STA.

[F5 Dave]

Thank Wob. Yeah on lookout for RGV coils but run what I've got for now.
Any thoughts on the low test tachometer? Yet to start it to see what it does running. I did a mod on the early R1 dash to suit the Zeel. May reverse it.

[Jannem]

334752



Makes me wonder why Aprilia went with the intake side offset cylinder head for ditech, as it's already proven not to be that great. To get the plug to the hot side?

One of the ideas I've pondered experimenting with, is to offset the chamber to the exhaust side. That approach is proven to work very well in 4-strokes allowing a lot more compression and reduced ignition lead, but can't say what to anticipate in 2-stroke. Should at least improve the piston cooling and charge vaporization somewhat. Easy to try though.