ESE's works engine tuner

[husaberg]

And, if you've got a spare half hour, you might find this interesting:

https://www.facebook.com/classic2strokes/videos/556611441588994/UzpfSTczNzg3NTU1MDoyNzE0NzkwNzY4NjEwMzMz/


includes, EFI, oil strategy, carbon fibre, coolant pump, Britten etc

Enjoy

Shocks like an old Yamaha
344004

[F5 Dave]

I've used 0.3 cf regularly. Used to replace it when the edges got brinneled, sort of wearing through smooth surface to the weave, but that took a race season at least.

[katinas]

Ken, petals damage character looks like from deformation in to the window, from positive high pressure in transfers tunnels, or negative from piston moving up from BDC or impact deformation. With thicker petals I cant see any signs of damage, so temperature maybe not a big cause.
Looks like higher pressure in transfer tunnels resist more to hot gases.

Use piston from previous tests with RGV cylinder with two exhaust windows, so this piston partly masked A and weakened pulse when piston moves up. I simply want to test until the end of this year so have no time to made proper piston to NS cylinder with one exhaust window, that left more room to cut piston and fully open A, same like B when piston moves up. Add picture with red line.

[katinas]

Your leap is a petal i English named after a flower Petals

https://cdn.pixabay.com/photo/2017/02/23/00/06/flower-2091017_960_720.jpg
Your English is great btw.

Two stroke with flowers and cat from beautiful Sardinia

[SwePatrick]

Ken, petals damage character looks like from deformation in to the window, from positive high pressure in transfers tunnels, or negative from piston moving up from BDC or impact deformation. With thicker petals I cant see any signs of damage, so temperature maybe not a big cause.
Looks like higher pressure in transfer tunnels resist more to hot gases.

Use piston from previous tests with RGV cylinder with two exhaust windows, so this piston partly masked A and weakened pulse when piston moves up. I simply want to test until the end of this year so have no time to made proper piston to NS cylinder with one exhaust window, that left more room to cut piston and fully open A, same like B when piston moves up. Add picture with red line.

Katinas,
What alloy do you make your pistons of?

[katinas]

All pistons, from Rygerised to RGV, made from the same 2618 T6 alloy. I like to made them from lower linear thermal expansion 4032, but cant get rod easily. With 2618, more clearance needed.

Honda for GP racers pistons used EN AB 48000 ( add pdf ), for cylinders EN AB 46200 http://www.trimet.cz/en/sv_EN_AB-46200.php
https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19990019483.pdf
http://blog.jepistons.com/2618-vs.-4032-material-differences
http://www.aluminiumbozen.com/en/cms/54/4032.html

Add two photos of the same piston for NS cylinder that changed through two years of testing and ended with fallen spark plug ceramic

[MotleyCrue]

The picture of the F750 exhaust back on page 2199 shows the merge point of the exhaust from adjacent cylinders quite a long ways from the port, to make the 4 into 2 exhaust. I don't know much about that engine, but my question is not about that engine. My question is about where the ideal location is to make the merge on a normal twin cylinder engine. On twin cylinder engines it was my understanding that a 2-1 exhaust should have the merge as close as possible to the engine without making crazy bends. But what would happen if the merge was not until way down the exhaust say near the end of the diverging section, in a case where the rules demand a 2-1 exhaust but are not specific. No merging at the stinger is not an option, that would get tossed out for sure. Would making the merge much farther along the exhaust be better, or worse than making it close to the engine ?

Also if the best location for the merge is deemed to be right after a short length of head pipe, is there a best angle to merge the two head pipes into one and ideally how much bigger should the single pipe be than the individual pipes right at the merge? 50% bigger in area ?

[Muciek]

Maybe those photos will help somewhat with your question. It was designed way back (by Kevin Cameron for Daytona) but it worked. Next option would be spending some time with Engmod...
http://www.natsforum.net/viewtopic.php?f=9&t=174&start=290#p3252

[husaberg]

Maybe those photos will help somewhat with your question. It was designed way back (by Kevin Cameron for Daytona) but it worked. Next option would be spending some time with Engmod...
http://www.natsforum.net/viewtopic.php?f=9&t=174&start=290#p3252

Cameron used second hand rusty sheet steel for his as it was all he had about at the time. Its mention in a TDC in CW or the book or both
Some art lady wanted to exhibit it as artwork.
click three times344048

[MotleyCrue]

Maybe those photos will help somewhat with your question. It was designed way back (by Kevin Cameron for Daytona) but it worked. Next option would be spending some time with Engmod...
http://www.natsforum.net/viewtopic.php?f=9&t=174&start=290#p3252

Thanks for the link. I would guess that it doesn't work on twins and that's why no one uses it, just thought that Wobbly or someone might have tried it or knew of someone that did and knew what the results were. I guess what I'm saying is that I'm not trying to re-invent the wheel (Engmod etc.) the factual knowledge is surely already out there.

[diesel pig]

The picture of the F750 exhaust back on page 2199 shows the merge point of the exhaust from adjacent cylinders quite a long ways from the port, to make the 4 into 2 exhaust. I don't know much about that engine, but my question is not about that engine. My question is about where the ideal location is to make the merge on a normal twin cylinder engine. On twin cylinder engines it was my understanding that a 2-1 exhaust should have the merge as close as possible to the engine without making crazy bends. But what would happen if the merge was not until way down the exhaust say near the end of the diverging section, in a case where the rules demand a 2-1 exhaust but are not specific. No merging at the stinger is not an option, that would get tossed out for sure. Would making the merge much farther along the exhaust be better, or worse than making it close to the engine ?

Also if the best location for the merge is deemed to be right after a short length of head pipe, is there a best angle to merge the two head pipes into one and ideally how much bigger should the single pipe be than the individual pipes right at the merge? 50% bigger in area ?

Your best bet is to look into snowmobile and jet ski tuning web sites as some of them use twin engine single pipe set ups.

[wobbly]

Trouble is we are seeing engines with 2:1 pipes that are pairing different cylinder phasing.
There are the 180* firing pairs , and pairs firing together.
Trying to deuce what " works " is thus a nightmare.
All I know is that I spent months in EngMod trying to logically work thru the possible combinations for a Yamaha fan cooled 180* twin used in a miniature aircraft.
What I leaned was that huge Ex port duration's are mandatory , short Y headers work the best , and finally , that no matter what you will never approach the power of individual chambers.
You can " cheat " the system by having the Ex port bottoms open with the pistons at TDC , but at the time I did this we were using pumper carbs.
Fuel injection would work - carbs I seriously doubt it.
Jet skis use 2:1 for simplicity of packaging and cost.But they can recover alot of the lost power using clever water injection strategies.
Not much help I know , but thats all I got.

[MotleyCrue]

Trouble is we are seeing engines with 2:1 pipes that are pairing different cylinder phasing.
There are the 180* firing pairs , and pairs firing together.
Trying to deuce what " works " is thus a nightmare.
All I know is that I spent months in EngMod trying to logically work thru the possible combinations for a Yamaha fan cooled 180* twin used in a miniature aircraft.
What I leaned was that huge Ex port duration's are mandatory , short Y headers work the best , and finally , that no matter what you will never approach the power of individual chambers.
You can " cheat " the system by having the Ex port bottoms open with the pistons at TDC , but at the time I did this we were using pumper carbs.
Fuel injection would work - carbs I seriously doubt it.
Jet skis use 2:1 for simplicity of packaging and cost.But they can recover alot of the lost power using clever water injection strategies.
Not much help I know , but thats all I got.

180 firing pairs is what I was thinking of. Since the power is not as high as with individual pipes. snowmobile and jet ski engines sites don't seem to really have a lot to offer, not at the level that is normal on this site. Assuming a short Y header is there any sort of rule of thumb as to how big the single pipe exiting the merge should be?

In a way it would seem like at the merge the cross sectional area of the single pipe should be equal to the cross sectional area of pipe 1 and pipe 2 summed up, but then with a different train of thought it seems like maybe the cross sectional area of the single exit pipe should be the same as just one individual pipe at the merge. I think in practice people have the cross sectional area of the single pipe as somewhere between 1 and 2 times the cross sectional area of one individual pipe, but there must be an optimal value or range I would guess?

[Haufen]

Happy New Year to everyone!

Anyone else going to attend the two-stroke engine conference in Paris mid February?

2-stroke engine conference (http://di2-stroke-engine.ifp-school.com)

Edit: you can also download the 2018 presentations here (https://drive.google.com/drive/folders/1lIR2GrILqeNl6lF0Pp_Gsp7R1OTJQRdm)

[husaberg]

Geoffrey Cathcart
Chief Technology Officer at Orbital Australia Pty Ltd
Perth, Australia

[jbiplane]

We saw exist V engines where angle beetween cylinders differs from 90, says 112 with 24degree pins offset.
Just curious may be says 168 degree boxer will be a bit less violent engine than 180?
Then it will be a bit shifted ignition in both cylinders less crankshafl loads and probably smoother torque?

[wobbly]

That idea may , just may have some technical merit , but trying to package a 168 V 2T into a real bike would way offset any advantage gained by the configuration itself.

[Vannik]

Does anyone have the crankcase volume or primary compression ratio for a Maico 440? And is it inclusive or exclusive of the transfer port passage volumes?

[flyincat]

The picture of the F750 exhaust back on page 2199 shows the merge point of the exhaust from adjacent cylinders quite a long ways from the port, to make the 4 into 2 exhaust. I don't know much about that engine, but my question is not about that engine. My question is about where the ideal location is to make the merge on a normal twin cylinder engine. On twin cylinder engines it was my understanding that a 2-1 exhaust should have the merge as close as possible to the engine without making crazy bends. But what would happen if the merge was not until way down the exhaust say near the end of the diverging section, in a case where the rules demand a 2-1 exhaust but are not specific. No merging at the stinger is not an option, that would get tossed out for sure. Would making the merge much farther along the exhaust be better, or worse than making it close to the engine ?

Also if the best location for the merge is deemed to be right after a short length of head pipe, is there a best angle to merge the two head pipes into one and ideally how much bigger should the single pipe be than the individual pipes right at the merge? 50% bigger in area ?

I'd look at snowmobiles for latest and greatest design for twins. Just about everything for the last 15+ years has been parallel twins (180* firing) with 2:1 single pipe.

The example, below, is the way NOT to design a y-pipe. This stock OEM design was one of the worst in modern two stroke snowmobiles. Speculation chalked the poor design up to noise/emissions regulations dictating the less than stellar design. It's interesting to note the indented area on the top and bottom, likely trying to maintain cross sectional area at the merge. Quite a few OEM y pipe designs have similar indents.

344076344075344074

Below is an aftermarket replacement for the above poor stock design. This design is known to gain a quick 6% HP! Interesting to note is the generous bend going into the outlet....much larger radius than the stock design. Also, the indent is removed, top and bottom. I'm not sure if the indent removal has much effect or was left out for fabrication reasons.

344073

Finally is another aftermarket design, below. This has similar gains to the other aftermarket unit. The biggest difference here is the much longer runners and even straighter angle into the outlet.

344077

I would guess the Stock design loses major pipe energy at the merge into the single outlet with the steep angle, much greater than 90* between the legs at the merge.

[dutchpower]

Does anyone have the crankcase volume or primary compression ratio for a Maico 440? And is it inclusive or exclusive of the transfer port passage volumes?

820 cc incl.transfer

[Vannik]

820 cc incl.transfer

Thank you!

[JanBros]

aparently there was an error in a BMEP-link in my 2-stroke excel, fixed it now.

and now there is a way of printing the portmap to actual size, so you can print it, cut out the ports and place it in your cylinder to see where you have to grind the ports some more.

links in updated topic : https://www.kiwibiker.co.nz/forums/showthread.php/187285-2-stroke-excel-for-ports-heads-and-pipes

anyone used it already ? any comments ?

[jfn2]

JanBros
I seem to have a problem bring up your second (revised) edition in my excel program. Your first edition worked fine. I admit I have a dated excel program. By the way, it looks like a very nice program.

[wobbly]

A customer wants a new pipe design , the existing pipe is rumored to be a Aprilia Type 21 , I had this design on an old hard drive I cant find.
Anyone got the dimensions ?

[teriks]

Vagelis posted that and a few more on PitLane some time ago.
http://www.pit-lane.biz/t3173p975-gp125-all-that-you-wanted-to-know-on-aprilia-rsa-125-and-more-by-mr-jan-thiel-and-mr-frits-overmars-part-2-locked

Tubo21 from his post
344141

[husaberg]

Vagelis posted that and a few more on PitLane some time ago.
http://www.pit-lane.biz/t3173p975-gp125-all-that-you-wanted-to-know-on-aprilia-rsa-125-and-more-by-mr-jan-thiel-and-mr-frits-overmars-part-2-locked

Tubo21 from his post
344141
Here is afew more compared
https://www.kiwibiker.co.nz/forums/album.php?albumid=4854&attachmentid=310144
https://www.kiwibiker.co.nz/forums/album.php?albumid=4854&page=3
I cant remember what this one was though?
One of Wobs?
https://www.kiwibiker.co.nz/forums/album.php?albumid=4854&attachmentid=310087

[andreas]

Aha why not three times

[JanBros]

JanBros
I seem to have a problem bring up your second (revised) edition in my excel program. Your first edition worked fine. I admit I have a dated excel program. By the way, it looks like a very nice program.

If you want me to help, you'll have to explain the problem :msn-wink:

[Frits Overmars]

A customer wants a new pipe design , the existing pipe is rumored to be a Aprilia Type 21 , I had this design on an old hard drive I cant find. Anyone got the dimensions ?Take your pic, Wob.
344143

[jfn2]

JanBros
Sent you a PM (I think).

[teriks]

Take your pic, Wob.
344143
^^ ..and there I guess we have the source of Vagelis version.

[Emily Strange]

Good morning. My name is Emily, this is my first comment on this forum although I've been a lurker for a year or so.

I have been heavily involved in two stroke bikes for over forty years now including racing, and crashing, most of the classic two stroke bikes that are now worth a small fortune. My interest is mainly engine development and technology, this thread has been highly educational as well as amusing at times. I am involved in development of two stroke engines, usually at my own expense(!) but increasingly companies are looking outside of the usual four stoke/ diesel engines for alternative technology, there is a huge amount of attention to patents many going back decades.

Changing subject but still involved with the two strokes there are many new aerospace plating technologies coming through and on the horizon. Although there are or will be technical challenges to overcome some of the new low friction plating technologies are opening up the possibility of ultra low oil through the two stroke engine, with the ultimate possibility of no oil becoming a reality in the near future. This is just one of the fields that I am working in.

Can I add my thanks to Frits Overmars and Jan Thiel for your input and sharing of knowledge? We all stand on the shoulders of giants relying on previous peoples efforts before pushing the boundaries to add our own little advances but the progress that these two Gentlemen have added to the world of two stroke engines cannot be underestimated. To me they have brought in the third age of two stroke engineering, the first being Walter Kaaden & MZ in the Eastern Block and the second being the Degner and Suzuki, et al developments.

Frits do you still work or consult in the field of two strokes? Perhaps a message or some way of a quick private exchange can be arranged? I would be very grateful if this can be achieved. And can I add my vote that a book would be very well received? No pressure... ;-)
I write technical books from time to time and translate some Japanese manuals to English occasionally.

That's enough for now! I'm happy to see that reports of the death of the two stroke are premature to say the least! Keep up the good work guys.

[Frits Overmars]

That was quite an intriguing presentation Emily, you certainly know how to make someone curious.
I still do some consultancy work, mainly in the field of two-stroke engines, with chassis design as a second hobby, so my days are well filled. Nevertheless, I agree that we should be in contact with each other, but as a form of self-protection, I have blocked private messages in the public forums that I visit, and I try to keep my mail and phone details to myself. If I do wish to communicate privately, I prefer to do so via email, and not via telephone, Whatsapp or, God forbid, Fakebook.
If you wish, you can leave your e-mail address at the temporary address xxxx@yyyyy.zzz (fos@hetnet.nl). Anyone who uses this address uninvited will be punished with a fate worse than death. I don't know exactly how yet, but I will think of something extremely frightening.

Well, we finished that. Can you tell us some more about yourself and about your activities Emily? With images maybe?

[Emily Strange]

Hi Frits,

Thank you for your prompt reply. I have sent a message to your email address please modify your post to delete the email address.

I am happy to share information and discuss things with you and everybody on here. I am however subject to a number on non-disclosure agreements so I will not be able to discuss anything other than publicly available information on some subjects.

I will dig some photo's out and post them when I have a spare minute or two.

Emily.

[MotleyCrue]

If there were a way to run a square top edge on the exhaust port, and similarly remove the bridge between A and B ports, or the bridge between B and C ports, while still running a square top edge on those ports, all without breaking rings, would you, and if so which of the 3 changes would you make ?

[wobbly]

There is already the technology to run a square top edge at 100% bore with no bridge.
This involves an inverted L dykes ring that is trapped within a groove.
The piston " lid " screws on to contain the ring from bulging out into any port.
This can also be combined with removing the small end pin hole from the outer skirt - and is being worked on now by Makr and Mr Two Stroke Stuffing ( I have the T shirt )
But deleting the transfer bridges will , I believe , completely ruin the exiting streams coherency , that has been worked on for decades to create Frits Leaning Tower up the back wall.
Thus destroying the scavenging and trapping efficiency in one foul swoop.
Transfer STA has rarely been the limiting issue , Blowdown certainly has been.

[Emily Strange]

'Frits Leaning Tower up the back wall'

I'm sure he will thank you for that! Gave me a good laugh. Yamaha had the YPVS (known to some in the UK as the Young Persons Vigorous Sausage!), Kawasaki had KIPS (you'll have to make your own interpretation up for that one) and Aprilia have the FLTUTBW... Yikes.!

[MotleyCrue]

There is already the technology to run a square top edge at 100% bore with no bridge.
This involves an inverted L dykes ring that is trapped within a groove.
The piston " lid " screws on to contain the ring from bulging out into any port.
This can also be combined with removing the small end pin hole from the outer skirt - and is being worked on now by Makr and Mr Two Stroke Stuffing ( I have the T shirt )
But deleting the transfer bridges will , I believe , completely ruin the exiting streams coherency , that has been worked on for decades to create Frits Leaning Tower up the back wall.
Thus destroying the scavenging and trapping efficiency in one foul swoop.
Transfer STA has rarely been the limiting issue , Blowdown certainly has been.

Is this developed enough that it is known to stay together (screws don't come loose, top doesn't overheat, screws don't overheat) and would work on any engine (retrofit) or is it in the guinea pig stage?

[JanBros]

<img src="https://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=344143&amp;stc=1" attachmentid="344143" alt="" id="vbattach_344143" class="previewthumb">
any theory/explanation behind the slghtly conical belly ?
benefits/downsides ?

[wobbly]

There is a finite amount of energy available from the Ex port generated wave front within the pipe.
In Aprilias case the diffuser action must have been more efficient than the trapping efficiency numbers.
Thus the angles needed in the rear cone gave better power the steeper they were.
Tapering the mid section allows a bias to be generated toward scavenging ( bigger front mid section ) or toward trapping ( bigger mid section end ).
I have done several designs where scavenging needed additional help , so the diffuser needed to be steeper.
The new TM KZ engine is an example - in this case I needed to make the last diffuser way steep to generate better front side power , and the rear cone could not be as steep as it limited overev ability
thus the mid taper is reversed.

[wobbly]

The screw together piston dome has a patent issued for it , and has been tested to death .
Makr is using his idea of a two piece piston to allow a full length outer skirt with no pin holes and is combining the two together for an even better design.
Not sure about how he is ensuring reliability - search his SpewTube posts.

[andreas]

There is a finite amount of energy available from the Ex port generated wave front within the pipe.
In Aprilias case the diffuser action must have been more efficient than the trapping efficiency numbers.
Thus the angles needed in the rear cone gave better power the steeper they were.
Tapering the mid section allows a bias to be generated toward scavenging ( bigger front mid section ) or toward trapping ( bigger mid section end ).
I have done several designs where scavenging needed additional help , so the diffuser needed to be steeper.
The new TM KZ engine is an example - in this case I needed to make the last diffuser way steep to generate better front side power , and the rear cone could not be as steep as it limited overev ability
thus the mid taper is reversed.

Wobbly are you sure this is correct, the best way to acheive balance between negative and positive wave must be mid- sec diameter, having the belly tapering out just for the baffle to have steeper cones wouldn't increase ramming efficiency, that is as in higher amplitude-they are still the same length? in fact some energy has been lost. I'm not aquainted with the Helmholtz factor of things, maybe this is the reason.

[andreas]

duplicate.

[wobbly]

The convergent cones wave amplitude is directly proportional to the reflecting angle - steeper = higher amplitude.
Wave duration is directly proportional to cone length - longer cones = longer duration.
In the case of a larger belly diameter for the reflecting cone we get the best of both worlds , identical duration ( same length ) with higher amplitude ( steeper cone angle ).
Normally to get steeper angles you would need to shorten the cone length , thereby automatically reducing the duration , and to some extent this relates to powerband width as well.
Having a parallel mid section means that you have no bias in the use of the finite wave energy available - going bigger means the diffuser is affected ,thus reducing the available energy for the reflection intensity.
Sure the reflecting cones then by definition become steeper - but that may not be what the engines dynamic system needs, and as less energy is available the steeper rear cones will not in fact have any greater amplitude.
Swings and roundabouts - and zero free lunch as always.

[jfn2]

wobbly:
when dynoing an engine and monitoring pipe info how important is monitoring pipe average pressure (in the center of the pipe) and what +/- psi would that be? I am assuming that the psi is taken when the avg temp is +/- 425*F. I am told that this pressure is +/- 4 psi. Is that true or just bs?

[andreas]

Wobbly I humbly dissagree, free lunch is available at the diffuser, where bigger pipes offer steeper angles with the same length, but the remaining wave that enters the baffle contains less energy than it would have in a smaller pipe, it is also more expanded with means a steeper angle is needed to give it the same reflection profile, but it has still lost some of its energy to the more efficient diffuser. This is theory, I have no proof.

[peewee]

hey guys i have some wossner pistons of 64mm and 225gram with no pin. i guess the machinist is lazy and doesnt give a shit. the same wiseco is just 185g. what do you think the extra strain on the conrod will be at 4000fpm piston speed?

[wobbly]

Your circular argument to me is self defeating in that you say bigger ( parallel ) pipes offer steeper angles with the same length - correct.
But then you say the bigger dia reflecting cone needs steeper angles to generate the same amplitude profile - correct.
And you then agree that the bigger diffuser has " stolen " some of the energy from the reflecting cone so this will by default reduce the rear cones efficiency.
So , the only way to fix that issue - if that is what is needed to make more power - is to increase the rear cones efficiency again by making its entry diameter bigger.
Thus we are back to biasing the efficiency as needed by using a tapering mid section.
Oh - and by the way EngMod agrees , that fact may be moot to some , but also the dyno doesn't lie , and that we can all agree on implicitly.

[andreas]

Having the baffle cone's entry diameter larger than the diffuser cone's outlet makes the belly itself a shallow diffuser- stealing more energy, and yet this baffle cone returns more energy- where does the extra energy come from?

[F5 Dave]

I shouldn't be drinking while reading this (Epic Hop Zombie double IPA 8.5%) as this is melting my brain. I'm going to have to draw some pictures. Must go spend some time with Mal down the road and get my head around pipe dynamics in Engmod.

[jato]

hey guys i have some wossner pistons of 64mm and 225gram with no pin. i guess the machinist is lazy and doesnt give a shit. the same wiseco is just 185g. what do you think the extra strain on the conrod will be at 4000fpm piston speed?

I get around 1800 newtons extra load using stroke/rod length/revs of a tz 350 ,so thats most of 180 kg extra. I'd be a bit nervous at real high rpm...

[peewee]

I get around 1800 newtons extra load using stroke/rod length/revs of a tz 350 ,so thats most of 180 kg extra. I'd be a bit nervous at real high rpm...

yes im a bit nervous. i dont know why it would be that heavy. even 250cc piston with stronger conrods are less than 225g. maybe i call wossner tomorow

[jamathi]

[QUOTE=wobbly;1131150899]There is a finite amount of energy available from the Ex port generated wave front within the pipe.
In Aprilias case the diffuser action must have been more efficient than the trapping efficiency numbers.
Thus the angles needed in the rear cone gave better power the steeper they were.
Tapering the mid section allows a bias to be generated toward scavenging ( bigger front mid section ) or toward trapping ( bigger mid section end ).
I have done several designs where scavenging needed additional help , so the diffuser needed to be steeper.
The new TM KZ engine is an example - in this case I needed to make the last diffuser way steep to generate better front side power , and the rear cone could not be as steep as it limited overev ability
thus the mid taper is reversed.[

Longer and steeper rear cones were already used on the 50 & 125 Bultaco's in 1979 when I worked there. So of course the max diameter had to be bigger!
It also worked very well on the Minarelli & Garelli 125cc twins.
And in 1995 on the Aprilia!

Your TM exhaust looks really WONDERFUL!

[jbiplane]

All pistons, from Rygerised to RGV

According my experience Rugerised engine very heavy to start. Seems I have to increase piston squirt from intake side or do something else.
Sometimes we gives up in attempts to start 550cc engine witg pull starter. If launched works well, but really hard to start.

[jonny quest]

https://www.motorsportmagazine.com/news/f1/two-stroke-engines-eco-fuel-f1-aims-be-greener-formula-e

[wobbly]

Andreas , the very very shallow angle of the mid section , be it expanding or contracting , has only a tiny effect in comparison to what can be achieved with the much steeper cones on one side of it.
It does affect belly volume as well , but again only marginally % wise.
In the TM design I did the bias was needed in favor of the last diffuser , as this made instant front side power, in the sim and on the dyno.
But at the same time the 3 section rear cone was overly efficient in that with the same entry diameter as the enlarged diffuser end , it shut off too hard over the top of the powerband.
I tried longer and shallower rear cone angles , and this gained some overev , but at the expense of too much peak power ( I think this came down to the reflection duration now being too long ).
The next step was to reduce the convergent entry diameter.
This helped the overev shutoff rate ( alot ), and to my delight - lost only a tiny amount of peak.

[wobbly]

Jan , as Frits would say " thank you for the flowers ".
But the TM job would not have happened without your support - to this day I cant tell if Franco is grateful or annoyed ( maybe both equally ) that the new
design was even better than he asked for.

[Pursang]

https://www.motorsportmagazine.com/news/f1/two-stroke-engines-eco-fuel-f1-aims-be-greener-formula-e

All Very encouraging.......Until: "the design would be more prescriptive in an effort to keep a lid on costs".:crazy:

They want to encourage development of exciting, new, powerful and environmentally effective engines, then restrict how this will be done.:brick:

Typical of F1!!

How about just specifying a maximum engine capacity and maximum emission levels (operating output PLUS construction & environmental disposal).
Then let the greatest innovators and engineers produce their solutions.
Variety of options is what the highest levels of motorsport require, Not uniformity! I reckon 'real' F1 died in the 70's.:zzzz:

cheers, Daryl.

[andreas]

Andreas , the very very shallow angle of the mid section , be it expanding or contracting , has only a tiny effect in comparison to what can be achieved with the much steeper cones on one side of it.
It does affect belly volume as well , but again only marginally % wise.
In the TM design I did the bias was needed in favor of the last diffuser , as this made instant front side power, in the sim and on the dyno.
But at the same time the 3 section rear cone was overly efficient in that with the same entry diameter as the enlarged diffuser end , it shut off too hard over the top of the powerband.
I tried longer and shallower rear cone angles , and this gained some overev , but at the expense of too much peak power ( I think this came down to the reflection duration now being too long ).
The next step was to reduce the convergent entry diameter.
This helped the overev shutoff rate ( alot ), and to my delight - lost only a tiny amount of peak.

Yes ok, I follow your work with great interrest.

[jamathi]

Jan , as Frits would say " thank you for the flowers ".
But the TM job would not have happened without your support - to this day I cant tell if Franco is grateful or annoyed ( maybe both equally ) that the new
design was even better than he asked for.

Franco will be operated next week, he has a tumor in his throat.....

[TZ350]

I reckon 'real' F1 died in the 70's.:zzzz:

cheers, Daryl.

I absolutely agree ..........

[TZ350]

According my experience Rugerised engine very heavy to start. Sometimes we gives up in attempts to start 550cc engine witg pull starter. If launched works well, but really hard to start.

344181 this is what I use with difficult engines.

[Frits Overmars]

They want to encourage development of exciting, new, powerful and environmentally effective engines, then restrict how this will be done. Typical of F1! How about just specifying a maximum engine capacity and maximum emission levels (operating output PLUS construction & environmental disposal).An important aspect when drawing up rules is: you must be able to measure what you prescribe.
Measuring those emission levels would be a hell of a job; you'd have to chase those F1 cars. Or you could measure them at a fixed set of circumstances on a dyno. Just ask VW how it's done.
Joking apart, if you specify maximum emission levels, you no longer need to limit the engine capacity as well. This approach is not entirely new; decades ago Keith Duckworth of Cosworth fame proposed to limit only the fuel consumption in F1. The environment was not yet invented back then, but it would at least have limited CO2 emissions. And engine-wise it would have been a free-for-all: two-strokes, fourstrokes, diesels, turbines, fuel cells, you name it. That would really bring out the best form of propulsion (Duckworth secretly thought of a two-stroke providing the exhaust gases for a turbine that powered the gearbox).

[ken seeber]

Frits, good timing, was thinking about the same thing:

Jeez, if it was true then great. Suggest we forget all that CC stuff:

1. Fixed volume of fuel issued to all competitors prior to start
2. Must use at least 5 gears per lap (ie from 1st to 5th)
3. Regen via hybrid is ok
4. Batteries must be capacitive only and demonstratably empty prior to start of race.
5. Minimum noise level of XXX dBa past the start/finish line every pass.
6. Probably have to chuck in all the current safety stuff
7. Only one car per even per driver
8. One tyre for the total event (wet, dry or both), single supplier
9. Anything else ???

[Pursang]

An important aspect when drawing up rules is: you must be able to measure what you prescribe.
Measuring those emission levels would be a hell of a job; you'd have to chase those F1 cars. Or you could measure them at a fixed set of circumstances on a dyno. Just ask VW how it's done.
Joking apart, if you specify maximum emission levels, you no longer need to limit the engine capacity as well. This approach is not entirely new; decades ago Keith Duckworth of Cosworth fame proposed to limit only the fuel consumption in F1. The environment was not yet invented back then, but it would at least have limited CO2 emissions. And engine-wise it would have been a free-for-all: two-strokes, fourstrokes, diesels, turbines, fuel cells, you name it. That would really bring out the best form of propulsion (Duckworth secretly thought of a two-stroke providing the exhaust gases for a turbine that powered the gearbox).

Agreed, with such a varied range of propulsion solutions, individual monitoring is not a good option.

Let each Entrant determine their own emission levels.:innocent:
All Measurements, assumptions and calculations to be publicly available for review by their peers, and any other interested parties.

(Propulsion Engineering) Protests to be adjudicated by an independent panel of Scientists and Engineers. Not race promoters..:hitcher:
All protests must be supported by appropriate Measurements, assumptions and calculations, not a "they're too quick, I think they must be cheating":girlfight:
On-board management system transmissions are recorded by the race committee during events, for review by the Protest Panel, if required.
Protest process & results including all Measurements, assumptions and calculations to be publicly available for review by their peers, and any other interested parties.

Very Public Humiliation for Cheats! :spanking: (ask VW what that feels like & costs)
Clever interpretations of the Rules, on the other hand, will be available for further consideration, by all entrants and interested parties.

Assumes that F1 wants to be seen as being at the leading edge of technological development, not just mobile billboards, all moving at the same speed.:rolleyes:

Cheers, Daryl

[Frits Overmars]

Clever interpretations of the RulesDaryl, I have evenly divided a good deal of my time between writing regulations and finding loopholes. If the rules are open to interpretation, they suck.


Assumes that F1 wants to be seen as being at the leading edge of technological development.Sure, F1 wants to be seen as that, which is not at all saying that they really want to be it.
When I think of all the developments they blocked (two-stroke engines, continuously variable transmission and active suspension are just a few)...
If someone asks you whether an idea will work, just point at their rulebook: if it's banned, it would have worked.

[katinas]

According my experience Rugerised engine very heavy to start. Seems I have to increase piston squirt from intake side or do something else.
Sometimes we gives up in attempts to start 550cc engine witg pull starter. If launched works well, but really hard to start.

Interesting to hear about your work results with very nice parts.

If your CreizKopf engine cylinder intake/transfer route is like on the std RMZ 550 engine, without any direct tunnels to transfer ports and all mass from reeds flow directly to under piston space through one intake center window, then piston skirt bottom line from A-B-C-B-A must be much lower. As low as transfer windows stay still closed when piston is at TDC. And from that point, step by step, try to cut skirt. I think this help extract even more torque through all rev range. But anyway, it would be more or less usual scavenge engine.

Good thing, is that unloaded main piston allow to work piston skirt bottom line in suction mode all the way through A-B-C-B-A and this opens many variations.
With your engine, it would be very interesting if you close the std cylinder reed cage space, just only left C long tunnel, and made all reed intake stuff on the new under cylinder spacer ( red line). Then it is possible to arrange all flow directly to A B transfer tunnels, around suds on this engine, with blocked cylinder side cutouts.
With C, two different variation would be interesting to try
One, C tunnel isolated from reed space and help release pressure under piston at BDC
Other, C tunnel works in the same way as A and B, but to release pressure under piston at BDC, additional reeds needed.

[katinas]

https://www.motorsportmagazine.com/news/f1/two-stroke-engines-eco-fuel-f1-aims-be-greener-formula-e
Its hard to believed, especially after future perspective of Moto GP 250kg Energica monsters, but as it still not the first day of April, its very nice news.

Time to get up.

[Flettner]

Ok, technically we have
Dry top end

Uniflow scavenge, without the traditional uniflow transfer issues

HCCI via sudden compression increase to initiate combustion

This all smells of efficiency and low emission all combined into one unit, what is stopping us?

[Pursang]

Sure, F1 wants to be seen as that, which is not at all saying that they really want to be it.
When I think of all the developments they blocked (active suspension and continuously variable transmission are just a few)...
If someone asks you whether an idea will work, just point at their rulebook: if it's banned, it would have worked.

"if it's banned, it would have worked"..... :laugh: & :weep:

[F5 Dave]

But it won't start me watching car racing . Still be a snore.

[JanBros]

about my excel : another small error has come up : on the Data page , in cell Q14 both "exhaust new" should be "exhaust old" , so change it yourself or download it again. it's corrected now.

it resulted in not showing the A.A, T.A and STA for "exhaust old" in a specific circumstance.

[jbiplane]

Interesting to hear about your work results with very nice parts.
If your CreizKopf engine cylinder intake/transfer route is like on the std RMZ 550 engine...

Hello Katinas. Thanks for valuable and interesting comments. Seems this project will a bit stagnated cause it was made as experiment without real customer and few next months I will have some urgent orders to perform. Yes, seems skirt from intake side should be lower. Besides RMZ carburetors inclined outward and fuel goes out of carburetor on ground. In cold warehouse where I tried to start engine last time it was about -6C which make start even more complicate. And pull starter... It was better have less than 550cc engine as test bench.

At moment to start work only pervert way put some fuel in cylinder directly and when sometimes it start, sometimes not. Probably I should make new “long skirt” pistons, install electrical starter and may be fuel injection. May be it will happen few months later. Will share when will have good news.

[wobbly]

JFN2 - in all the excitement of the pipe dynamics discussion I forgot about your pressure question.
The only time I have measured pressure was in a race Jetski to try and find the optimum point to turn on the water injection in the stinger to boost top end power.
Simply using a 0-5psi gauge on a 1M long piece of pipe.
That measured 3psi ( average obviously ) under full acceleration.
The pressure generated though , seems to me not particularly enlightening.
It is created by the bleed rate from the stinger , and that can be optimized in EngMod by looking at the Mach at the nozzle if it has one , or within the straight stinger pipe if not.
This operates best when peaking at 0.8 Mach.

[jfn2]

wobbly:
Thank you for the reply.The reason I asked this question was this is the explanation given for the read out on a Superflow 902 readout sheet.
ExhPrs psig- this is the average gauge pressure inside the tuned pipe(s) measured with a combination pressure transducer/ open element temperature probe in the fat part of a pipe center section. To generalize, 4.0 psi seems to be optimal in creating max HP in two stroke engines. If backpressure is lower, then power might be sacrificed. But then there is less possibility of detonation-producing active radicals being packed back into the combustion chamber by the pipe(s) return sound wave(s).

Then again I don't know what "active radicals" are either.

[wobbly]

Yea sure 4psig may be a rule of thumb for average pipe residual pressure , but I bet that is closely tied to the bmep generated , so not a good point to be heading for , depending if its an MX or GP bike spec..
Also the lower the residual pressure the lower the pipe efficiency , thus big stingers generate better bottom end ( at the expense of topend ) so horses for courses applies.
The only time free radicals are formed in the combustion chamber , is due to excessive pressure and temp creating destructive wave fronts of detonation in the trapped squish end gases.
This can be caused in part by overheated scavenging mixture sitting in the Ex duct , being returned by the plugging wave back into the cylinder.
No radicals are returned from the duct ( simply not enough temp or pressure involved ) - just badly overheated combustion products , that then create the conditions for detonation during the combustion event.
It was suggested by a certain giant engineering tosser that a hot Exhaust duct transferred more energy into the pipe , I proved that wrong by coating a duct with ceramic , the result was a loss of 2Hp and big deto numbers.
This delighted Jan , as it was his ex boss at Aprilia ( The Great Leader ) who proposed this absurd hypothesis and proved it by subsequently building the worst GP engine seen in the modern era.

[Vannik]

And this Great Leader is now going to put Fantic straight:

https://www.motocrossplanet.nl/nieuws-nat/74740/Jan-Witteveen-terug-in-de-motorcross

[ken seeber]

Quote from someone in 2004:



"apriliaforum Junkie Crono's Avatar
--------------------------------------------------------------------------------
Join Date:Aug 2003Location:Catalunya (Spain)Posts:361


Well Witteveen might be the chief engineer, hise xperience howevr came from MX. The real 2 stroke guru behind the succes in 125 , 250 and the 500 2 stroke is work of another Dutchman, Jan Thiel and he is still there. Jan Thiel started in 50 cc in the beginning of the 70's with Jamathi (in fact Jamathi stand for JA (Jan) MA (Martijn) THI (Thiel) Martij Lodewijks was the rider and has been 50cc Worls champion on the bike made by Jan Thiel.
Then he went to Italy, worked at Minarelli, Piovaticci and finally Garelli were he worked with Angel Nieto for years, being worldcgampios in 125 for almost a decade. Angel Nieto also took him to Bultaco and they became again world champion in 50cc.
After the closing of Garelli and Bulktaco he joined Aprilia. He is the guy who design the cilinders and 2 stroke engines and makes them fast.
So 125 and 250 are secured for future. Wiiteveen was lately responsible for MotoGP and the Cube project. Not a succes story. Also Witteveen sacked Dall Igna last year. He joined Gilera!! .. the rest is logcal I think. His project might have mistaken basis. As the 500 V twin, it was in theory a better concept but never won a GP. The Cube 3 cilinder was meant to be a superlight engine. In the real world it never reached it's minimum weight and never worked properly because they strted with a F-1 based Cosworth engine. All together enough to put Witteveen in a not very strong position. "

[Frits Overmars]

Quote from someone in 2004:
"apriliaforum Junkie Crono's Avatar
Well Witteveen might be the chief engineer, hise xperience howevr came from MX. The real 2 stroke guru behind the succes in 125 , 250 and the 500 2 stroke is work of another Dutchman, Jan Thiel and he is still there. Jan Thiel started in 50 cc in the beginning of the 70's with Jamathi (in fact Jamathi stand for JA (Jan) MA (Martijn) THI (Thiel) Martij Lodewijks was the rider and has been 50cc Worls champion on the bike made by Jan Thiel.
Then he went to Italy, worked at Minarelli, Piovaticci and finally Garelli were he worked with Angel Nieto for years, being worldcgampios in 125 for almost a decade. Angel Nieto also took him to Bultaco and they became again world champion in 50cc.
After the closing of Garelli and Bulktaco he joined Aprilia. He is the guy who design the cilinders and 2 stroke engines and makes them fast.
So 125 and 250 are secured for future. Wiiteveen was lately responsible for MotoGP and the Cube project. Not a succes story. Also Witteveen sacked Dall Igna last year. He joined Gilera!! .. the rest is logcal I think. His project might have mistaken basis. As the 500 V twin, it was in theory a better concept but never won a GP. The Cube 3 cilinder was meant to be a superlight engine. In the real world it never reached it's minimum weight and never worked properly because they strted with a F-1 based Cosworth engine. All together enough to put Witteveen in a not very strong position. "A sympathetic story that could do with a correction or two.
Jamathi is derived from JAn THIel and MArtin Mijwaart, who started building racers together in the Netherlands in 1964.
Their companion Paul Lodewijkx, although a top class rider, has never been a world champion. He might have been, but for Angel Nieto running him off the track in Ulster I think it was.
From the Netherlands, Jan and Martin moved to Piovaticci in Italy. A year later they were brought to Bultaco by Angel Nieto.
After Bultaco stopped racing, Jan, Martin and Angel went to Minarelli and when old man Minarelli passed away, Jan and Angel went to Garelli while Martin and his family returned to the Netherlands.
From 1995 to 2004 Jan worked at Aprilia. He never worked on the 500 twin; that was a Witteveen project and Jan Thiel despised it.
At the end of 2004 Jan went from Aprilia to Derbi and Gigi Dalligna wisely decided to follow him. At Derbi Jan designed and developed the bike that later became known as the RSA. When Aprilia, Derbi and Gilera came together under the management of Piaggio, Jan returned to Aprilia, after which he retired in 2008.

[ken seeber]

Frits, well done....

[wobbly]

I met Witteveen in 2000 at Philip Island for a job interview.He was completely full of himself because McWilliams had stuck his Aprilia on pole in 500GP , with completely insane riding skills.
We got into an argument about the " hot exhaust duct concept " - he was wrong , but that wasn't proven till recently.
He also told me anyone who relied on an engine simulator as a tuning tool , was an idiot ( thats you Neels ).
My reaction was that the only idiot in the room was sitting in front of me -funnily I didn't get the job , sadly as working with Jan was a life long dream.
How the guy has managed to bullshit his way into several positions of importance is beyond me to this day , as his arrogance and obvious delusions of grandeur are transparent.

[Vannik]

He also told me anyone who relied on an engine simulator as a tuning tool , was an idiot ( thats you Neels ).


I have to admit though that in 2000 he was not that far wrong - at that stage I still had to convince a certain Wobbly to stop using Dynomation2T and work with me, something I somehow got right.

[ken seeber]

Wob, clearly the cooling of exhaust port & possibly the first stage of the header is the go. You & Jan have demonstrated that.

Looking at the converse, would there be any benefit in insulating the bulk of the divergent cone and the rest of the pipe to retain some thermal energy?

Sounds like he wasn't "witty even" with his bullshit cos he was a wanker.

[husaberg]

Wob, clearly the cooling of exhaust port & possibly the first stage of the header is the go. You & Jan have demonstrated that.

Looking at the converse, would there be any benefit in insulating the bulk of the divergent cone and the rest of the pipe to retain some thermal energy?

Sounds like he wasn't "witty even" with his bullshit cos he was a wanker.

I am no fan but the 400 did have shielding on the pipe.
344232
I believe though its to stop a 250+KM/h air blast cooling the pipe.
Here is a few examples on the 90's and early 2000's sheilds
It also prevents unwanted heat going to the rider or the fairing or the clutch though.
Note Bayles. (click three times)
344230344231

344233344234344235

[wobbly]

Effective cooling of the Ex duct is certainly effective , with the proviso that using the coldest water entering under the duct is NOT the way to go.
Wrapping the header is proven to promote deto due to the returned mixture in front of the piston being overheated , ruining the trapped charges effect.
But wrapping the diffuser - and then wrapping the mid or tailcone , would for sure have a positive effect , if and only if , the result was that the average pipe wall temp
was maintained close to that as was tested on the dyno.
You could then extrapolate that, and I agree Ken , that designing , then testing pipes already wrapped on the dyno , would increase retained heat energy as well as protecting the pipe
surface from wind effects.

Edit - wrapping most of the pipe would result in one downside , backing off into a corner the surface will remain hotter for longer, this may affect off corner acceleration
helped by lower wall temp generated by heat loss from radiation.

[gamma500]

Ski-Doo has released a new model with factory turbocharged 850 E-TEC 2-stroke turbo engine:

https://www.youtube.com/watch?v=UxZY2DegTzU

https://www.ski-doo.com/2020-whats-new-ski-doo.html

I think this is the first factory turbocharged 2-stroke snowmobile.

[Pursang]

Snow is an environment where the superior power/weight of the 2-Stroke is still valued.:2thumbsup
344236

Cheers, Daryl.

[katinas]

This I tested a while ago and it is now the new setup for the TM KZ R1 engines.
What angle are you running , I tried 4 ,7 ,10 with 38 dia flat on a 54 piston.

Wob, is the reason to extend the angled part of the piston wider than squash bend on the head, or simply left equal.
Almost finished pistons for NS tests with fully open both A B, but still in doubts about the angle/flat dome dimensions. Started with 12 degrees squash and 44 mm flat center (6.5 mm squash width like on head) with 57 mm piston dia., but still left 2 mm height to play. Best would be 9 degree angle, as all my heads with this angle.

[katinas]

Honda fully covered pipes in carbon on their two cranks NSR 250 from second version in 1999 for Tohru Ukawa. This was usual Honda engineers rotation time when young group changed everything on last generation of NSR 250.
Interesting one stage diffuser on one of the Pedrosa's Honda RS250RW 2004 pipe.

[wobbly]

The tests were done initially with only a 5mm wide angle on the piston ( same width as the squish on the KZ engine ) but after a midnight dream about it
I tried going 50% area , as would be the case with a " normal " squishband.
This 38mm dia flat instantly gave better power and I was a little more comfortable machining only 1.2 mm off the top of the Vertex conical pistons.

[lodgernz]

The tests were done initially with only a 5mm wide angle on the piston ( same width as the squish on the KZ engine ) but after a midnight dream about it
I tried going 50% area , as would be the case with a " normal " squishband.
This 38mm dia flat instantly gave better power and I was a little more comfortable machining only 1.2 mm off the top of the Vertex conical pistons.

Wobbly, just to clarify:

It sounds like the "50% of area" squish band angle on the piston was wider than the previous 5mm band. True?

Did you only change the squish band width on the piston, or both piston and head?

[katinas]

Thank you Wob.
Today try 9 degrees angle but left untouched flat part from previous 12 angle and its funny, on 57 mm dia piston it gave exactly 50% or 8,3 mm. so decide start from this point.
Made different angles at B as A little further from carb so would be interesting how engine responds with little earlier pulse from A.

[wobbly]

As the KZ engines have a CIK homologated straight line ignition , if we ran 50% squish in the head - this would lead to instantaneous deto death of the piston.
The max width , that doesnt increase turbulence sufficient to effectively advance the burn speed , is 5mm , whereas a 50% squish would be 8mm.

[husaberg]

Snow is an environment where the superior power/weight of the 2-Stroke is still valued.:2thumbsup
344236

Cheers, Daryl.

You getting a lot of Snow atm in Brisbane atm?

[husaberg]

Thank you Wob.
Today try 9 degrees angle but left untouched flat part from previous 12 angle and its funny, on 57 mm dia piston it gave exactly 50% or 8,3 mm. so decide start from this point.
Made different angles at B as A little further from carb so would be interesting how engine responds with little earlier pulse from A.

How many mm offset is that pin looks about 5mm is it just the pic?

[Pursang]

You getting a lot of Snow atm in Brisbane atm?

Noooo!..... but I bet the KX500 would work for this!:niceone:

http://www.tothemoon.com/wp-content/uploads/2015/08/robbie_maddison_pipe_dream_2-645x340.jpg

Cheers, Daryl

[katinas]

How many mm offset is that pin looks about 5mm is it just the pic?

Yes , difference is 4.5 mm with 2.25 mm offset.
Piston pin dia 15 mm and circlip just from one side, other side 1.5 mm step ( 12 mm hole ).

Add this because of interesting graphs from C, with different effective petal lengths.

[oldjohnno]

https://www.youtube.com/watch?v=4HJZOBEvBMM

[Norman]

What two stroke is F1 thinking about you think? Opposite piston Achates type?

[Greg85]

There is a finite amount of energy available from the Ex port generated wave front within the pipe.
In Aprilias case the diffuser action must have been more efficient than the trapping efficiency numbers.
Thus the angles needed in the rear cone gave better power the steeper they were.
Tapering the mid section allows a bias to be generated toward scavenging ( bigger front mid section ) or toward trapping ( bigger mid section end ).
I have done several designs where scavenging needed additional help , so the diffuser needed to be steeper.
The new TM KZ engine is an example - in this case I needed to make the last diffuser way steep to generate better front side power , and the rear cone could not be as steep as it limited overev ability
thus the mid taper is reversed.

hi wobbly
I want to tell you that your R1 exhaust tm is simply a success!! I have seen R1 engines horribly modified the cylinder where the exhaust light was digging like pigs (198.5 exh timing) and the engine was still working well...no loss of low revs and overev to know what to do with it...
I bench tested the C exhaust to see if the loss was significant! the R1exhaust is catching up with a lot of preparation mistakes..good job!!

Translated with www.DeepL.com/Translator (free version)

[karter444]

Happy new year to everyone on this great informative forum
I have a question for Wobbly and anyone else keen to comment
Why is it that the kz10 range of engines seem to be the only engine that I know of that does not have water coolant flow directly over the head insert only through the casting of the head cover . this seems to me to make the engine prone to detonation especially if you are right on the edge of the correct tune .I would imagine that the top divers are only one jet away from deto
I have found 2 things happen when the head and insert are modified to allow water flow directly over the insert , the jet required to bring the egt back to the correct temp was about 4 jet sizes less and the head insert was able to be run with a 8 mm squish with no sign of deto . But due to a lack of testing and no dyno i dont actually know if these changes produce more power .
Cheers Richard

[wobbly]

The design of the R1 pipe was a very tough project to get exactly what Claudio ( the owner ) and Franco of TM wanted.
Making more power was easy , but the problem is that at much over 50Hp the engine becomes very deto prone and hard to tune correctly.
So they wanted more front side power , only a little more peak , and better power in the overev at 14,000 , so that every customer would get the benefit.
But they were adamant that if the pipe didnt suit the " factory " engines they would be happy to change those to suit.
This proved to be extremely hard to achieve - especially the need to keep peak power down , as well as achieving better overall power without getting into deto.
Using Engnod i was able to show them exactly what I was getting , without picking up the tig torch.
In the end I built 4 sample pipes , dyno and track tested those , then combined the best elements to build a sample to send to the factory.
After they dynoed the sample , all I got was a reply " send the laser patterns file please " , then DeConto and Fore track tested it and both wanted to keep it - but Franco smiled and put it back in the truck.
I truly believe that doing such a good job for them would have been impossible without Neels code to work with.

[wobbly]

Richard , yes the TM insert is hard to get your " head " around.
But put simply we want to get as much cold water thru the head as possible - for only one reason , to keep the squish band cool thus preventing overheating and deto
of the trapped end gases.
BUT , cooling the combustion chamber creates a heat sink that is directly in contact with the combustion gases.
This pulls valuable energy , of which there is only a finite amount per stroke , and puts it directly into the water - not into heating the expanding gas above the piston.
This big temp delta simply throws away Hp.
One way of cooling down the squish is to delete the 3.5mm spigot into the cylinder , and one way of keeping the chamber " hot " is to surround it with alloy, to slow down the heat rejection path.
There is another way that I have kept pretty much secret for several years now ( and 6 years of National titles ).
Keep the chamber hot , and only cool the squish area.
You can coat the chamber inner surface with ceramic ( actually illegal , but hey , who's gonna know ) or you can keep the TM system and add water cooling to the squish only.
Today's your birthday son.

[koenich]

Wob, in the 2-Stroke R&D group on Facebook you mentioned using 1 mm steel instead of 0,6 mm or 0,8 mm will loose power (sth like 2 HP for a RS125). Can you explain why?

Thermal inertia is certainly increased with t = 1mm, so it'll react slower?

[karter444]

Richard , yes the TM insert is hard to get your " head " around.
But put simply we want to get as much cold water thru the head as possible - for only one reason , to keep the squish band cool thus preventing overheating and deto
of the trapped end gases.
BUT , cooling the combustion chamber creates a heat sink that is directly in contact with the combustion gases.
This pulls valuable energy , of which there is only a finite amount per stroke , and puts it directly into the water - not into heating the expanding gas above the piston.
This big temp delta simply throws away Hp.
One way of cooling down the squish is to delete the 3.5mm spigot into the cylinder , and one way of keeping the chamber " hot " is to surround it with alloy, to slow down the heat rejection path.
There is another way that I have kept pretty much secret for several years now ( and 6 years of National titles ).
Keep the chamber hot , and only cool the squish area.
You can coat the chamber inner surface with ceramic ( actually illegal , but hey , who's gonna know ) or you can keep the TM system and add water cooling to the squish only.
Today's your birthday son.

Hi Wobbly thanks for the reply and the info . I slotted the insert cover and machined clearance around the insert so ended up cooling the whole insert . So may coat the combustion chamber as you have suggested as we really only run in open .
do you think 4 jets less to maintain correct egt with a cooled insert is about right and do you think that if you can control deto would a 50% squish area produce more power .
cheers Richard

[wobbly]

Running 4 jets leaner means that you have dramatically reduced the bsfc number , and way less energy is seen at the pipe as its disappearing into the water.
A normal 8mm wide 50% squish will have alot more unburned end gases trapped , once again not contributing to heating the expanding combustion mixture.
The turbulence created by that big squish area , is basically the same as advancing the static spark advance , and that will limit the overev capability.
The best setup I have now is the narrow 5mm squish set real close , absolute min cc with well retarded ignition.
This makes the best power on unleaded pump , and allows easy overev to 14800.
the new design of insert I came up with so as not to have to machine the cover at all.

[wobbly]

Koenich , yes many GP race teams ran 0.6 in the header and tailcone - 0.8 in the rest.
This gave an approximate equal rate of heating/cooling to the whole pipe .Seems counter intuitive but it works.
The 1mm has much bigger thermal inertia , and thus bigger surface temp deltas along the length as its being accelerated or decelerated.

[karter444]

Running 4 jets leaner means that you have dramatically reduced the bsfc number , and way less energy is seen at the pipe as its disappearing into the water.
A normal 8mm wide 50% squish will have alot more unburned end gases trapped , once again not contributing to heating the expanding combustion mixture.
The turbulence created by that big squish area , is basically the same as advancing the static spark advance , and that will limit the overev capability.
The best setup I have now is the narrow 5mm squish set real close , absolute min cc with well retarded ignition.
This makes the best power on unleaded pump , and allows easy overev to 14800.
the new design of insert I came up with so as not to have to machine the cover at all.

thanks
cheers Richard

[katinas]

This makes the best power on unleaded pump , and allows easy overev to 14800.


Its the same with less powerful Honda NS engine.
With std RON 98, after many tests with different heads (add photo, every head was changed 2 or 3 times, shape, squish, squish band width) with 57x50.6mm bore/stroke and 109 mm con rod, I always return to 6 mm squish band width for this particular engine. Strong over rev power, engine spins freely.
With 50%, lost revs and power in upper range, and no matter how piston close to head 0.7 mm or unacceptable 1.2 mm. And retarded ignition didn’t help. Only Avgaz helps.
Maybe, wider squish band needs longer conrod on unleaded 98.

[polcat88]

Richard , yes the TM insert is hard to get your " head " around.
But put simply we want to get as much cold water thru the head as possible - for only one reason , to keep the squish band cool thus preventing overheating and deto
of the trapped end gases.
BUT , cooling the combustion chamber creates a heat sink that is directly in contact with the combustion gases.
This pulls valuable energy , of which there is only a finite amount per stroke , and puts it directly into the water - not into heating the expanding gas above the piston.
This big temp delta simply throws away Hp.
One way of cooling down the squish is to delete the 3.5mm spigot into the cylinder , and one way of keeping the chamber " hot " is to surround it with alloy, to slow down the heat rejection path.
There is another way that I have kept pretty much secret for several years now ( and 6 years of National titles ).
Keep the chamber hot , and only cool the squish area.
You can coat the chamber inner surface with ceramic ( actually illegal , but hey , who's gonna know ) or you can keep the TM system and add water cooling to the squish only.
Today's your birthday son.

Wobbly, a few questions on this setup. Looking at the attached drawing is the only coolant path across the insert through the 4 channels? I assume the blind holes around the circumference are centred on the squish band?

[wobbly]

Yes , two of the channels are inline longitudinally , bottom to top on the angled cylinder , the other two are offset to line up with the rotated water exit.
The blind holes are offset outward slightly so as to maintain the stock insert step that keeps water away from the chamber area.
Note also that the top of the step is recessed slightly , to give an air gap for even more heat path insulation.

[Flettner]

So? A cast iron insert in the combustion chamber, only?

Or, why bother with a head anyway, just extra rubbish to cool.

[polcat88]

Yes , two of the channels are inline longitudinally , bottom to top on the angled cylinder , the other two are offset to line up with the rotated water exit.
The blind holes are offset outward slightly so as to maintain the stock insert step that keeps water away from the chamber area.
Note also that the top of the step is recessed slightly , to give an air gap for even more heat path insulation.


Am I correct in thinking the coolant flow path is through the crankcase then entering the cylinder to one side and above the exhaust port and then out through the head? Is the coolant directed around the exhaust duct in any way or is there just a pool of coolant around the whole duct? Asking because I wonder if the coolant below the exhaust duct actually circulates much or is a stagnant pool. I can see from Googled images that the flow through the head cover and insert is biased to flow from the intake side to the exhaust side by the inlets in the cover and then out. I cannot find a cutaway view to tell if any coolant flows over the combustion chamber in a stock setup or if it only flows around the outer diameter of the bore in the head cover.

[wobbly]

The water below the exhaust duct stops being stagnant if you drill two 3.5mm holes thru the case and thru the dimple recesses in the cylinder on an R1.
In the C model ( and older ) drill the holes thru the alloy blanking plugs in the case , and knock them out of the cylinder.
This way a small amount of water is directed out from under the duct - helping to cool it.
But nowhere near as much as it was done originally with all the water coming out of the case - up under the duct ( where it then became hot ) and overheated the transfers.

[Larry Wiechman]

Is the notion of running coolant close to the sparkplug threads no longer the prefered design?

[flyincat]

Is the notion of running coolant close to the sparkplug threads no longer the prefered design?

Wobbly - Thanks again for sharing from the bag of tricks! I logged in to ask a question about the insert, but low and behold, I get to the bottom and Larry already asked it. I'm curious about cooling the plug as well.

[wobbly]

I spent ages trying different methods to get water into the squishband area , without cooling the chamber as well.
This proved hard enough , but trying to do that as well as cooling the thread area , proved impossible to do efficiently without cooling the back side of the chamber as well.
Even with the large mass of alloy around the threads , the straight line ignition creates deto in the squishband , well before the plug body overheats and blows a hole thru the piston.
So in this application ( KZ ) the head makes more power , keeping water away completely from around the rear chamber area.
In other very high bmep engines with "proper " ignitions overheating the plug body does seem to be the limiting factor and these certainly benefit from thread cooling.

[philou]

Hello,

For a project I face a lack of space

is an asymmetry of transfers really harmful ?

Picture for example

http://www.cpindinc.com/pictures/0000/0901/DSCN0365_large.jpg

[husaberg]

I spent ages trying different methods to get water into the squishband area , without cooling the chamber as well.
This proved hard enough , but trying to do that as well as cooling the thread area , proved impossible to do efficiently without cooling the back side of the chamber as well.
Even with the large mass of alloy around the threads , the straight line ignition creates deto in the squishband , well before the plug body overheats and blows a hole thru the piston.
So in this application ( KZ ) the head makes more power , keeping water away completely from around the rear chamber area.
In other very high bmep engines with "proper " ignitions overheating the plug body does seem to be the limiting factor and these certainly benefit from thread cooling.

Could you use the insulating paint to control the areas exposed to the coolant it will not stop conduction through the aluminium but it might help, Almost like your ceramic coating of the chamber only more easy to do in the inner head cover?

[Flettner]

Is the notion of running coolant close to the sparkplug threads no longer the prefered design?

little fins around the root of the sparkplug, all water must pass this route.

[philou]

You know ?


Selachii 2 stroke carburetor. This obscure piece of 2 stroke history you have never heard of was invented in Vancouver Canada. It doesnt have a float bowl and the entire carb is made from plastic. Manufacturing started in 1978 and it uses a proprietary GE plastic called Valox 420. It has no jets and about 18 parts and that's including the screws that hold it together. One plastic needle inside the emulsion tube is the only thing that adjusts fuel. The slides are on a gear rack and open simultaneously

https://scontent-cdg2-1.cdninstagram.com/v/t51.2885-15/e35/74698406_584599739025440_4535309871617201151_n.jpg ?_nc_ht=scontent-cdg2-1.cdninstagram.com&_nc_cat=108&_nc_ohc=IE_41LdwinMAX_svTCF&oh=a17f692fe5afb5ac8042d6e7d6bcf749&oe=5EBC461C

[Peter1962]

Selachii : https://davestestsandarticles.weebly.com/uploads/4/8/4/5/4845046/hbmar78selachiicarburetors.pdf

The Selachii company was discontinued in 1983

[lohring]

That design might be perfect for small (26 cc) engines. It would flow better than the Walbro butterfly and barrel carbs. I could 3D print one.

Lohring

[husaberg]

Selachii : https://davestestsandarticles.weebly.com/uploads/4/8/4/5/4845046/hbmar78selachiicarburetors.pdf

The Selachii company was discontinued in 1983

Very little on the net i have seen thus far just the pics and the PDF
Plus the patents
https://patents.google.com/patent/CA1063454A/en

it seems work as a Gardner Lectron Possi Lake etc in that it works of a needle and taper and shape has no float bowl like a lake injetor so will need a vacuum tap or a good memory to turn off the fuel.
but the venturi and bore opens on both sides this seems pretty cool.

Edit Although in this design it appears the needle runs inside an atomizing tube all the time? not sure why this is needed?
344384

If looks could win races they would do alright

[jfn2]

Looks like a combination of the lectron carb and the MJN carb that yoshimura came out with.

[jbiplane]

I use Stihl chainsaw cylinders on my motors. Recently I increased BMEP using increased stroke 43mm instead of 40, tuning exhaust reworked port map. Immediatelly got too hot cylinders head
https://cdn3.volusion.com/ztlcx.nufyn/v/vspfiles/photos/QG09066-2.jpg?v-cache=1445604939
Old combuction chamber on photo.
https://www.picclickimg.com/d/l400/pict/162093345149_/Stihl-090-Chainsaw-Used-Oem-Cylinder-In-Good.jpg
I want take out top of this cylinders and make new cylinders heads. What could be best shape of combustion chamber to use with flat top piston diameter 66mm? Max rpm are 9000, volume 147, compression ratio 12.5 (instead of stock 10.5). I want dont overheat engine working permanently more than one hour on 75% of throttle ~12hp at 7800 rpm. Engine is in air stream of propeller. Each gramm is count. Any advice?

Do I need place thermo insulation on combustion chamber walls?

[ken seeber]

WHY DO 2 STROKES BLOW SMOKE? (or do they just want lung cancer?)

After seeing skywriting planes yesterday during the Australia Day celebrations, it got me thinking. They do it by injecting oil into the hot exhaust = incomplete combustion. I’m sure we have all chucked on an oil soaked rag or bit of paper onto a fire. If it is really soaked we see smoke. Less soaked = less smoke. Years ago at Orbital we ran a generous flow of oil into the intake of a 2 stroke 4 cyl engine carb at high load. No smoke.

Can think of a couple of reasons for smoking, but based on the above, I’ll make the statement that a typical 2 stroke premix fuel (eg 25:1), if completely combusted, does not smoke, and, in the inverse, we get smoke.

Some possible reasons being:

1. One being the short circuiting of some of the charge, escaping out the exhaust and acting exactly like a skywriting plane. One test for this might be to run an engine on straight petrol, not withstanding that the petrol that has short circuited might smoke (a bit). Anyone want to give this a try, in the interests of science of course.
2. Oil, possibly with some of the petrol lighter fractions evaporating off (due to the high engine internal temps), working its way up the bore around the piston skirt and ring and passing into the exhaust passages.
3. An accumulation in the crankcase after draining down after stopping, either escaping into the exhaust directly or around the piston as above. Can be fully or partially eliminated by a draining circuit.
4. Similar to the above, but an accumulation of oil after full or partially closed throttle on an overrun situation passing thru engine.
5. An excess of oil being delivered to the engine, eg a separate pump controlled by a properly programmed ECU. My 300 EXC TPI is an excellent smoker at startup and low loads, either as a result of shit mapping or as per reason #3 above.
6. Others?

Gotta say that I have seen many (but not all) fast race bikes down the main straight and not blowing any smoke at all. Presumably this is because the plugging pulse is so strong that all the mixture that might pass out the cylinder into the exhaust passage is fully returned and fully combusted.

It'd be nice to be able to stop it. Thoughts?

[philou]

6 : shit oil. smoke whatever we do

Ipone Samuraï for example, smoke smoke smoke. not burning :malade:

[41juergen]

Ken, I would agree on your statements. I would think that smoke (I would claim independent if 2 stroke or 4 stroke, Gasoline or Diesel) in general results from an incomplete combustion. So either because not all HC (fuel only or any mixture with (2 stroke or engine) oil) are burned or washed through into the pipe outlet (more likely on a 2 stroke, but also a bit on a 4 stroke). So incomplete combustion happens during cold start (quenching and / choke used, so very rich Lambda) and later during the charging process when the plugging in a 2 stroke is not complete (but even with a 100% plugging, the combudtion itself will be incomplete, but not worse enough to create visible smoke)...

[MotleyCrue]

Take off the entire exhaust system and run the engine if it still smokes then incomplete combustion if it doesn't smoke then it was the oil laying around in the exhaust pipe that was smoking.

[husaberg]

WHY DO 2 STROKES BLOW SMOKE? (or do they just want lung cancer?)

After seeing skywriting planes yesterday during the Australia Day celebrations, it got me thinking. They do it by injecting oil into the hot exhaust = incomplete combustion. I’m sure we have all chucked on an oil soaked rag or bit of paper onto a fire. If it is really soaked we see smoke. Less soaked = less smoke. Years ago at Orbital we ran a generous flow of oil into the intake of a 2 stroke 4 cyl engine carb at high load. No smoke.

Can think of a couple of reasons for smoking, but based on the above, I’ll make the statement that a typical 2 stroke premix fuel (eg 25:1), if completely combusted, does not smoke, and, in the inverse, we get smoke.

Some possible reasons being:

1. One being the short circuiting of some of the charge, escaping out the exhaust and acting exactly like a skywriting plane. One test for this might be to run an engine on straight petrol, not withstanding that the petrol that has short circuited might smoke (a bit). Anyone want to give this a try, in the interests of science of course.
2. Oil, possibly with some of the petrol lighter fractions evaporating off (due to the high engine internal temps), working its way up the bore around the piston skirt and ring and passing into the exhaust passages.
3. An accumulation in the crankcase after draining down after stopping, either escaping into the exhaust directly or around the piston as above. Can be fully or partially eliminated by a draining circuit.
4. Similar to the above, but an accumulation of oil after full or partially closed throttle on an overrun situation passing thru engine.
5. An excess of oil being delivered to the engine, eg a separate pump controlled by a properly programmed ECU. My 300 EXC TPI is an excellent smoker at startup and low loads, either as a result of shit mapping or as per reason #3 above.
6. Others?

Gotta say that I have seen many (but not all) fast race bikes down the main straight and not blowing any smoke at all. Presumably this is because the plugging pulse is so strong that all the mixture that might pass out the cylinder into the exhaust passage is fully returned and fully combusted.

It'd be nice to be able to stop it. Thoughts?

They smoke when they have been idling or when they are cold, AFAIK Most pollution from 4t comes from when they are cold as well.
I assume thats where most of he smoke comes from with a 2t
AFAIK the DI eventrude ones have cleaner EX than the 4t doent they?
with the 2tA lot of emissions rather than just the smoke are related to the overlapping port timings i would think.
The injection just doesn't send fuel out the ex at low revs in the first place

[TZ350]

.
Recently with Flettners help I made a center drilled crankshaft for direct bigend oiling. It was feed by a small peristaltic pump and with a small motor speed controller I could control the oil flow.

If I cranked up the oiling. On the dyno after a full noise run with no fuel the engine would run just on the oil feed to the bigend.

[Peter1962]

.
Recently with Flettners help I made a center drilled crankshaft for direct bigend oiling. It was feed by a small peristaltic pump and with a small motor speed controller I could control the oil flow.

If I cranked up the oiling. On the dyno after a full noise run with no fuel the engine would run just on the oil feed to the bigend.

Did you modify the existing crankshaft, or was it a purpose built new one ? Do you combine this with oil injection in the throttle, like the TPI engine from ktm ?

[peewee]

Hello,

For a project I face a lack of space

is an asymmetry of transfers really harmful ?

Picture for example

http://www.cpindinc.com/pictures/0000/0901/DSCN0365_large.jpg

i think those cyl have alot wrong. asymetric transfer passage. no inner and outer wall curvature. probly poor water cooling between cyl . exh passage looks very short. what engine do you have ?

[wobbly]

Peewee's cylinder is a HUGE over bored DM from CPI to fit on a Banshee bottom end.Its only real use is for open class drag racing where in Merican terms " bigger is better "
and the cubes overcome all the technical flaws.
My experience with these things is limited to the smaller Cheetah that can have a powervalve fitted.
Its intake is a CR250 that is offset outwards from center line 6mm per side.That reed is way too big for anything less than 120 Hp on petrol so I have fitted a smaller CR125 back on bore center and
picked up a minimum of 4 Hp in a 100Hp setup.
The DM has several good points about it , but would be better with a smaller bore to get somewhere near equal transfer duct areas , and some shape to the inner walls.
it also has replaceable Ex duct outlets , so making them longer and better shaped would be an easy CNC project.

[crbbt]

Just a question regarding tuning by the EGT and CHT.

If the motor isn't detonating at 660c exhaust temperature and above.
Would the next move be to increase the compression ratio or advance the timing?

[wobbly]

Depends entirely on if you have an adjustable ignition ECU.
With just the ability to wind in static advance , you will for sure pump up the midrange drive - and the added advance will drop the egt as well as reduce the overev ability.
If you then lean it down you MAY get back the overev , but that combination of extra advance and leaner jet , will also get you closer to deto - sooner.
Same with cranking up the com ratio , this also will pump up the mid , at the expense of egt and overev ability.
Again if you then lean it down , you MAY get back the rpm lost.
But with an adjustable ignition you can wind in the com , then back out some advance in the top end to bring back the egt and overev.
A win win.
If you are running a RS125 - get the April Systems switchable , curve changer ignition box , works a treat.

[ken seeber]

Vale: One unhappy IAME RL kart engine piston after an apparent coolant loss.

344483

[Frits Overmars]

344483I knew that exhaust return pulses can be strong. I didn't know they could be that strong :msn-wink:.

[TZ350]

Did you modify the existing crankshaft, or was it a purpose built new one ? Do you combine this with oil injection in the throttle, like the TPI engine from ktm ?

Drilled the original crankshaft and feed oil in from the drive end. Flettner made me a special big end pin with an oil passage in it.

20:1 fuel/oil ratio and a small peristaltic pump with variable output feeding the bigend.

The peristaltic pump can be manually speed controlled and also switched on/off as required by the digital ignition. I re-purposed the ignitions power jet control to do that.

With EFI, on overrun, I found I could turn the fuel off and pump excess oil to the bigend and the engine at small throttle openings would run on just the oil alone.

Another curiosity was that with the motor running, the large amount of air blown out through the oil feed line when it was disconnected. That is crankcase air blown back through the big end bearing and back along the oil passages. The amount of expelled air was quite surprising.

I intend continuing to use the peristaltic pump but will have it turn on for short discreet periods to just pump a small amount of oil directly to the big end. It wont have to be much to keep the big end healthy. The bulk of lubrication will be in the 20:1 Fuel/oil mix.

344484 344485 344486 344488

[katinas]

Vale: One unhappy IAME RL kart engine piston after an apparent coolant loss.

344483

Pistons damage evolution. From dome to skirt.

Add photos: without oil, together with too small clearance for 2618 alloy.

[Frits Overmars]

Drilled the original crankshaft and feed oil in from the drive end. Flettner made me a special big end pin with an oil passage in it.
344488I think I would have used spark-erosion rather than drilling. And I'd choose a somewhat simpler oil path.
But I'm sure that, as always, Neil had his reasons for doing it his way.
344500

[Splatter]

Peewee's cylinder is a HUGE over bored DM from CPI to fit on a Banshee bottom end.Its only real use is for open class drag racing where in Merican terms " bigger is better "
and the cubes overcome all the technical flaws.
My experience with these things is limited to the smaller Cheetah that can have a powervalve fitted.
Its intake is a CR250 that is offset outwards from center line 6mm per side.That reed is way too big for anything less than 120 Hp on petrol so I have fitted a smaller CR125 back on bore center and
picked up a minimum of 4 Hp in a 100Hp setup.
The DM has several good points about it , but would be better with a smaller bore to get somewhere near equal transfer duct areas , and some shape to the inner walls.
it also has replaceable Ex duct outlets , so making them longer and better shaped would be an easy CNC project.

I have been a long time reader of this thread and appreciate the knowledge that people have shared here. The more I think I know about 2 strokes, the more I find out I don't and I have learned a lot here.

I have always pondered about reed cage size and it related somewhat to your post. Did you gain the 4 Hp because the smaller cage was on center line or because of the 250 cage was too large, or both? If you run a 40mm carb with a 125 cage on a 125cc engine, does a 500cc single really need a larger cage with the same size carb? Assuming a properly designed and stuffed 500 size cage, is the increase in the reed opening "curtain" on the bigger cage better or do the larger reeds negate the advantage?

[pete376403]

Does the oil pump have any way of stopping the flow? Centrifugal force is going to suck oil through that passage once the revs come up, whether the pump is running or not

[wobbly]

Splatter , both is the answer.I first tried the smaller cage centered in the reedbox ie off center on the bore, as EngMod analysis showed that the 250 size block had way too much port area for around 100Hp.
The CR125 cage setup was worth 2Hp nearly everywhere , way more in overev.
Then I made offset plates and glued a 6mm spacer down the side to put the small reed back on bore center , as Calvin from CPI had told me the offset reedbox was a mistake in his view.
Another 2 Hp , mainly frontside up to peak.
Win , win along with being able to easily use the RS125 late model straight carb manifold.

[husaberg]

Does the oil pump have any way of stopping the flow? Centrifugal force is going to suck oil through that passage once the revs come up, whether the pump is running or not

It can only deliver what is pumped through due to the way it works
it squeezes the fluid to move it. it has multiple squeezes this a vacuum would only be able to suck one squeeze at a time it basically has a built in non return valve.
Also you can monitor oil flow and slow down the speed of the motor to suit the required delivery, as you can control the speed of the pump precisely.
<a href="https://imgflip.com/gif/3ntqqc"><img src="https://i.imgflip.com/3ntqqc.gif" title="made at imgflip.com"/></a>

[Splatter]

Splatter , both is the answer.I first tried the smaller cage centered in the reedbox ie off center on the bore, as EngMod analysis showed that the 250 size block had way too much port area for around 100Hp.
The CR125 cage setup was worth 2Hp nearly everywhere , way more in overev.
Then I made offset plates and glued a 6mm spacer down the side to put the small reed back on bore center , as Calvin from CPI had told me the offset reedbox was a mistake in his view.
Another 2 Hp , mainly frontside up to peak.
Win , win along with being able to easily use the RS125 late model straight carb manifold.

That is interesting. I guess I need to try a CR125 cage on a CR500 and see what happens. Thanks for the reply!

[wobbly]

You have three main variables . The port effective area , the fully open petal curtain area , and the 1st mode natural harmonic of the petals in bending.
The 250 cage in the Cheetah ( VeeForce ) had huge port area , that would drop the intake velocity way too much if going for less than 120 Hp.And the big , long reeds simply could not be configured to get the harmonic correct
no matter what idiotic thickness was input.

[Splatter]

You have three main variables . The port effective area , the fully open petal curtain area , and the 1st mode natural harmonic of the petals in bending.
The 250 cage in the Cheetah ( VeeForce ) had huge port area , that would drop the intake velocity way too much if going for less than 120 Hp.And the big , long reeds simply could not be configured to get the harmonic correct
no matter what idiotic thickness was input.

Is it easier to get the harmonics right with a shorter reed? On a large engine like a CR500 would it be better to use a wide but short reed cage more like a 100cc kart cage since there is plenty of room to work with in the cylinder? Assuming you could get all port area and petal curtain area numbers correct.

[MotleyCrue]

Anyone know about how much power gain is typical when switching from gas to methanol ? 10-15% more power if the exhaust pipe is not changed, just fuel flow and timing ? 15-20% if the exhaust pipe is corrected too ?

[husaberg]

Anyone know about how much power gain is typical when switching from gas to methanol ? 10-15% more power if the exhaust pipe is not changed, just fuel flow and timing ? 15-20% if the exhaust pipe is corrected too ?

Bell says


An engine burning methanol will usually show a 6-8% power increase over one
running on Avgas 100/130 (i.e., Racing Fuel 100), without any change in compression
ratio. With the compression ratio increased to its maximum, power can rise as much as
15-17%.

I say if it has poor cooling ie air cooled it will keep a higher output for longer, IE it not does fade after a few minutes or seconds.

[F5 Dave]

My experience is limited to dynoing a Norton. With the pilots too big (removed) it was cooler than a big chunk of metal had any right to be. For a thermally unstable bike that has to be an advantage. It was also toxic and you couldn't stay in the stall for long. With drilled out pilots fitted it ran hotter but still worthwhile and far more pleasant to be around. I mean, apart from the horrible noise.

[wobbly]

We did the reverse of this years ago , having to change from Meth back to petrol ( Avgas ).
On Meth it was at 18:1 compression , no extra advance anywhere , and made 48.5 Hp ( 125 TM - MX engine )
Changing back to AvGas I dropped the com to 15.8 , lengthened the pipe 15mm in the header and 15mm in the mid ( then later built a better pipe ).
Best advance curve again was as it was previously.
This setup made 43 Hp but had nowhere near the mid power , and had lost alot of overev.
I wound in some mid avdance , but this had no effect , and the only way to get the overev back was to fit a solenoid powerjet that stopped the carb
going rich over the top of the pipe.
Obviously the Methanol didnt mind going rich and kept on reving hard.
Lengthening the pipe pulled up the mid , but lost even more overev.
So the final result was a loss of 5 Hp in 48.5 = 10.3% but the real penalty was the powerband width.

[Flettner]

I think I would have used spark-erosion rather than drilling. And I'd choose a somewhat simpler oil path.
But I'm sure that, as always, Neil had his reasons for doing it his way.
344500

yes its simple,I dont have a spark eroder.

[Flettner]

Does the oil pump have any way of stopping the flow? Centrifugal force is going to suck oil through that passage once the revs come up, whether the pump is running or not

In my system, air is constantly being drawn through this hollow crankshaft, oil is delivered to this airflow at the crank intake. Air is supplied from the airfilter. TPI does not care if there is what would be effectively an air leak with a carburetor, makes for rapid oil delivery to the bigend bearing on load.

[TZ350]

Does the oil pump have any way of stopping the flow? Centrifugal force is going to suck oil through that passage once the revs come up, whether the pump is running or not


It can only deliver what is pumped through due to the way it works. it basically has a built in non return valve. Also you can monitor oil flow and slow down the speed of the motor to suit the required delivery, as you can control the speed of the pump precisely.

https://i.imgflip.com/3ntqqc.gif (https://imgflip.com/gif/3ntqqc)

Yes, a peristaltic pump has a natural stop valve at the squeeze point. At normal pressures you cant suck or blow fluid back through a peristaltic pump.

[lohring]

Anyone know about how much power gain is typical when switching from gas to methanol ? 10-15% more power if the exhaust pipe is not changed, just fuel flow and timing ? 15-20% if the exhaust pipe is corrected too ?

We did a series of fuel tests on a 26 cc race engine. It is a piston ported industrial weedeater style engine with a tuned pipe. We wanted to see if our race organization needed fuel testing. The bottom line was adding methanol and/or nitromethane didn't help power when all you could change was the needle setting. See below for a test summary. We did find in other testing that serious race fuels like VP's U1 did help performance, especially in higher compression, head button, engines.

Lohring Miller

344509

[F5 Dave]

Well, yeah you need like 2.3x the gas, so not such a broad scope test.

[TZ350]

.
On Methanol you can have a two stroke running so rich that raw liquid fuel dribbles out of the silencer. Been there done that.

On my Kawasaki F81M look alike air cooled 250cc single cylinder Classic racer I am going to blend in enough Methanol to keep the engine about 70 deg. When the temperature goes above that then a temperature controller is going to switch in an auxiliary jet to add more cooling fuel.

For me, the Methanol will be all about cooling and temperature stability in an air cooled motor. It is all about fuel blending to get the engine temperature I want. 70 deg C helps the Nitro do its job.

[pete376403]

Speedway bikes (four stroke, sorry) ran methanol because it would allow much higher compression without detonation (iirc the JAP was about 14:1, the 2v Jawa was 12 or 13:1). Both of the 2v designs had a hemispherical cylinder head and a high dome piston and ran a lot of ignition (magneto) advance. The higher comp gave better acceleration. At one time in the UK there were test with petrol powered bikes, obviously they had to lower the compression, petrol reportedly gave better power but the bikes didnt accelerate as well (speedway is all about acceleration rather than top speed)

[lohring]

Our fuel testing was done to show that there's no magic in fuel for our industrial engine based engine classes where the engine was setup to run on gasoline. Open class engines are a different animal. We are currently considering adapting one of those to run on E85. We believe more power should be possible with the right head button, Powerspark ignition, a larger carb, and the right pipe. We just need to get a ruling that it's considered "pump gasoline" as specified in our rules.

Lohring Miller

[andreas]

The 250 DEA kart cylinder or Rotax dito, are there any portmaps, measures, photos, pipe drawings or other useful information circulating?

[SwePatrick]

The huge knowledge in this forum might have the answer to my question below.. ;)

A complete without carbs and exhaust TDR250 engine (1kt) , how many kg´s is it?
Need to know for a shipping project.

Rgds
Patrick

[dgee]

The huge knowledge in this forum might have the answer to my question below.. ;)

A complete without carbs and exhaust TDR250 engine (1kt) , how many kg´s is it?
Need to know for a shipping project.

Rgds
Patrick

Just under 30kg according to my cheapo scales.

[SwePatrick]

Nice,, thanks =)

[F5 Dave]

From RGV forum. That's quite some reed stuffer. Not sure I'm really convinced, but perhaps if, like in the CPI example Wob gave before, the Reed area is too large, maybe this sort of stuffer would be beneficial?

[speedpro]

I wouldn't be surprised if that worked. It is surprisingly similar to one I made ages back right down to the centre splitter with the curved leading edge which I also had a nice radius on. My idea was to keep the cross-sectional area as constant as possible from the carb right up to the petals. It went OK and was distinctly different sounding to all other stuffers I tried

[Grumph]

.
On Methanol you can have a two stroke running so rich that raw liquid fuel dribbles out of the silencer. Been there done that.

On my Kawasaki F81M look alike air cooled 250cc single cylinder Classic racer I am going to blend in enough Methanol to keep the engine about 70 deg. When the temperature goes above that then a temperature controller is going to switch in an auxiliary jet to add more cooling fuel.

For me, the Methanol will be all about cooling and temperature stability in an air cooled motor. It is all about fuel blending to get the engine temperature I want. 70 deg C helps the Nitro do its job.

Don't think you can do it, Rob. The fuel regs as they stand only recognise "petrol" - matching a set of standards in the book with an allowable oil content.
And "methanol" - again matching a spec in the book, again with an allowable oil and solvent content.
Blends are apparently non-compliant. I've asked the MNZ tech steward and he's in agreement, the book makes no provision for blends.

Personally, it pisses me off as the Post Classic regs are supposed to reflect what was in force at the relevant period. Nitro was in common use as were meth based blends.

[TZ350]

.
Hi Grumph. Good point I had not thought of that. Totally unexpected interpenetration of the Methanol fuel rule.

With Meth I was basically just heading down the same path that I did back in the 70's. Fuel blending to get the air cooled engines to run at the right temperature was a must. Interesting that some official would through absolute technical ignorance resort to a literal interpenetration. Not ignorant I guess, just interpenetrating the rules as written. No surprise I suppose, You and I have seen enough out of touch bureaucratic bull shit in our time.

It won't stop me though as a water test for an acetone methanol blend will come up the same as 100% methanol. Acetone and methanol have similar reactions to water. A hygrometer much the same. I ran my air cooled racers on a 50/50 mix of acetone and methanol back in the day.

Acetone has a higher octane rating than Methanol and cooling property's about half way between Av gas and Methanol. Acetone is a great fuel in itself. If I have to, I can blend in some Nitro to bring the specific gravity of the fuel up to spec. This whole thing brings back happy memories of cat and mouse tussles with tec inspectors back in the day. Love it.

[Grumph]

I'd still advise caution. As I see it, your problem is that you won't be dealing with MNZ officials - the current guys are experienced and reasonable to deal with - but Classic Register officials....I seem to remember a register member being banned for using a "rocket fuel" drum to carry his 100 octane.
No proof of use of the illegal fuel, just the drum. No appeal.

The other thing likely to happen is meth being banned as a fuel for 2 strokes again - as it was in the aftermath of the Cal Rayborn fatality.

[pete376403]

http://www.2t-racelab.com/2012/02/kawasaki-x-09.html Neat looking, unique engine configuration but in the end not fast enough

[ken seeber]

Here’s a pic of a TM 100 cc reed kart engine with piston & cyl removed. Direct drive, air cooled and used for sprint kart racing.

344665

Someone has put a lot of time into the bottom end, blending out the cases and, interestingly, radiussed the inside edge of the crank webs. Not sure if this might be of any benefit, but could/does offer the following:

1. Increases crank case volume
2. Lightens the crank and reduces its flywheel effect (2nd moment of mass). The opposite of what has been done elsewhere.
3. Reduced the Cd of gas flow into and out of the crank cavity, particularly as this is a vertical reed engine.
4. Perhaps improves the lateral flow out of the crank cavity towards the transfer entries
5. Adds remote volume, at the bottom of the case cavity, maybe making the transfer of this extra volume less accessible.

Anyone seen this and would it be advantageous in certain applications? I do know there are a shitload of other variables involved, that need to be taken into account. I also appreciate that there are no simple universal answers for 2 strokes.

[TZ350]

I'd still advise caution.

Thanks for the heads up.

[SwePatrick]

Another question:

Is there some way to remove nicasil without machining?

Rgds

[husaberg]

Another question:

Is there some way to remove nicasil without machining?

Rgds
I thought it gets stripped with nitric acid?
Yow ling has done it.

[wobbly]

Ken , here are some thoughts on the TM100 kart mods.
The crank radiusing probably has more positive effect on the intake Cd as alot of the flow from the vertical reed orientation is directed straight into that area.
In a 100cc kart engine , the reduction in inertia would have more positive effect on acceleration , than the negative effects of the in cycle speed variation reducing transfer STA , as its
easy to get sufficient areas with the low bmep produced.
This type of mod was done many years ago on many factory tuned 100cc reed engines I have seen.

[Flettner]

Ok, Im going to ask here, who has a set of late modle YZ 125 cases laying around? So I might measure them up. No asking questions, ok. You can have them back when Im finished.

[anglia4]

Stinger question:
Due to packaging and the location of my muffler (under seat) my stinger is ending up longer than desired.
Would it help keep things in order if I step it back up by a tube size or two after the designed stinger length?

[F5 Dave]

Research posts on nozels at baffle end and make the Stinger bigger.

[anglia4]

Thanks for the search direction ;)

I’ve been reading this thread for a couple of weeks now but haven’t even cracked page 100 yet! :killingme

[TZ350]

.
nozzle site:https://www.kiwibiker.co.nz/forums/showthread.php/86554-ESE-s-works-engine-tuner

Use the google "site:" search term to find what you need. Cut and paste the search line above to find the posts on the ESE thread that talk about stinger nozzles.

344712

[husaberg]

.
nozzle site:https://www.kiwibiker.co.nz/forums/showthread.php/86554-ESE-s-works-engine-tuner

Use the google "site:" search term to find what you need. Cut and paste the search line above to find the posts on the ESE thread that talk about stinger nozzles.

344712
I posted these the other day in another thread.
https://www.kiwibiker.co.nz/forums/showthread.php/86554-ESE-s-works-engine-tuner?p=1131099423&highlight=stinger+nozzle#post1131099423

https://www.kiwibiker.co.nz/forums/showthread.php/86554-ESE-s-works-engine-tuner/page218?p=1129954861#post1129954861

https://www.kiwibiker.co.nz/forums/showthread.php/86554-ESE-s-works-engine-tuner?p=1129955411#post1129955411

https://www.kiwibiker.co.nz/forums/showthread.php/86554-ESE-s-works-engine-tuner?p=1130089030#post1130089030

https://www.kiwibiker.co.nz/forums/showthread.php/86554-ESE-s-works-engine-tuner?p=1130209099&highlight=nozzle#post1130209099

[edgefinder]

One thing I see in Ken's picture of the TM 100 is the big end bearing will be as cool and well lubricated as possible, not a weak link but ready for a hard life

[husaberg]

Just me?........I find that intake very organic in shape.
344766

[wobbly]

Absolutely not just you.Anyway its not a tree its a bush.

[jbiplane]

Thik it could be interesting for local comunity?

https://www.youtube.com/watch?v=aovQguKPG4A&t=19s

[SwePatrick]

Well,, I got my TRD250 engine at home finally.
It is an object, not worthy taking pics on yet, rust and corrosion everywhere, but salvagable.

I got this question thou, is it possible that any YZ125 cylinder might fit on it?
The engine is an 1KT/2MA.

Rgds
Patrick

[F5 Dave]

The YZ barrel with no cast in liner of course is small and light. If you don't have the carbs fitted to the TDR engine it should fit just nicely above the gearbox area with little chance of falling off.
No problem, thank me later.

[SwePatrick]

I was looking at -93 YZ cylinders, they had the same bore stroke.
And topdeck surface looks very similar as the TDR heads surface.

They got as std 56/50 bore/stroke
As my classrules says max 212cc i´m thinking about put thicker liners in them and run 50/50 bore/stroke and get ~196cc and a lot of material to bore if needed.

[husaberg]

I was looking at -93 YZ cylinders, they had the same bore stroke.
And topdeck surface looks very similar as the TDR heads surface.

They got as std 56/50 bore/stroke
As my classrules says max 212cc i´m thinking about put thicker liners in them and run 50/50 bore/stroke and get ~196cc and a lot of material to bore if needed.

There was a 400cc TZR 1kt done with DT200 Cylinders and a stroked crank
A lot of work to get it all to fit esp te heads the best cylinders to use are WR200 as they are supposed to be triple EX port.

https://www.kiwibiker.co.nz/forums/showthread.php/86554-ESE-s-works-engine-tuner?p=1130346885&highlight=tzr400#post1130346885
https://www.kiwibiker.co.nz/forums/showthread.php/86554-ESE-s-works-engine-tuner/page550

[SwePatrick]

Yes,, but i cant have above 212cc total

[husaberg]

Well,, I got my TRD250 engine at home finally.
It is an object, not worthy taking pics on yet, rust and corrosion everywhere, but salvagable.

I got this question thou, is it possible that any YZ125 cylinder might fit on it?
The engine is an 1KT/2MA.

Rgds
Patrick


Yes,, but i cant have above 212cc total

Okay it was a bit unclear, so why choose a 2 cylinder 250cc engine? and then have to destroke or sleeve 2 cylinders.
If its a 200cc engine in total and you want it to be a twin, i would sugest following TZ350 lead in destroking like he did with his GPNSR100, not ideal, but far less costly mods.
ie no sleeve and replate x2

[SwePatrick]

I´ve got THIS engine now, i won´t buy a totally other one, let´s make the best of what i´ve got.
And i find it very good(and easy) to go down in bore size and make it square.

I have also destroked a KX250 engine with some good results, but i want to test a new way.

[TZ350]

.
One advantage of de stroking a two stroke engine is that it automatically increases the blow-down-time-area for extra power and rpm without having to do any porting to the cylinder.

Shortening the stroke means the crank will rotate through more crank angle degrees going from exhaust opening to transfer opening.

[lodgernz]

.
One advantage of de stroking a two stroke engine is that it automatically increases the blow-down-time-area for extra power and rpm without having to do any porting to the cylinder.

Shortening the stroke means the crank will rotate through more crank angle degrees going from exhaust opening to transfer opening.

No porting...except bringing the exhaust port(s) and the transfers closer together to compensate for the shorter stroke.
Oh wait...that will reduce the blowdown STA...

[SwePatrick]

.
One advantage of de stroking a two stroke engine is that it automatically increases the blow-down-time-area for extra power and rpm without having to do any porting to the cylinder.

Shortening the stroke means the crank will rotate through more crank angle degrees going from exhaust opening to transfer opening.

I´m not destroking this engine.
I was thinking to get more correct bore for the stroke i already have.
This engine is oversquare as oem.
Now i´ll decrease the bore to make it square.

[TZ350]

I got this question thou, is it possible that any YZ125 cylinder might fit on it?

If the cylinder does not bolt straight up and if you wanted to. It is possible to move the stud holes a bit.

We screw and glue a 20mm length of alloy into the old stud hole. Then use the cylinder as a guide and drill and tap new stud holes. Re drill one hole first and use it to hold the cylinder down while you spot the other holes. It can all be done with a hand drill. Nothing fancy required.

344818 Kawasaki F8 350. Re-positioned cylinder studs to fit a Suzuki TS250 cylinder.

344819 Suzuki GP100. Re-positioned cylinder studs to fit a Honda NSR cylinder.

The alloy plugs in the old stud holes can be seen next to the new cylinder studs.

[SwePatrick]

If the cylinder does not bolt straight up and if you wanted to. It is possible to move the stud holes a bit.

We screw and glue a 20mm length of alloy into the old stud hole. Then use the cylinder as a guide and drill and tap new stud holes. Re drill one hole first and use it to hold the cylinder down while you spot the other holes. It can all be done with a hand drill. Nothing fancy required.

344818 Kawasaki F8 350. Re-positioned cylinder studs to fit a Suzuki TS250 cylinder.

344819 Suzuki GP100. Re-positioned cylinder studs to fit a Honda NSR cylinder.

The alloy plugs in the old stud holes can be seen next to the new cylinder studs.

Yes,, i´ve done that procedure several times, but it would be very cool if they mounted directly, if not i might run for some more aggressive cylinders and not having to port them.
Like Roost 100cc or 2fast 100cc

[Haufen]

I´m not destroking this engine.
I was thinking to get more correct bore for the stroke i already have.
This engine is oversquare as oem.
Now i´ll decrease the bore to make it square.

I am not sure I understand. Are you above the displacement limit for your class at the moment and plan to aim for the maximum allowed displacement by decreasing the bore?
Or are you at the allowed maximum displacement now and would afterwards have an engine smaller than allowed but more square?

[katinas]

I am not sure I understand. Are you above the displacement limit for your class at the moment and plan to aim for the maximum allowed displacement by decreasing the bore?
Or are you at the allowed maximum displacement now and would afterwards have an engine smaller than allowed but more square?

The answer is in previous post about SwePatrick new project TZR 250cc 56/50 bore stroke engine.
"As my classrules says max 212cc i´m thinking about put thicker liners in them and run 50/50 bore/stroke and get ~196cc and a lot of material to bore if needed." until max 51.9mm bore for 212cc rules if liner wears out or damaged.

[Haufen]

The answer is in previous post about SwePatrick new project TZR 250cc 56/50 bore stroke engine.
"As my classrules says max 212cc i´m thinking about put thicker liners in them and run 50/50 bore/stroke and get ~196cc and a lot of material to bore if needed." until max 51.9mm bore for 212cc rules if liner wears out or damaged.

got it, thanks!

[wobbly]

My take SwePatrick would be to go square as you are planning - gives real rev potential with the already short stroke ,plus easy optimum STA values , but then fit alloy liners that are easy to port.
Weld them in at the top and bottom ( easy ) then Nicasil them.
Much better heat transfer and no wear issues with resulting overbores.

[ken seeber]

Corking crankshafts. Need to “stuff” a crankshaft. 4 holes at Ø24. Champagne corks seem to be the go as the size is ok and it’s not even a problem getting them. It’s a low speed mundane application.

So after the heating them up in hot water so they’re soft and then pressing them in, there is a question. Should they be treated in any way (eg a sealant) to prevent fuel/oil attacking the cork?

[husaberg]

Corking crankshafts. Need to “stuff” a crankshaft. 4 holes at Ø24. Champagne corks seem to be the go as the size is ok and it’s not even a problem getting them. It’s a low speed mundane application.

So after the heating them up in hot water so they’re soft and then pressing them in, there is a question. Should they be treated in any way (eg a sealant) to prevent fuel/oil attacking the cork?

Soak em in alcohol for a year...........:whistle:

[wobbly]

TM MX cranks use cork and a thin layer of two pot epoxy is used to seal over the exposed surface.

[Haufen]

Happy New Year to everyone!

Anyone else going to attend the two-stroke engine conference in Paris mid February?

2-stroke engine conference (http://di2-stroke-engine.ifp-school.com)

Edit: you can also download the 2018 presentations here (https://drive.google.com/drive/folders/1lIR2GrILqeNl6lF0Pp_Gsp7R1OTJQRdm)

The presentations of this year's event are available for download now - click this text (https://drive.google.com/drive/folders/1-r_V-wLRc9Lee5HnZgehoGwFXLrhjPH9).

[Peter1962]

The presentations of this year's event are available for download now - click this text (https://drive.google.com/drive/folders/1-r_V-wLRc9Lee5HnZgehoGwFXLrhjPH9).

Thank you for the link. The presentation in session 3 about the opposed piston engine (Turner and Vorraro) whas very interesting !

[Niels Abildgaard]

The presentations of this year's event are available for download now - click this text (https://drive.google.com/drive/folders/1-r_V-wLRc9Lee5HnZgehoGwFXLrhjPH9).

Thank You for link.
The paper from Brunel university about opposed piston two stroke mentions a lapsed 2013 patent from lotus about having a generator on each crankshaft and no mechanical connection.
I made and ran such a system in ca1994.
There is a gentleman from Austria Graz who find that a side-exhaust-valved two stroke can be awfull good for range extension of electric cars.
I described it around may 2014.
It proves that being an inventor is not getting You fame and fortune but it is a nice feeling anyway.

[husaberg]

Thank You for link.
The paper from Brunel university about opposed piston two stroke mentions a lapsed 2013 patent from lotus about having a generator on each crankshaft and no mechanical connection.
I made and ran such a system in ca1994.
T.

I am confused by the mention of the lotus engine
As magnetuic drives have been around for years, my aquarium had one in the 90's.
Was it done somehow differently?


https://www.youtube.com/watch?v=HHbqua7hqko

[Flettner]

Uniflow, so last century.
Three main issues as I see it.

scavenging system
combustion chamber
exhaust piston thermal loading.

Uniflow scavenge, who would have thought.

[katinas]

Thanks for winter without the snow, for the first time, it is possible to test many things on the road.

With direct to transfer intake scheme on Honda NS engine some very interesting engine reactions to some changes. Too many tests with different combination and it is very complicated transform all things in words, so I just put main things in graphs, but maybe it looks even more complicated.

Exhaust pipe and cylinder head is the same for all main tests.
In general, the biggest surprises was Type 2 mid range torque from 6000 rpm . with the exhaust pipe that mainly works from 9000 to 13000 rpm. Never feel that power at lower revs with this engine before, feels like with exhaust power valve. But Type1 with side reed petals always strongest at higher revs, especially in range from 12500 to 13000rpm. Thicker side reed petals works without any damage (0.5 mm)
From other engine reactions, looks like for midrange torque, it is very important at witch point intake tunnels is connected to transfers ports, as pressure fluctuation accumulated pressure at both transfer port ends. Maybe this explains very low Rygeriser type torque at midrange (not only because of reduced intake capacity as I think before).

Tested with two different cylinders and three different pistons.
Cylinders
1. The same as previous posted with bronze liner and side reed petals
2. Original with nicasil plating, just intake windows are fully blocked with Loctite EA3479A ( add photo), all intake flow through enlarged side boyesens tunnels. Additional carbon plate, with reed petals on it, between cylinder and crankcase, as very complicated to add side reed petals on std cylinder because of lower side cuts.
Pistons
1. Special with deep side cuts and wide exhaust side skirt for two or three exhaust windows
2. Special with deep side cuts and narrow exhaust side skirt for one exhaust window
3. Normal piston ( from CR 125 2006 big bore 57mm)

[katinas]

With additional intake widows under main A,B it is possible to use normal piston, so no needed spec custom piston with side pockets. With these widows it is possible to use wide, two or three exhaust ports.

[Norman]

With additional intake widows under main A,B it is possible to use normal piston, so no needed spec custom piston with side pockets. With these widows it is possible to use wide, two or three exhaust ports.
Very interesting. Maybe combination carb diameter, inlet length and total volume in the transfer channels are very important in your concept. Too big transfer channel volume will not create enough suction and inlet air speed to allow piston to compress air at the same time as flow continues through inlet. Too small transfer channel volume, too big carb diameter, will not keep air speed up into transfer channels when piston moving down to compress, giving less total air in. At higher rpm relatively small transfer channel volume holds back the exhaust from entering too deep into transfer channels but the exhaust pressure compresses the fresh air there. While some exhaust is occupied with compressing the transfer channels the rest is going out through exhaust port and most of the fresh air hold back and will later not have time to escape out. A three windowed exhaust port should maybe be a bit lower then? Just a thought..

[Haufen]

Thanks for winter without the snow, for the first time, it is possible to test many things on the road.


Thanks for the interstign insights, katinas!
It would be really really cool - and I guess pretty helpful for your research too - if you had a dyno!

In case you need assistance building one yourself, let me know.
You can also use a road dyno, which gives pretty accurate results if you use the same part of the road for all of your tests (numbers will be relative, but the shape and if it's better than before is what counts anyways).

click here for a link to a free road dyno, description below (http://atom007.heimat.eu/tmt/gsf_dyno.html):


GSF Dynamometer software in combination with a commercial sound-recorder allows for making power/torque curves of a motorcycle (or car). Dyno runs are done (recorded) on the street and analysed on the PC at home. Dyno runs are essential for tuning and correct jetting of the carb. Here you found the minimum-cost dynamometer. All you need is to download the dyno software, a sound recording system and I suggest to build the voltage divider as described below.

[Frits Overmars]

... It would be really really cool - and I guess pretty helpful for your research too - if you had a dyno! ....You can also use a road dyno, which gives pretty accurate results if you use the same part of the road for all of your tests.... click here for a link to a free road dyno, description below (http://atom007.heimat.eu/tmt/gsf_dyno.html):I fully agree :niceone:

[katinas]

Very interesting. Maybe combination carb diameter, inlet length and total volume in the transfer channels are very important in your concept. Too big transfer channel volume will not create enough suction and inlet air speed to allow piston to compress air at the same time as flow continues through inlet. Too small transfer channel volume, too big carb diameter, will not keep air speed up into transfer channels when piston moving down to compress, giving less total air in. At higher rpm relatively small transfer channel volume holds back the exhaust from entering too deep into transfer channels but the exhaust pressure compresses the fresh air there. While some exhaust is occupied with compressing the transfer channels the rest is going out through exhaust port and most of the fresh air hold back and will later not have time to escape out. A three windowed exhaust port should maybe be a bit lower then? Just a thought..


…..and position, where intake tunnels is connect to transfer ports, must be at the point where average positive pressure in trans ports is the lowest. Maybe intake tunnels, from main reed, must be placed in the “half moon”- between cylinder wall and transfer port inner radius wall, where Jan added cooling.
With RGV engine closed bottom crank space (without side reeds, add photo), testing was done with another type, its like intake tunnels added at the lower, say starting point of transfer port. From 8000 rpm engine stopped and only first gear overcome 8000-10000 rpm dip. Only two16 mm holes on separator sides that depress crankcase, eliminate dip.

Haufen, Frits I fully agree too. But at the moment I am fully illegal on the road. No technical inspection, no insurance, so I feel like a bunny on the road. One eye always ready to recognize police car. But now, as my moto gp commentator job postponed, I have more time finally to travel just 250 km to put all the stuff on my friend's dyno.

Other interesting thing. Accidentally, with spark plug 0.9 mm gap, found how piston/head clearance changed on this particular engine.
Very low rpm, piston just touching ground electrode – gap 0.8 mm
Not warmed engine, shortly to 14000 rpm – gap 0.5 mm
Then full load on the road – gap 0.2 mm (with usually unstable work from low to mid range with such small gap)
So difference is 0.6 mm from piston center, maybe piston squash area approached a similar distance. Maybe this explains why this engine spins freely with no less than 0.9 mm squash height or 0.3 mm that left with heat and revs.

[F5 Dave]

Linisher meets piston
Done that before. Although less subtle on 50. Closed gap completely :lol:.

Having extensive dyno use and much experience with one racebike that was always on it, then raced I figured I had a pretty well calibrated rear end. But it made me look silly several times, fortunately with no audience.

[Niels Abildgaard]

Thanks for the interstign insights, katinas!
It would be really really cool - and I guess pretty helpful for your research too - if you had a dyno!

In case you need assistance building one yourself, let me know.
You can also use a road dyno, which gives pretty accurate results if you use the same part of the road for all of your tests (numbers will be relative, but the shape and if it's better than before is what counts anyways).

click here for a link to a free road dyno, description below (http://atom007.heimat.eu/tmt/gsf_dyno.html):

'Very,very elegant method(If I have understood it correctly).
It can even be made absolute if You make two runs with different mass and same air resistance.
A couple of old accumulators in rucksack?

[Dominator Motorsport]

Gedday Guys,

New member to the forum after being introduced by Ken Seeber. I first met Brett and Ken Seeber of Strike Products through my engineering work experience, and ever since, I’ve become a 2 stroke man. Since then, given that almost all engineering in Perth is resource based, I’ve moved to working in Oil and Gas. Which I find unfortunate as I’m an M6 and M8 kind of guy, rather than the M24’s or greater you may find on oil rigs. But I still get my 2 stroke fix through karting, yet another great discovery that Ken and Brett showed me. Which brings me to my questions…

I’ve recently acquired an old TM KZ10 for something to tinker with. I must say this forum has been gold for advice, especially Wobbly’s wise words. Ken and Brett have also been champions (head like a spark plug) with their top tips and for letting me use their equipment. I’m taking it in smaller steps for now, but so far I’ve worked the ports, deepening the auxiliaries based on some of Wobbly’s posts. The other steps will be some odd cooling jobs, including the cooled head insert, drillings between the crank cases and cylinder to get some flow around exhaust, and a few other small details. Finally, I’ll top this off by running a vortex piston with a 38mm flat on top. Undoubtedly small jobs compared to the likes of the 2 stroke legends in this forum, but its somewhere to start.

My question for you guys is what would be your thoughts on radiusing the web above the crank region? So far I have two opinions on this, first being radiusing both sides for a greater net inlet flow, which must be a good thing? But my second idea is to just radius the bottom, thinking that restricting flow into, but not out of the crank region, will help concentrate the fresh charge towards the transfers? Currently I am more inclined to the second option due to the fact the shroud/web is there in the first place, and partly chamfered on the bottom only. Otherwise looking at extremes, why not remove the shroud entirely?

Any wise words would greatly be appreciated.

Thank you,
Dominik

344946

[katinas]

My take SwePatrick would be to go square as you are planning - gives real rev potential with the already short stroke ,plus easy optimum STA values , but then fit alloy liners that are easy to port.
Weld them in at the top and bottom ( easy ) then Nicasil them.
Much better heat transfer and no wear issues with resulting overbores.

ICBM alloy liners www.ibg.co.jp
https://page.auctions.yahoo.co.jp/jp/auction/e397845803
https://www.youtube.com/watch?v=NJsU08ye6HA

[wobbly]

Removing the shroud is dumb - the cranks perifery is rotating against the reed inflow , so the shroud restriction is there specifically to reduce the interaction between the crank wheels and the incoming charge.
Secondly the machined " duct " opposite the boost port is there to direct a tangential exit flow from the crank' s OD boundary layer , out from under the shrouds trapping action, toward the piston and transfer duct entries.
Thus I believe any attempts at enhancing flow into or outward from the shroud slot is doomed to abject failure.
But hey its a motherfucking twostroke , so everything I have just said could be complete bollocks - and should be treated with the howls of derision it deserves.

[TerraRoot]

spoke about this last year, i of course have done shit.


https://youtu.be/u7cwAe5mLig

crazy they used the same engine i had/have planned.
could they have done the cylinder any worse? no. it does run tho!

[husaberg]

spoke about this last year, i of course have done shit.


https://youtu.be/u7cwAe5mLig

crazy they used the same engine i had/have planned.
could they have done the cylinder any worse? no. it does run tho!

If you richen up the pilot, the needle and mainjet enough, its far far easier, not to mention cheaper to convert a 2 stroke into a 4 stroke.:innocent:

[ken seeber]

Hello, anyone there ???

Years ago 2 strokes were often criticized for blowing up. Less so these days … :niceone:

344986

[WilDun]

Hello, anyone there ???

Years ago 2 strokes were often criticized for blowing up. Less so these days …

Good to see you still there Ken, - BTW was that bike a Bridgestone? (before it disappeared through the roof).

[Frits Overmars]

Good to see you still there Ken, - BTW was that bike a Bridgestone? (before it disappeared through the roof).Nah, it's a Kawasaki 250cc Samurai or its bigger brother, the 350cc Avenger. The two models could be distinguished by the slightly different shapes of their cooling fins, but that's hard to tell in the above picture. But why do you ask? Are you too young to know or too old to remember? I always thought you're older than me....:confused:

[WilDun]

Nah, it's a Kawasaki 250cc Samurai or its bigger brother, the 350cc Avenger. The two models could be distinguished by the slightly different shapes of their cooling fins, but that's hard to tell in the above picture. But why do you ask? Are you too young to know or too old to remember? I always thought you're older than me....:confused:

Too old to remember! (76) - I should've known better cos i was racing a T20 Suzuki leading a Honda 305? and one of those (350cc) Kwakers at a street circuit here - all very close, and after a few laps I lost it and slid off, the two bikes behind did the same and next thing I was standing looking down at two very injured guys (one had a broken collarbone and was saying nothing and the Kawasaki guy (who had a footrest embedded in this achilles tendon was calling me some very nasty things (I think he was just pissed off because he saw that my 250 had the legs on his 350!) - ... or maybe not! - anyway, I escaped with some gravel rash and bruises! - all great fun really! - hope you guys are all ok! - we're all in it together now!

[Pursang]

hope you guys are all ok! - we're all in it together now!

Best wishes to Everyone who follows ESEswet, and your families - Stay safe & healthy.

If there is a tiny silver lining...Lack of free Time is no longer a reasonable excuse for not completing all those outstanding projects in the workshop :yes:
(and around the home) :yawn:

Cheers, Daryl

[WilDun]

Best wishes to Everyone who follows ESEswet, and your families - Stay safe & healthy.

If there is a tiny silver lining...Lack of free Time is no longer a reasonable excuse for not completing all those outstanding projects in the workshop :yes:
(and around the home) :yawn:

Cheers, Daryl

Good to see you still around Daryl - you Aussie guys sure had a double whammy this year!

[wobbly]

Send me a PM with your email - I will help.

[TZ350]

Yesterday I bought the engmod2t software.

Hi FRRRIOLI, welcome and its great to see you have got a copy of EngMod2T.

There are some sample files that come with EngMod. What I often do is use them and make changes to suit the engine I am modelling.

Each page of the 2T modeling program has an option to save the file with a different name. I do this first, then make changes to the new file. That way the original is preserved.

345017

The EngineMod2T comes in four modules, as seen in the attached picture below. Step 1 is to create the model. Step 2 is to simulate the model and Steps 3 and 4 are to look at the results of the simulations.

345016

[lodgernz]

Question about EngMod2T:
In the reed valve screen, some of the data required is difficult to determine, or so it appears to me.
For example, Young's Modulus and Density of petal material, and the node damping factors.
I categorise my petals by the force required at the leading edge to open them to the stops.
Is there any way I can use this data to answer the above questions?

[F5 Dave]

Hiya new guy. You won't be able to send a PM until you have a certain number of posts.

[jbiplane]

Milling new piston for kreuzcopf engine (rougly Ryger)

https://youtu.be/H3tivA0M8QI
76mm external diameter.
https://reaa.ru/attachments/piston-198-jpg.424254/
Hope with new pistons engine would start easier than now.

[wobbly]

Lodger - reed stiffness is one of the hardest elements to model correctly - mainly as its not possible to enter added backups ( continuously varying with lift ) influences on the petal action.
In short the only way to do this , and get realistic results , is to use the modulus defaults - then adjust the petal thickness to get close to the recomended first mode rpm.
Then watch the intake screen during a sim run.
One of two scenarios will happen , if the input thickness is too thin , the petal tip will either hit the stop or overbend.
In this case the lift height shown will vary hugely from one iteration to the next ie the output is unstable.
If the thickness is too big , the max lift will be limited , and power drops due to insufficient curtain area.
Max lift should generally be no more than 1/3 the free length.
If you adjust the thickness to just short of hitting the stop , or use the 1/3 guide to be close to unstable , this will be the optimum petal stiffness .
This method in reality only takes out any " bad " influence the reed may have on results - it doesnt tell you the optimum reed dimensions.
So sadly , the only way to actually get the best reed setup is hours of dyno testing.
Sim results dont show any output like using a gram scale to determine tip lift pull pressure.
I use a small digital gram scale to point me in the right direction on stiffness when changing the main petals thickness and or backup pressure /length.
Then going too stiff , will eventually limit top end , or going too soft will eventually ruin the mid.

[lodgernz]

Thank you Wobbly. Good info.

[F5 Dave]

Sorry I cant help with the hours of dyno anymore, would have been a good way to self isolate in a safe smokey environment. Might attract attention though. Strangely those sheds it was housed in haven't been knocked down yet. Oh well.

I think it's like 10 posts to get PM privilege .

[lodgernz]

Sorry I cant help with the hours of dyno anymore, would have been a good way to self isolate in a safe smokey environment. Might attract attention though. Strangely those sheds it was housed in haven't been knocked down yet. Oh well.


Yes, having access to a dyno and to your expertise was a great privilege, and I'm eternally grateful. Pity it had to end
Still, as you say, the cops would have been around in no time in this lockdown environment.

[lodgernz]

I need advice again please 2T friends:

My NS50F (same as NSR50, etc) has double-lipped seals on each end of the crank, like every other 2T, but on the right-hand (drive side) seal, one of the lips is Viton, the other isn't.
My workshop manual helpfully gives no advice, but I suspect the Viton lip goes inwards since that side is more exposed to heat and fuel than the outside.
I'd appreciate any confirmation or contrary opinion please.

[lohring]

So how does this look as a two cone drive? Attached is a sketch of the components. I'm using a standard ball bearing between two aluminum cones. It rides on a carriage guided by a linear rail and adjusted with a screw. There's a slight interference fit between the cones and the bearing. The bearing is in the 1:1 position with an approximately 1.5:1 position close to the other end.

Lohring Miller

[Haufen]

I need advice again please 2T friends:

My NS50F (same as NSR50, etc) has double-lipped seals on each end of the crank, like every other 2T, but on the right-hand (drive side) seal, one of the lips is Viton, the other isn't.
My workshop manual helpfully gives no advice, but I suspect the Viton lip goes inwards since that side is more exposed to heat and fuel than the outside.
I'd appreciate any confirmation or contrary opinion please.

If one of the two lips has a spring, then this one is closer to the crank center.

[TZ350]

.
My experience with Yamaha RD and TZ crankshaft seals that had (I think it was Teflon) coated lips, was that the coated lip faced into the crank case.

The Yamaha seals had springs on both lips. The mag side seal had Teflon on both lips and the drive side seal only had a Teflon lip on the crank case side. The drive side of the seal exposed to the gear box oil was a plain lip.

I suspect the coating was to cope with the dirt and debris that gets blown through a road racing 2T crankcase. Whenever I took the cylinder off after a race there was a surprising amount of debris sitting at the bottom of the transfers.

[TZ350]

So how does this look as a two cone drive? Attached is a sketch of the components.

This is very interesting. I have been following it on the Foundry thread.

[lodgernz]

If one of the two lips has a spring, then this one is closer to the crank center.

Thanks Haufen, but both sides have springs.


.
My experience with Yamaha RD and TZ crankshaft seals that had (I think it was Teflon) coated lips, was that the coated lip faced into the crank case.
The Yamaha seals had springs on both lips. The mag side seal had Teflon on both lips and the drive side seal only had a Teflon lip on the crank case side. The drive side of the seal exposed to the gear box oil was a plain lip.
I suspect the coating was to cope with the dirt and debris that gets blown through a road racing 2T crankcase. Whenever I took the cylinder off after a race there was a surprising amount of debris sitting at the bottom of the transfers.

Thanks TZ. What I suspected.
My post was a bit wrong. I think the whole seal is Viton, and the coated lip is probably PTFE.
Interesting that the mag side seal on the Honda has just plain lips. Maybe it's not OEM.

[TZ350]

I think the whole seal is Viton, and the coated lip is probably PTFE.
Interesting that the mag side seal on the Honda has just plain lips. Maybe it's not OEM.

I did not know Honda also had seals with coated lips. I thought it was just a Yamaha thing as my Kawasaki and Suzuki's did not have them.

One of the issues I found with Yamaha coated seals was that they would curl up in the presence of Acetone. So when I ran my 50/50 mixtures of Acetone and Methanol I had to run Suzuki crank seals.

It would probably be a good idea to soak the seals overnight in a jar of whatever fuel mix you are going to use, just to check the seals compatibility.

[lodgernz]

I did not know Honda also had seals with coated lips. I thought it was just a Yamaha thing as my Kawasaki and Suzuki's did not have them.

One of the issues I found with Yamaha coated seals was that they would curl up in the presence of Acetone. So when I ran my 50/50 mixtures of Acetone and Methanol I had to run Suzuki crank seals.

It would probably be a good idea to soak the seals overnight in a jar of whatever fuel mix you are going to use, just to check the seals compatibility.

Should be OK. Being a good law-abiding bucket racer, I only use 98 pump gas. Don't think there's any acetone therein.

[TZ350]

Should be OK. Being a good law-abiding bucket racer, I only use 98 pump gas. Don't think there's any acetone therein.

Team ESE use fresh Av gas in their 2T Buckets because it is reliably consistent and so I have no real experience with 98. But I would be very suspicious about what sort of concoction is in it to achieve that 98 rating because it smells very nasty. I would definitely soak test the coated seals myself. Test is always best.

[speedpro]

Pretty sure there is a good % of toluol/toluene. A very good solvent.

[speedpro]

35%. that's why you can smell paint thinners when you first fire it up in the morning. It's only REALLY toxic so should be avoided if possible.

[F5 Dave]

Top tip: run some oil in there too. It helps lubricate the piston and the various crank bearings.

Don't mention it. :msn-wink: