ESE's works engine tuner

[Dutch Fisher]

Looks like this page has become corrupted.
There appears to be a body_id injected into the html code above the div class,
Not sure me saving this will correct it or its a server side muck up.


Edit, nope did nothing, still corrupted, looks like the post above this didn't save correctly.
PM sent to mods 01:25 server time

[Mental Trousers]

Can you guys stop breaking this. I actually had to think about how to fix this one.

[Dutch Fisher]

Can you guys stop breaking this. I actually had to think about how to fix this one.

It wasn't that hard for a man of your talents ;)



Frits, stop putting dodgy html code into the world ! :wacko:

[jacobson_se]

What would be a normal cht temp range on a TZ125 running ELF LMS unleaded?
Hard too find any guidelines for cht.
Wobbly do you measure cht on the KZ?

/Christer

[Frits Overmars]

Frits, stop putting dodgy html code into the world ! :wacko:I assume you're joking Dutch, but your smiley suggests otherwise.
I posted four lines of text and two JPG-pics; that's all. Nothing I haven't done a thousand times before.

[oktrg500]

Hi,
In this Racers magazine (No 25) about RGV250 (includes XR95-XR98) there is also some technical information. However, it's in japanese, but to me the pictures looks nice anyway.. I have attached some. Maybe possible to use a "text in picture translation app". I tried that but was not so successful at the time.

This free online tool says it can extract text from images. It also it can do Japanese. A highest possible image resolution is recommended.

https://www.onlineocr.net/

[Dutch Fisher]

I assume you're joking Dutch, but your smiley suggests otherwise.
I posted four lines of text and two JPG-pics; that's all. Nothing I haven't done a thousand times before.


yes fella i'm joking :2thumbsup

the page builder just had a fit over your site link coding, nothing you did, that's computers for ya

html code whatsup lesson over, back to 2 stroke engine thingy things :banana:

[husaberg]

I assume you're joking Dutch, but your smiley suggests otherwise.
I posted four lines of text and two JPG-pics; that's all. Nothing I haven't done a thousand times before.
I think what happened Frits was some what you wrote as your text was migrated into the code for the pics.
Thats what it loked like from looking at your latest post info when it occured last night,I have done it myself, its no major for someone of MT's skills.

[lohring]

And here I thought this site was allergic to piston port designs. I decided to take it to the limit with a divided intake. It takes a custom piston with a full skirt and a longer rod so the piston clears the crank web. I'm also considering Frits' 4 transfer design. It would fit on a stock crankcase with minor modifications. I'll need to finish modeling both versions to see if I missed anything.

Lohring Miller

337764 337765

[peewee]

alot of nsr500 photos. on the main menu is more bikes http://www.geocities.jp/noda_keni/h/00nsr500/00nsr500.htm

[husaberg]

alot of nsr500 photos. on the main menu is more bikes http://www.geocities.jp/noda_keni/h/00nsr500/00nsr500.htm
All of those pics and many more are here
https://www.kiwibiker.co.nz/forums/album.php?albumid=4837
On that website is some interesting stuff about balance and other related stuff.
I have spent a fair bit of time putting a lot of it together, and will be posting a heap of stuff rel;ated to whats on there and the Honda threes and fours in a few days.


NSR500 BIG BANG
Frits or Wob can correct me if i am wrong but from what i think have figured out is that the Big Bang Honda was not actually firing all its cylinders within 68 degrees.
The HRC director had said in many applications it was all within 68 degrees but as it was a 112 degree V four i believe he was meaning 68 crank offset was used for all cylinders which by addition would mean it was firing opposed pairs of cylinders at 90 degrees intervals if you take into account the V angles.
180 -112 =68
which makes sense as it basically converts it to having two sets of 90 degree v twins side by side with offset crankpins with the rocking couple mitigated by firing crossed pairs. it is in essence a double up ducati l twin and firing at similar intervals only twice as often.
The screamer was a two up two down firing in pairs 180 degrees apart same a a tz750 or all the other twin crank gp 500 bikes of the era this was first used in about 1989 and was according to the riders a great deal easier to ride than the previous which was 4 even evenly spread ignitions which fired every 90 degrees.
To do this a balance shaft was added.


KR3
Some stuff i found this morning
Note the crank on the later model and the water cooled transfers plus the early "Roberts" carbs
337829337831337832337827337830337828
there are plenty more pics here. another intersting detail. The early KR3 shared crankcase on two cylinders much like a ROC/swiss Auto/pulse did.
https://www.kiwibiker.co.nz/forums/album.php?albumid=5025
One thing i also never realised was they built a KR4 with a swiss Auto engine.

The YZR500 album is worth a look as well
https://www.kiwibiker.co.nz/forums/album.php?albumid=4845

[peewee]

while looking at the nsr stuff i found out yamaha was making all kinds of twin cyl engines that i never knew existed. probly rare as hens teeth. some inline with forward and reverse cyl and what appears to be a 90* offset.

[husaberg]

while looking at the nsr stuff i found out yamaha was making all kinds of twin cyl engines that i never knew existed. probly rare as hens teeth. some inline with forward and reverse cyl and what appears to be a 90* offset.
They followed the path of the TZ's first was the TZR250 IKT and 2MA then the reverse cylinder 3MA then the lastly the 3XV v twin
https://en.wikipedia.org/wiki/Yamaha_TZR250
the V twin had compatible parts with the TZ250A

[Haufen]

I think this is the post Frits tried to put up - MT (http://twostroketech.com/index.php?/topic/5661-26-cc-cylinder)




I'd like to take a look, but it seems that you have to be invited by a registered member in order to create an account. Could someone please invite me? Thanks.

[katinas]

Husa thanks, very interesting KR stuff and article about engine evolution, reading with one breath.
Cylinder B outlet looks more upward angle than usual and transfers inner wall cooling like Jan done on Aprilia .

European MX 65 final with rounded piston and sharp edge at C, mached head: after first race start, before first corner was in front, but close throttle too early, lost some places and later fallen down , so finished in 21 place.
Second race half distance holds in 6 place, but again fallen down and ended in 29 place. Engine worked really fine.


Interesting, Suzuki on RGV 250 XR96/98 used Mikuni with Yoshimura type multiple jet nozzle and in 1995 on XR95 they tried EFI with 40mm body (not on the factory "Lucky ..., but on JAJA team's engine, maybe in All Japan Championship).

[Martin1981]

Slowly I have gained enough credibility with them to get more detailed work, but there are very big ego's involved of course as they are the current World Title holders ( so dont need me involved ).
But I keep making more power than they do , so I just keep on doing it to annoy them.

Wobbly, i know EXACTLY what you are talking about......

several years ago i worked (lets say i tried to work) at a famous sports car manufacturer in germany for a half year.

but doing the work was not easy....the biggest part was not the work itself. most of the time you had to respect, appreciate and worship the employees and there egos for beeing part of such a famous glorious Company... you had to be very careful with jokes and easy conversation as they might take it serious and beeing angry on you until you apologize a 1000 times....stupid idiots!

so i know what is going on at tm....when you came in the first day they saw an unknown (by them) man in a wheelchair and thought "what can he do?"

and now of course they are angry or offended because you proved them wrong by beeing better than them.....as i said, stupid idiots!

maybe they could be much better than they are now. and maybe the gap between their knowledge and yours was not so big if they concentrated more on their development work instead of being busy polishing their offended egos and thinking about being world title holders.

so Wobbly, i recommend you to not waste that much time with them. do your job and leave. time is to precious to spend it with idiots.

but it is not easy to change things by trying to explain idiots that they are idiots.....been there done that (as Frits would say). it does not work. if an idiot understood that he is an idiot, it wouldn`t be an idiot! and, to make things worse, in the end they call you an idiot because you are not able to explain them...they hardly refuse of thinking about it beeing possible that it is not a question of explaining it but a question of understanding.

this reminds my of the story Frits once told.....after Jan Thiel left Aprilia his followers (i didnt want to use successors, because they didnt have success) "corrected" jans "mistakes" by making the crankcase smaller....once again, stupid idiots!

[Dutch Fisher]

Hi,
In this Racers magazine (No 25) about RGV250 (includes XR95-XR98) there is also some technical information. However, it's in japanese, but to me the pictures looks nice anyway.. I have attached some. Maybe possible to use a "text in picture translation app". I tried that but was not so successful at the time.

Looks like those pics got deleted in the melt down the other day.


Here's a scan i got off the german 2-takt website, i've translated the jap to english.

[Norman]

Nice!
Yes, it seems they went away. I will try and scan tomorrow, and thanks for the tip oktrg500.



Looks like those pics got deleted in the melt down the other day.


Here's a scan i got off the german 2-takt website, i've translated the jap to english.

[wobbly]

Thanks for the words of advise Martin.
As I understand it the problem was created by Jos V, who convinced TM he knew more than they when Max was trying to win a World title in KZ karts
He finally weaseled his way into Franco's dyno room and wasted his time for a month.
Max won using a factory Franco TM engine , but Jos then started selling tuned engines with all the mods he had seen.
Franco was not a happy man about this , so naturally me trying to get in the dyno door was made even harder.
But I became the first outside contractor they have ever used , to do the new pipe design , so with the great result that produced , and the cylinder CAD model I changed to a small
Exhaust duct nozzle with Aux port ears down the side into the spigot ( like Aprilia ) that also made big gains , things are not so much a one way street as it was.

[katinas]

RGV 500 pipes

https://www.ebay.co.uk/itm/Suzuki-RGV500-titanium-exhaust-pipes-similar-YZR500-NSR500-RGB500-set-of-4/253752633313?hash=item3b14d5e7e1:g:Yg0AAOSwIzBaycA Q

https://www.ebay.co.uk/itm/YZR500-500GP-SET-OF-V4-ENGINE-CASES-WITH-MAG-SIDE-COVER-not-rd500-project/132718788408?hash=item1ee6a7ff38:g:SXoAAOSw27FbPIW 6

[husaberg]

RGV 500 pipes

https://www.ebay.co.uk/itm/Suzuki-RGV500-titanium-exhaust-pipes-similar-YZR500-NSR500-RGB500-set-of-4/253752633313?hash=item3b14d5e7e1:g:Yg0AAOSwIzBaycA Q

https://www.ebay.co.uk/itm/YZR500-500GP-SET-OF-V4-ENGINE-CASES-WITH-MAG-SIDE-COVER-not-rd500-project/132718788408?hash=item1ee6a7ff38:g:SXoAAOSw27FbPIW 6

Cheers i flogged a few pics as well as the crank one i didn't already have.
Note is this the tungsten inserts edge welded in.
337880337881
The colour i guess is the copper coating?

Note the Crank is also 90 Degree's plus the seller saus it has 3VX rods so the sizes are the same or similar to the late TZR V twin.
337882

Here is a 180 Cagiva for comparison
plus some case pics
337883
337884 Cagvia Case
337885Yamaha YZR500 case

[Niels Abildgaard]

Cheers i flogged a few pics as well as the crank one i didn't already have.
Note is this the tungsten inserts edge welded in.
337880337881
The colour i guess is the copper coating?



It is most likely a 10% cupper-90 % wolfram alloy.
It is easy to machine and almost as heavy as pure wolfram.
It is used by the spark erosion people

[Dutch Fisher]

The colour i guess is the copper coating?


It is most likely a 10% cupper-90 % wolfram alloy.
It is easy to machine and almost as heavy as pure wolfram.
It is used by the spark erosion people


You sure that's not the copper plating used on cranks to to mask off areas where metal treaters don't want the nitriding process to act on?

[Norman]

Pictures attached, but it seems I am not capable of doing the translation.



Looks like those pics got deleted in the melt down the other day.


Here's a scan i got off the german 2-takt website, i've translated the jap to english.

[Norman]

Interesting with the heat isolation material there..If the engine is tuned at the dyno lab with a "low flow" air fan and then used on the track with the high air flows that one would expect to hit, especially the header, will no the exhaust gas have another temperature and the tuned length become out of phase compared to the dyno calibration? As I understand, as the exhaust port opens, the flow is very turbulent and the heat transfer to the walls in the exhaust port and the header/exhaust is high. Also thinking about Mr. Jan Thiels statement that the internal cleaned exhaust decreased performance a bit until a new carbon layer was created.




RGV 500 pipes

https://www.ebay.co.uk/itm/Suzuki-RGV500-titanium-exhaust-pipes-similar-YZR500-NSR500-RGB500-set-of-4/253752633313?hash=item3b14d5e7e1:g:Yg0AAOSwIzBaycA Q

https://www.ebay.co.uk/itm/YZR500-500GP-SET-OF-V4-ENGINE-CASES-WITH-MAG-SIDE-COVER-not-rd500-project/132718788408?hash=item1ee6a7ff38:g:SXoAAOSw27FbPIW 6

[flyincat]

Wobbly - I'm interested in learning more about the EGT vs jetting correction you preach, over and over, regarding dyno testing. You've stated numerous times about re-jetting after a change to get the EGT back to where it was before a modification. What I can't seem to find is much reference to the air fuel ratio (AFR). Could you say a few words about the affect on AFR when making these jetting changes to maintain a target EGT? Is re-jetting bringing the AFR back to where it was, along with the EGT? I hope the answer is YES because then I understand. But, coming from EFI and lambda sensors, I have a nagging thought that a jetting change = AFR change. In that case, the balancing act between AFR, ignition timing, detonation, EGT, etc. would need to be revisited as a whole, no? You don't seem to mention revisiting ignition timing and affects on detonation in your 're-jetting for EGT' warnings, so thought I would ask.

[wobbly]

Yes Dutch - the copper coating is used exactly for that process in heat treat.

Re the egt preaching lesson.
EGT in the header is a metric of the resultant wave speed in the pipe , due to the average gas temp along its length, plus the radiation rate thru the wall area.
One of the most important variables in a racing two strokes performance is the interaction of the wave speed with the pipe length.
I have done enough testing of the TM - KZ to know that best power temp for that pipe is 640*C , and from that result and knowing the RAD on that day I then have a graph to predict
the jetting for any weather at any track.
All you are doing by insisting on a baseline egt number is correlating the jetting to an optimum BSFC.
Less air needs less fuel = less Hp on the day, but the best power egt remains constant.
Anything that changes the egt ( weather, trapping efficiency due to porting etc ) will change how the pipe reacts - more so than the change itself.
So in answer to the question, as there is a direct correlation between egt and A/F ratio you would need to do the same process as I have done.
Find the best power A/F number and shoot for that every time.
BUT , every test MUST have the same pipe and water temp ,at the beginning and end of each pull , or the results are erroneously affected by the differing temp ,NOT the change you have made.
I could go on for another 5 pages about this , but you all will be bored by now anyway.

[41juergen]

Hey Wob, never boring! It's ike the desert when coming back from lunchtime into the office...:niceone:

[teriks]

I could go on for another 5 pages about this , but you all will be bored by now anyway.
No way I'm bored by your in depth information/discussion of two strokes, 5 pages wouldn't be even close! 500 pages on jetting alone then maybe...

[husaberg]

Yes Dutch - the copper coating is used exactly for that process in heat treat.
.
What did you think of my Theory that the Honda NSR500 BIG bang was just a 90 degree doubled up v twin Wob?
In that 68 Degrees Honda spoke of was just the offset to make it a 90 degree twin on account of the 112 degree V.


Also that last pic i posted did you notice the hollow pin on the left crank-wheel next to the welding locked in with peen, i first thought it was a pressed in mainshaft but its not in the middle. why would they use a hollow weight pin that far inboard, a mistake or modification?
337898

the other pic shows it as well from the other side.
337899

[190mech]

Perhaps its a locking dowel to keep the crank from twisting like the ones you posted at #2369 in the "oddball engines"
thread?

[husaberg]

Perhaps its a locking dowel to keep the crank from twisting like the ones you posted at #2369 in the "oddball engines"
thread?
it Just seems way to big ,but it is parallel with it though?

[katinas]

Add some drawings from "Racers" that can be helpful about YZR, NSR "Crank-angle-firing-forces".

[flyincat]

All you are doing by insisting on a baseline egt number is correlating the jetting to an optimum BSFC.
Less air needs less fuel = less Hp on the day, but the best power egt remains constant.
Anything that changes the egt ( weather, trapping efficiency due to porting etc ) will change how the pipe reacts - more so than the change itself.


Thanks for sharing. This is good stuff! Feel free to go on another 5 pages because we are TWO THOUSAND in so far. :cool:

Are the EGT changes due to weather and engine modifications (trapping efficiency) handled the same?

It's clear the jetting adjustments for the weather at the track, dyno, etc to maintain a tune. However it does bring up a good point about dyno corrections for 2T. The regular atmospheric dyno corrections probably don't account very well for 2T performance differences, assuming you didn't make any jetting corrections. The change in EGT probably causes a much bigger performance change than just the straight up atmospheric correction. I think that's what you are saying if I restated correct.

Also interesting is the radiation prediction for the day. I assume rain or mud on a pipe would add another variable into the prediction equation for the day.

Now onto the changes due to, I'll call it, engine modifications (porting, compression, squish etc.). Let's say you changed compression and/or squish. If you re-jet back to your baseline EGT, couldn't your AFR actually end up different? Changing the squish, for example, effectively changes the burn rate and combustion timing. It seems any timing change, burn rate or ignition, could result in a totally different combustion characteristic to get back to target EGT. At this point would you go back to AFR and ignition timing sweeps to find best power, and record your new target EGT?

Then there is the exhaust... Are there any modifications to the exhaust that you simply re-jet for target EGT and measure power difference instead of doing AFR and ignition timing sweeps to find new best power EGT?

[Frits Overmars]

Pictures attached, but it seems I am not capable of doing the translation.Never mind Norman, as long as the pictures themselves are in English :p.
I encountered this engine in the Molenaar GP-team where Hans Spaan tried to bring it on par with the 250 cc works Hondas on which he had been working previously. The Suzuki suffered from a lack of power and an overdose of complexity. Each cylinder had an exhaust power valve with no less than three blades, called SAEC, and an ATAC-type resonance volume, called AETC, which brought a lot of unwelcome heat in the cylinders.
Spaan planned to produce his own cylinders (which would have had all the characteristics of Honda cylinders) but when Suzuki got wind of it, they insisted that the factory would take care of that, if Hans would only provide the drawings. Nothing ever happened, but in any case Suzuki did not lose face quite as much as Yamaha did, when Harald Bartol made them pay him for putting shameless Honda-copies on the Yamaha TZ125 (and on the 125 cc Derbis. And on the 125 cc and 250 cc KTMs).
The best thing of the Suzuki works engines were their pistons, consisting of a light-alloy base material with embedded ceramic fibers. Spaan claimed they lasted ten times as long as Honda pistons.
337907

[Dutch Fisher]

Pictures attached, but it seems I am not capable of doing the translation.


Translated, but any others you want translating will have to be 1920x1080 x 600dpi, easier for the OCR

[Dutch Fisher]

Add some drawings from "Racers" that can be helpful about YZR, NSR "Crank-angle-firing-forces".

https://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=337903&d=1533200780


Looks like the big bang was designed to have zero piston acceleration on the bottom cylinder while the top cylinder was on max deceleration (TDC), poss. 50% primary on the crank wheel married to 50% on the balancer ¯\_(ツ)_/¯

[Dutch Fisher]

Spaan planned to produce his own cylinders (which would have had all the characteristics of Honda cylinders) but when Suzuki got wind of it, they insisted that the factory would take care of that, if Hans would only provide the drawings. Nothing ever happened,


Likely fell to unwritten Japanese rule of not copying each others designs.




.....but in any case Suzuki did not lose face quite as much as Yamaha did, when Harald Bartol made them pay him for putting shameless Honda-copies on the Yamaha TZ125 (and on the 125 cc Derbis. And on the 125 cc and 250 cc KTMs).


Not forgetting the money Bartol received from the eyeties for the Gilera GFR250, with that perticular unit sporting some very Yamaha looking clyinders.

[Frits Overmars]

https://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=337903&d=1533200780
Looks like the big bang was designed to have zero piston acceleration on the bottom cylinder while the top cylinder was on max deceleration (TDC)Yep.......

[Norman]

Yes, I am glad the pictures are not in Japanese, but I would not be surpised if Mr. Dutch Fisher could have fixed that too!:rolleyes:


Never mind Norman, as long as the pictures themselves are in English :p.
I encountered this engine in the Molenaar GP-team where Hans Spaan tried to bring it on par with the 250 cc works Hondas on which he had been working previously. The Suzuki suffered from a lack of power and an overdose of complexity. Each cylinder had an exhaust power valve with no less than three blades, called SAEC, and an ATAC-type resonance volume, called AETC, which brought a lot of unwelcome heat in the cylinders.
Spaan planned to produce his own cylinders (which would have had all the characteristics of Honda cylinders) but when Suzuki got wind of it, they insisted that the factory would take care of that, if Hans would only provide the drawings. Nothing ever happened, but in any case Suzuki did not lose face quite as much as Yamaha did, when Harald Bartol made them pay him for putting shameless Honda-copies on the Yamaha TZ125 (and on the 125 cc Derbis. And on the 125 cc and 250 cc KTMs).
The best thing of the Suzuki works engines were their pistons, consisting of a light-alloy base material with embedded ceramic fibers. Spaan claimed they lasted ten times as long as Honda pistons.
337907

[husaberg]

https://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=337903&d=1533200780


Looks like the big bang was designed to have zero piston acceleration on the bottom cylinder while the top cylinder was on max deceleration (TDC), poss. 50% primary on the crank wheel married to 50% on the balancer ¯\_(ツ)_/¯
I agree with the first bit but not the second.
MY take is the two lots of 50% are the balance factor on each crankshaft, ie half from the opposing piston and half from the counterweight .to achieve 100% primary balance
the balance shaft is for secondary forces, it was added for the two up crank 180 degree crank used the last two years before the big bang. Its main function is the jack-shaft to change the direction of the engine to lessen gyro.
If my theory is correct I dont believe the big bang even really needed it.


Ducati twins have V-angle 90 degrees. This uniquely makes it possible to balance a 90-degree twin with counterweights of 100 percent of one piston’s shaking force. Here’s how it works. At the front cylinder’s TDC and BDC, the heavy crank counterweights cancel the front piston’s shaking force. But at 90 degrees and 270 degrees, those same heavy counterweights now cancel the TDC and BDC shaking force of the rear piston. In other words, both primary piston shaking forces are 100 percent balanced,
<img src="https://hips.hearstapps.com/amv-prod-cad-assets.s3.amazonaws.com/images/media/51/two-timer-576-px-photo-369911-s-original.jpg" height="230px"/><img src="https://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=337903&d=1533200780" height="230px"/>

[jamathi]

Never mind Norman, as long as the pictures themselves are in English :p.
I encountered this engine in the Molenaar GP-team where Hans Spaan tried to bring it on par with the 250 cc works Hondas on which he had been working previously. The Suzuki suffered from a lack of power and an overdose of complexity. Each cylinder had an exhaust power valve with no less than three blades, called SAEC, and an ATAC-type resonance volume, called AETC, which brought a lot of unwelcome heat in the cylinders.
Spaan planned to produce his own cylinders (which would have had all the characteristics of Honda cylinders) but when Suzuki got wind of it, they insisted that the factory would take care of that, if Hans would only provide the drawings. Nothing ever happened, but in any case Suzuki did not lose face quite as much as Yamaha did, when Harald Bartol made them pay him for putting shameless Honda-copies on the Yamaha TZ125 (and on the 125 cc Derbis. And on the 125 cc and 250 cc KTMs).
The best thing of the Suzuki works engines were their pistons, consisting of a light-alloy base material with embedded ceramic fibers. Spaan claimed they lasted ten times as long as Honda pistons.
337907

Bartol also STOLE the fairing models from DERBI, and used them on the KTM.
They were made for DERBI by Porsche.
And of course paid for by DERBI.

Later, while testing the RSA engine in 1996 it was discovered that this fairing had a very negative effect
on steering, especially at high speeds!!!
Only good in a straight line...…The bike only wanted to go straight....
Shame on Porsche!!!

And Yamaha also copied the Honda cylinders on the 500/4's, helped by Bartol.
As did Yamaha-France for their 250's.
Yamaha even published an SAE paper about this....
Really SHAMEFUL!

Maybe Honda, just like Aprilia, liked to SELL a lot of pistons.
At Aprilia this was bringing in lots of cash----
80% gains on the price, or more!
Only few people knew this.....

[Dutch Fisher]

... poss. 50% primary on the crank wheel married to 50% on the balancer



MY take is the two lots of 50% are the balance factor on each crankshaft,

We are saying the same thing..


At the risk of the blind leading the blind (kinematics are my weakest topic) here's a theory.


Using the formula I stated earlier (2xAv)-180) the 112* comes out spot on at 44* pin offset.
That means primary balance is achieved right there, as noted by the zero piston accleration on the bottom cylinder and max decel on the top cylinder (TDC)

The fly in your soup is the secondary forces are having a party in a wasps nest and buzzing away merrily.
I've modded the pic and added the sum of inertia force lines of the secondary in yellow.
Now it seems Honda has approached this problem (likely 2 mins on the back of a cigarette packet for them) by reduced the crank balance factor to 50% and added that other 50% to the balancer so maintaining primary balance. This has allowed them to use a good % of the rotating interia of the balancer counter weight (thats counter-rotating) to offset a fair degree of that untamed secondary inertia force.
The counter force angles are not absolutely in-line while at their respective peaks, but it looks like the level of vibratory forces is reduced to the point that its ok to solidly mount the crankcase into the frame.

[husaberg]

Loads of RGV500 pics
including inside the crankcases
https://www.kiwibiker.co.nz/forums/album.php?albumid=4848
338033338034338035338036338037338038

[jamathi]

Likely fell to unwritten Japanese rule of not copying each others designs.




Not forgetting the money Bartol received from the eyeties for the Gilera GFR250, with that perticular unit sporting some very Yamaha looking clyinders.

It is well known that Gilera got Kocinsky's bike from Yamaha after John won the championship on it.
Gilera did not excactly improve it, stupid fools....
And even the great Bartol failed miserably....
They spent millions for nothing!

[katinas]

All is very interesting, thanks.

Looks like RGV 500 piston skirt cut at C is big like on street RGV 250 and at the same level like main side cuts. Street RGV 250 piston skirt looks very fragile, but is it made for better flow acceleration through C port, when piston at TDC , or for less obstructed way in/out crankcase when piston at BDC.

Add RGV 500 XR78 1989 cylinder drawing, and probably this was first decade when was discovered that A higher than B work in good way for wider power range, but really I don't know. Ex duct with small step and then two sections before pipe.

Looks like on Honda RSW 250 2009 cylinder duct and spigot dimension gradually changed before pipe without step.

NSR 500 crank-sprocket chain.

[TZ350]

338045
Suzuki on RGV 250 XR96/98 used Mikuni with Yoshimura type multiple jet nozzle and in 1995 on XR95 they tried EFI with 40mm body (not on the factory "Lucky ..., but on JAJA team's engine, maybe in All Japan Championship).

Chambers has a 24mm version of one of those carbs on his F5 Suzuki RG50 Bucket, seems to work Ok.

338043 338044

[katinas]

Chambers has a 24mm version of one of those carbs on his F5 Suzuki RG50 Bucket, seems to work Ok.

338043 338044

Interesting how better atomization influence two stroke piston cooling at high revs.
Yoshimura developed this for four stroke GSX-R SBK from 1988 and was launched in 1992.

[Norman]

The steps and contracting exhaust ducts; could it be that they help such that the exhaust gas does not heat up the duct walls as much. The flow get's separated from the walls after the step? The air-fuel slug going out in the exhaust port will be less heated up? (As the exhaust port opens there is a lot of tubulence and pressure which enhances forced convective heat transfer a lot)



All is very interesting, thanks.

Looks like RGV 500 piston skirt cut at C is big like on street RGV 250 and at the same level like main side cuts. Street RGV 250 piston skirt looks very fragile, but is it made for better flow acceleration through C port, when piston at TDC , or for less obstructed way in/out crankcase when piston at BDC.

Add RGV 500 XR78 1989 cylinder drawing, and probably this was first decade when was discovered that A higher than B work in good way for wider power range, but really I don't know. Ex duct with small step and then two sections before pipe.

Looks like on Honda RSW 250 2009 cylinder duct and spigot dimension gradually changed before pipe without step.

NSR 500 crank-sprocket chain.

[TZ350]

Interesting how better atomization influence two stroke piston cooling at high revs.

Yes, good point. maybe not so much piston cooling, might be a problem..... :scratch:

[jonny quest]

I've heard of a lot of Honda cylinders being copied by other manufacturers. Why wasn't the RSA copied if it far superior?

Jan or Frits, have either of you helped any motocross teams with their engine development?

[peewee]

Why wasn't the RSA copied if it far superior?


because nobody could get their hands on one ? thats my guess anyways

[jamathi]

because nobody could get their hands on one ? thats my guess anyways

A Danish kart engine manufacturer bought an RSA cylinder at Aprilia and copied it.
A French kart engine manufacturer bought a complete RSA after the last 125cc race.
All 250cc superkart engines are now Aprilia copies.

[jamathi]

[QUOTE=jonny quest;1131105619]I've heard of a lot of Honda cylinders being copied by other manufacturers. Why wasn't the RSA copied if it far superior?

Jan or Frits, have either of you helped any motocross teams with their engine development?[/QUOTE

No, I never did!

[husaberg]

A Danish kart engine manufacturer bought an RSA cylinder at Aprilia and copied it.
A French kart engine manufacturer bought a complete RSA after the last 125cc race.
All 259cc superkart engines are now Aprilia copies.

The KTM MX cylinders show a definite Aprilia influence.
As do the DEA cylinder moulds i have, they well buggered up your septum's though.
The rest is pretty close to the RSV/RSW era cylinders though.

Piecing together what i have found it seems pretty much anything two stroke right from the elisnore that came out of honda up until the late 90's had one designers fingerprints on it.

[katinas]

Remember very serious efforts from Holland with Honda RS 125 engines and Aprilia type cylinders, with very good results, but can't find quickly. They adopted biggest Honda CR 125 four petals reed cage version for this project

[husaberg]

We are saying the same thing..


At the risk of the blind leading the blind (kinematics are my weakest topic) here's a theory.


Using the formula I stated earlier (2xAv)-180) the 112* comes out spot on at 44* pin offset.
That means primary balance is achieved right there, as noted by the zero piston accleration on the bottom cylinder and max decel on the top cylinder (TDC)

The fly in your soup is the secondary forces are having a party in a wasps nest and buzzing away merrily.
I've modded the pic and added the sum of inertia force lines of the secondary in yellow.
Now it seems Honda has approached this problem (likely 2 mins on the back of a cigarette packet for them) by reduced the crank balance factor to 50% and added that other 50% to the balancer so maintaining primary balance. This has allowed them to use a good % of the rotating interia of the balancer counter weight (thats counter-rotating) to offset a fair degree of that untamed secondary inertia force.
The counter force angles are not absolutely in-line while at their respective peaks, but it looks like the level of vibratory forces is reduced to the point that its ok to solidly mount the crankcase into the frame.

I found this bear in mind its been translated from Japanese to english

Supplement 2 Description of Riding Sports 2012-9
　"Although this engine is a two-cylinder simultaneous explosion engine, since the two banks explode simultaneously at 68 ° -292 ° intervals ~ V bank angle of NSR 500 is 112 °, theoretically the primary vibration is zero For this reason, the balancer shaft became unnecessary in the 1992 model, and due to the three-axis configuration, the rigidity and precision of the engine alone were upgraded "(page 58)
As with supplementation 1- (2), it seems that Mr. Writer misunderstood that the 1992 type NSR 500 misunderstood that the primary inertial force is perfectly balanced without the balancer shaft. "Three-axis configuration" ... ... "Exploring the NSR 500 Hyper 2 st engine" (Tsukasa Tsukasa, 1995 Grand Prix publication) Other publications have written about the balancer shaft (that is, it becomes a 4-axis configuration) It seems to be a product of imagination due to wrong recognition of Mr. Lighter's primary vibration.


Remember very serious efforts from Holland with Honda RS 125 engines and Aprilia type cylinders, with very good results, but can't find quickly. They adopted biggest Honda CR 125 two petals reed cage version for this project

Frits knew the guy they dont do them anymore very nice looking cylinders..
there are some pics in my aprilia and my crankcase album.
I think it was the same guy that was doing the doubled up disc valve crankcases.

Last time i looked at his site it had mainly 4T stuff plus the odd 2 stroke mini bits and bobs.
It was three initials JHE? or somthing its one my other computer.

[katinas]

This project

[jamathi]

I found this bear in mind its been translated from Japanese to english



Frits knew the guy they dont do them anymore very nice looking cylinders..
there are some pics in my aprilia and my crankcase albulm.
I think it was the same guy that was doing the doubled up disc valve crankcases.

Last time i looked at his site it had mainly 4T stuff plus the odd 2 stroke mini bits and bobs.
It was three initials JHE? or somthing its one my other computer.

I think you mean my friend Thijs Hessels.

All RSA cylinders were tested on a RSW engine.
Because to work well on an RSA you had to cut off the under/rearside of the cylinder....
As it stood in the way of the RSA's inlet flow.
After that it gave less power on the RSW and 250.
And most cylinders were destined for 250...

[husaberg]

I think you mean my friend Thijs Hessels.

All RSA cylinders were tested on a RSW engine.
Because to work well on an RSA you had to cut off the under/rearside of the cylinder....
As it stood in the way of the RSA's inlet flow.
After that it gave less power on the RSW and 250.
And most cylinders were destined for 250...

Thats him
Was it him who was making the CNC double disc crankcases?
338071

[jamathi]

Thats him
Was it him who was making the CNC double disc crankcases?
338071

Yes, but not 1 engine was ever finished....

[husaberg]

Yes, but not 1 engine was ever finished....

So what happened to all the cases?

[Dutch Fisher]

Well I never...


What I first thought was water cooling for the Aoyama RSW crankcase, turns out to be air cooling.
Having seen an air scoop under the engine in pics of the bike sans bodywork, I turned the old brainbox over with my fav cranking handle and concluded that it was an entry for a gearbox oil cooling system. Wrongamondo!!

I guess you could call it air cooling, more like an active insulator for the CC from the heat of the GB

Honda state on their website that the 2009 bike was 'old', I'm not so sure, i can't as yet find this air cooling system (the big black air scoop) on the 2006 bike. Has anyone?

http://i456.photobucket.com/albums/qq281/Saving4parts/250%20GP%20Bikes/Honda2503.jpg

[dutchpower]

[QUOTE=husaberg;1131105671]The KTM MX cylinders show a definite Aprilia influence.


There is totally nothing that looks like RSW/RSA on KTM 125 sx

[katinas]

Looks nice and compact

https://grassrootsmotorsports.com/articles/two-strokes-genius/

[husaberg]

There is totally nothing that looks like RSW/RSA on KTM 125 sx
The little uns 50 and 65.

[diesel pig]

Piecing together what i have found it seems pretty much anything two stroke right from the elisnore that came out of honda up until the late 90's had one designers fingerprints on it.

Do you mean Shin'ichi Miyakoshi? In Kevin Cameron's book "Classic Motorcycle Race Engines" he writes when Honda realised in 1981 they were never going to win with the four stroke NR500 (wags said the NR stood for never ready!) in GP500 racing and would need a two stroke. They needed someone with two stroke racing experience, Miyakoshi was the only one in the company who had it having headed the design of the MX Elisnore's in the 70's.

[husaberg]

Do you mean Shin'ichi Miyakoshi? In Kevin Cameron's book "Classic Motorcycle Race Engines" he writes when Honda realised in 1981 they were never going to win with the four stroke NR500 (wags said the NR stood for never ready!) in GP500 racing and would need a two stroke. They needed someone with two stroke racing experience, Miyakoshi was the only one in the company who had it having headed the design of the MX Elisnore's in the 70's.

Yip that's right according to legend he had brought a few overseas mx bikes and looked at them to see how they were built.
He then made the CR Elsinore and was testing it on the sly, supposedly without Hondas full knowledge and consent.
Soichiro honda was not impressed when he found out, but when it was shown to be rather good and a large potential seller he relented and let it proceed.
Miyakoshi's finger prints were on pretty much all Honda two strokes up to and including the NSR500 big bang as well as a lot of Four stroke in the 60's GP era
Another story is the original goldwing was designed and built only to be a flat six and when Soichiro seen it he made them turn it into a four.

[jato]

For a company that has always "believed" in 4 strokes i've always thought Honda make better two strokes than most of their competition - with the exception of the mvx 250...

[jamathi]

For a company that has always "believed" in 4 strokes i've always thought Honda make better two strokes than most of their competition - with the exception of the mvx 250...

Yes, they definitely did much better than Yamaha and Suzuki!

[Dutch Fisher]

Yes, they definitely did much better than Yamaha and Suzuki!


With the breath and depth of resources that Honda have, no surprises they'd be on top even if they did make the odd blunder in design or appilcation. So many resources infact, I'm in no doubt they designed the 250 twin crank in 1998 just for Katoh to take advantage of his small size. A japanese WC on a japanese bike, that s a big prize in the land of nippon.




Jan I'm curious, did any of the Japanese manufacturers ever approach you to work or do consultation on engine projects for them?

[jamathi]

With the breath and depth of resources that Honda have, no surprises they'd be on top even if they did make the odd blunder in design or appilcation. So many resources infact, I'm in no doubt they designed the 250 twin crank in 1998 just for Katoh to take advantage of his small size. A japanese WC on a japanese bike, that s a big prize in the land of nippon.

Honda also bought a 250cc ROTAX engine.




Jan I'm curious, did any of the Japanese manufacturers ever approach you to work or do consultation on engine projects for them?

I once talked with Yamaha-people.
Later I had an appointment with Suzuki-people, but then the 4strokes came.....

[Flettner]

ok, it would seem the Link ecu can 'read and hold' a crank case pressure value. Just not internally, but the ecu can drive some circuitry to read then hold an output from the MAP sensor. Using some transistors and a small capacitor, dumped and reloaded every cycle but only dumped when the main reading occurs then switched in untill the next cycle (reading).

[TZ350]

ok, it would seem the Link ecu can 'read and hold' a crank case pressure value. Just not internally, but the ecu can drive some circuitry to read then hold an output from the MAP sensor. Using some transistors and a small capacitor, dumped and reloaded every cycle but only dumped when the main reading occurs then switched in until the next cycle (reading).

I received my Speeduino fuel injection ECU kit today. Being a shield for an Arduino with open source code I should be able to write a sample and hold routine and incorporate it in the main control program. If not then I will follow Flettners lead and go the Link way.


338158

[katinas]

[QUOTE=Dutch Fisher;1131105717]Well I never...

Another from "Well I never knew that...!" box.
When Kawasaki decide to return to 250, they started with pararel twin ( KR-1 street version) 1987-88 and ended in 1993 with radical upside down V 90 with firing angle 90 . But between this two versions was third (add photo): Well I never... "normal" engine position, V 75 angle with 105 firing angle in 1989-1990. Best result 17 place in All Japan Championship race in 1990.

After first period with V90 and 90 angle firing (inline crank pins), Honda release NSR with V75 in 1992 and RS/NX5 in 1993. With offset crank pins, firing angle 60 (if pins offset 15 degrees, not sure precisely, in advance position from the first working pin) and they hold this on RS until the end. But on NSR, from 1997 or 1996 ( except Katoh's two crank, real big- bang with 0 angle firing) and later RSW, they stick to Kawasaki's 105 firing angle, with 20 ( oh sorry 30 thanks Dutch Fisher) degrees crank pins offset in retard position from the first working pin.

But late Honda RSW 250 crank photo from 'Racers', with inline crank pins, probably indicate that they tried 75 firing angle on Aoyama's bike, maybe upgrade throught the 2009 season. But designed drawings on Aoyama's bike fairing from ignition side, show 105 pic up angle, but this is only paint.....

[JanBros]

[QUOTE=Dutch Fisher;1131105717]Well I never...

Another from "Well I never knew that...!" box.

But between this two versions was third: Well I never... "normal" engine position, V 75 angle with 105 firing angle in 1989-1990. Best result 17 place in All Japan Championship race in 1990


you are right about that !

any more info ?
I'm curious though : as it probably is one of the most secret race-bikes ever - only 2 outings known : '91 Shah Alam and '92 Daytona - : if it was raced in Japan how come in 1990, surely their should be some mention of it somewhere ?

[katinas]

[QUOTE=katinas;1131106071]

you are right about that !

any more info ?
I'm curious though : as it probably is one of the most secret race-bikes ever - only 2 outings known : '91 Shah Alam and '92 Daytona - : if it was raced in Japan how come in 1990, surely their should be some mention of it somewhere ?

Yes, but this was upside down version V90 and very sad that they not return to V75 normal configuration ( say, with different, 54x54 mm) engine with new chassis after 1993. As I read, the chassis on late 93' with upside down engine was superb. V75- 50.6mm stroke, V90 upside down- 50.7mm.

Someone, even made 1/12 scale model of this 1989 bike with V75 engine, but foto only with the fairing.

[Dutch Fisher]

[QUOTE=Dutch Fisher;1131105717]Well I never...

Another from "Well I never knew that...!" box.
When Kawasaki decide to return to 250, they started with pararel twin ( KR-1 street version) 1987-88 and ended in 1993 with radical upside down V 90 with firing angle 90 . But between this two versions was third (add photo): Well I never... "normal" engine position, V 75 angle with 105 firing angle in 1989-1990. Best result 17 place in All Japan Championship race in 1990.

After first period with V90 and 90 angle firing (inline crank pins), Honda release NSR with V75 in 1992 and RS/NX5 in 1993. With offset crank pins, firing angle 60 (if pins offset 15 degrees in advance position from first working pin, not sure precisely) and they hold this on RS until the end. But on NSR, from 1997 or 1996 ( except Kato's two crank, real big- bang with 0 angle firing) and later RSW, they stick to Kawasaki's 105 firing angle, with 20 degrees crank pins offset in retard position from first working pin.

But late Honda RSW 250 crank photo from 'Racers', with inline crank pins, probably indicate that they tried 75 firing angle on Aoyama's bike, maybe upgrade throught the 2009 season.


As far as I can tell, all the V75 Honda are pin offset 30* firing angle 105*, its the natural setup for primary. That inline pin crank pic is a head scratcher, if anyone has the NSR250 Racers mag and can photo the pages at 3200 x 1800 (that sample page is at that reso and OCR'd perfectly) I'll happily translate the whole mag, just make sure that the pages are as flat as poss (sheet of glass with no reflections) we see what they say about Aoyama engine.

Katoh's appears to be a 120* twingle, again another natural angle for that design along with 90*, 60* and 180*


As for the Kawa 250 effort, a bit bizarre esp. keeping with the gen1 KIPS.

[katinas]

[QUOTE=Dutch Fisher;1131106092][QUOTE=katinas;1131106071]


pin offset 30* firing angle 105* .... Katoh's appears to be a 120* twingle, again another natural angle for that design along with 90*, 60* and 180*





Yes, I lost 10 degrees .....of course 30...thanks, but two cranks NSR drawing and technical info, indicate 110 cylinders angle and 0 firing difference

[Dutch Fisher]

[QUOTE=Dutch Fisher;1131106092][QUOTE=katinas;1131106071]


pin offset 30* firing angle 105*


Yes, I lost 10 degrees .....of course 30...thanks, but two cranks NSR drawing and technical info, indicate 110 cylinders angle and 0 firing difference

Another 'well i never' to the naked eyeball it appears 120* more balancing shenanigans from Honda

[katinas]

[QUOTE=katinas;1131106071]


That inline pin crank pic is a head scratcher, if any.

Yes, specification table indicate that from 2002 to 2009 on RSW just V75 and 105 firing used, only 40mm carb was used from 2006.
So Kawasaki starting, Honda ending (maybe with 75 firing, inline pin crank, like they started in 1984 with V90).

[guyhockley]

Not a 2 stroke question but... That looks like a Hurst Airheart master cylinder in the inset photo. Did the Enfiled run a rear disc, or was it a rear hydraulic drum brake, in '65?

Way, way off topic, sorry TZ, but I said I'd check this out... weeks ago.

Better late than never, hopefully. This is what I've got.

[katinas]

I once talked with Yamaha-people.
Later I had an appointment with Suzuki-people, but then the 4strokes came.....

Jan, maybe you have some ideas about this Yamaha 250 rotary engine. Its V60 and from ignition side looks like firing on both cylinders at the same time.

[JanBros]

[QUOTE=JanBros;1131106086]

Yes, but this was upside down version V90 and very sad that they not return to V75 normal configuration ( say, with different, 54x54 mm) engine with new chassis after 1993. As I read, the chassis on late 93' with upside down engine was superb. V75- 50.6mm stroke, V90 upside down- 50.7mm.

Someone, even made 1/12 scale model of this 1989 bike with V75 engine, but foto only with the fairing.

So basicly the 2 prototypes known to mortals (one with upsidedown forks, other one with right side up) are very different ? How come you know about the V75° if I may ask as you appear to be a non-mortal :msn-wink: any more info ?

[katinas]

[QUOTE=katinas;1131106087]

So basicly the 2 prototypes known to mortals (one with upsidedown forks, other one with right side up) are very different ? How come you know about the V75° if I may ask as you appear to be a non-mortal :msn-wink: any more info ?

Mortal, have some experience. All info from Racers magazine, I am really surprised too when found this. From all photos on internet about Kawasaki X-09, it easy indicate who is who.
With upsidedown forks and with right side up with casting legs- V90 upsidedown engine.
With right side up forks and brown anodized legs made from billet or two piece - V75 engine.
Fairing on V75 with big side ducts for air from radiator.

[katinas]

With the breath and depth of resources that Honda have, no surprises they'd be on top even if they did make the odd blunder in design or appilcation. So many resources infact, I'm in no doubt they designed the 250 twin crank in 1998 just for Katoh to take advantage of his small size. A japanese WC on a japanese bike, that s a big prize in the land of nippon.

Yes, and Katoh, as wild card, wins first 1998 season Suzuka race with new, first generation, two crank engine. And very interesting, with new lead free fuel regulation, they started with under square 52x58mm configuration, mainly to minimize detonation with smaller piston. But later, return to 54x54mm, because no gains and some power lose.

[Dutch Fisher]

Looks like the big bang was designed to have zero piston acceleration on the bottom cylinder while the top cylinder was on max deceleration (TDC)


Hold on a minute there cowboy, seems my engineer eyeball has tripped me up again.
A few light fandangos with the fingers on the special calculator and using Hondas fav 104mm rod C-to-C and 27mm crank radius (54 stroke)
we've got max piston velocity (zero accel) at 76.6* not 68, opps! luckily the top cylinder is on max deaccel. :sweatdrop

[crbbt]

Anyone happen to know the radius of the dome piston for a CR250 (05-07)

[husaberg]

Yes, and Katoh, as wild card, wins first 1998 season Suzuka race with new, first generation, two crank engine. And very interesting, with new lead free fuel regulation, they started with under square 52x58mm configuration, mainly to minimize detonation with smaller piston. But later, return to 54x54mm, because no gains and some power lose.

When you look at the Twin crank Honda layout its rather seems to be a tacit admission from Honda they cant match the Aprilia on HP
So they try the next best thing attempt to repackage the bike to make it narrower.
From Memory the Twin crank had the side mounted radiators as well. (Shades of NR500)
The radiators normally being the widest part of the frontal area.
On a side note The other possible reason for the twin crank which would cost HP would be to less the Gyro.
Honda had made up twin crank NSR500 prototypes in 1987 and i believe again in 1992.

Thanks, very interesting story.
I am very surprised when found this photo, that shows how Honda was keen about carbon comstar wheels, even after some Spencer's era problems. One of many changes that E. Lawson tried in 1989 was comstar "2nd version" front carbon wheel and AP brake discs. Carbon 3.75x16 =2.5kg, magnesium=2.6kg, but 17in version carbon= 2.83kg magnesium=2.81kg.
You showed a carbon wheel on Lawsons bike the other day.
I can confirm that not only were they used on the Freddie Spencer bikes a few years prior to that the wheels that Lawson used actually were left overs from Freddies bikes as Honda considered it to costly to make more.
338358
one os Freddie's bike also had CF reinforced forks. as did Lawsons
Freddie had one wheel blow to bits at south Africa one year from the early batch.
He had used Carbon discs in 82 and even A CF swingarm at various times on The NS500.
338357
Honda painted up the CF swingarm so it looked aluminium.
338360338359
Pretty sure the NR500 had Carbon wheels and Discs at one stage as well, it certainly had a CF frame in one version. (cf swingarm as well)
338361338362
A lot of people say Honda should have won GP bike classes as they used huge resources and money i dont really find that rings true when you look at the size of the crew Kenny Roberts had compared to HRC.

[katinas]

....On a side note The other possible reason for the twin crank which would cost HP would be to less the Gyro.....

With two crank configuration they equalize both cylinders inlet and exhaust, this help on power side.
Cost HP only on 52x58mm config. and with bad cooling from side radiators in 1998 (very young engineers team involved in this project with swingarm-crankcase attachment experiments ), but return to 54x54mm in 1999 on two crank engine with front side radiator and gain HP again. 2000-2001 they are very happy with the bike, but when Katoh won championship, goal was reached, all resource was redirected to last NSR 500 and 4-t.
So 250 team left to do something with RS/NX.

[husaberg]

Cost HP only on 52x58mm config. and with bad cooling from side radiators in 1998 (very young engineers team started this project), but return to 54x54mm in 1999 on two crank engine with front side radiator and gain HP again. 2000-2001 they are very happy with the bike, but when Katoh won championship, they reach the goal, and redirecting all resource to last NSR 500 and 4-t.
So 250 team left with RS/NX.

Yeah it might have had more HP, But thats only part of the equation of what makes HP, What i am saying is two cranks cost HP in friction compared to the same spec single crank.
Every thing else being equal ie cylinders, pipes, carb, intake layout, airbox etc. A single crank will give more HP just as a Disc valve will give more hp than a reed will., which is the path Yamaha choose to use to stay competitive with Aprilia.
Funny enough when they made the origional NSR they played with lots of bores and strokes, I was stunned to learn they would at the time have preferred the 56x50mm but didn't want to compromise width on the first design NSR500.
They (at the time) relied on the tech of materials to achieve the same revs with a longer stroke. time has proven a square engine is the best compromise (at this time anyway.)
338364
What i was meaning is i think Honda designed the twin crank NSR250 to bias towards aerodynamics rather than HP. (twin crank and side radiators)
Another interesting snippet from Spencer was he raced and won in one GP on a two up crank configuration, at least three years before Honda decided to standardize the layout. (which is a shame)

[JanBros]

Anyone happen to know the radius of the dome piston for a CR250 (05-07)

3mm dome height

http://www.mitaka.co.uk/HONDA%20PISTONS/PT.05CR250.htm

[F5 Dave]

. . .
A lot of people say Honda should have won GP bike classes as they used huge resources and money i dont really find that rings true when you look at the size of the crew Kenny Roberts had compared to HRC.
At the track or at the factory?

[husaberg]

At the track or at the factory?
At the track Team Roberts would have outgunned HRC by 10:1 Even Kocinski said the same.
I cant remember what he said, but is was something like "look arround team roberts has 80 people HRC 10 and we are still getting smoked....
HRC was big of course about 400 people, but they also did a lot of other stuff, trails, MX and Superbike plus building the customer GP bikes etc.
Aprilia out of a total workforce of 450 i understand had about 62 people in the race program.
I have no idea what Yamaha had them but i know they have 67 engineers back in japan on the YZRm1 MotoGP team alone.
Plus 17 in italy and 55 at each GP.
https://www.cycleworld.com/2014/12/08/yamaha-motor-racing-headquarters-visit-in-italy-by-the-numbers#page-18

[TZ350]

338367

Got my Speeduino fuel injection CPU kit. Put it together and started to find my way around it and understand its methodology.

338366

Interesting system. It has staged injection but instead of it being the small or large injector the Speeduino fires both together but varies the on time of them individually to suit.

[TerraRoot]

Anyone found a good supply of 45C-50C thermal switches?

attempting to make up a simple coolant pump kit for my self and a friend, pump relay wiring all sorted, best switch i could find was a tridon TFS155, but at M16 it's a bit like shoving a pineapple up your nose. TFS242 is much better, but at 200€ i'd rather the pineapple.

links:
http://www.tridon.com.au/products/Tridon/35/483/switches-and-sensors/2014/thermo-fan-switches/1128/TFS155
http://www.tridon.com.au/products/Tridon/35/483/switches-and-sensors/2014/thermo-fan-switches/422489/TFS242

[husaberg]

Anyone found a good supply of 45C-50C thermal switches?

attempting to make up a simple coolant pump kit for my self and a friend, pump relay wiring all sorted, best switch i could find was a tridon TFS155, but at M16 it's a bit like shoving a pineapple up your nose. TFS242 is much better, but at 200€ i'd rather the pineapple.

links:
http://www.tridon.com.au/products/Tridon/35/483/switches-and-sensors/2014/thermo-fan-switches/1128/TFS155
http://www.tridon.com.au/products/Tridon/35/483/switches-and-sensors/2014/thermo-fan-switches/422489/TFS242
https://www.jaycar.co.nz/passive-components/circuit-protection/thermal-switches-fuses/c/202E
http://www.autospeed.com/cms/A_109623/article.html

if you want to get real tricky
http://www.autospeed.com/cms/article.html?&A=112691
http://www.autospeed.com/cms/A_111550/article.html?popularArticle

[TerraRoot]

Thanks, but most of those are not for coolant? if i stuck one on outside of the head, engine be melted by the time the outside got to 50C!

autospeed seems interesting, I'll blow the rest of friday reading it :)

[husaberg]

Thanks, but most of those are not for coolant? if i stuck one on outside of the head, engine be melted by the time the outside got to 50C!

autospeed seems interesting, I'll blow the rest of friday reading it :)
you just place it on a blank plug temp is temp. as long as it a congruous it maters not if its water or air as long as its in contact with a decent conductor. and shielded from outside airfow etc
have a look at this pic
http://cdn3.volusion.com/pjhsw.lyxsc/v/vspfiles/photos/SWI-2000075-5S.jpghttp://cdn3.volusion.com/pjhsw.lyxsc/v/vspfiles/photos/SWI-2000075-4S.jpghttp://cdn3.volusion.com/pjhsw.lyxsc/v/vspfiles/photos/SWI-2000073-2T.jpghttps://images-na.ssl-images-amazon.com/images/I/41G5z6vdXwL._AC_SR160,160_.jpghttps://images-na.ssl-images-amazon.com/images/I/411amAwOlKL._AC_SR160,160_.jpg

if you want simple
https://www.vdo-gauges.com/sensors/temperature-sensors-switch/temperature-switch-120-c-common-ground-switch-point-55-c-m14x1-5.html

[TerraRoot]

I could bond the cheap it to an aluminium m8 or m10 bolt, and with the bolt sticking out about half the hose diameter into the coolant flow, it would probably work perfectly fine, thanks Husa!

[katinas]

Thanks Husa, again very interesting info and Spencer's win with two crank engine really mysterious.

About carbon wheels, they really made second version CFRP wheels for Eddie, new dimension - 3.50x17 and this new version was a one piece molded spoke plate part, differs from previous combine of boomerang type spoke plates. Eddie used them two times, Hockenheim- second, Rijeka -third, but later stick to 3.87x16 magnesium, until the end of 1989. Maybe Gardner used Spencer's carbon front wheels as they was 3.75x16 at Donington and Anderstorp -third .
Add photo of NS 500 with ULF ( Ultra Light Frame) carbon frame and carbon fork tube 6.15mm thick, 41,3mm dia.

[Norman]

Has anyone tried to put a thin divider into the A-port as per the attached second picture? Let say out of 0,5 mm aluminium. I was thinking that it might help to decrease the short circuit of fresh mix into the exhaust by straightening and force more of the flow in the port angle direction? Could it make a performance difference? (More or less flow will also go straight at the section with the curved arrows).

[wobbly]

HH did that on several replacement cylinders , but I dont know how much the guide has a positive influence on directional control Vs extra wall area and flow disturbance.

[F5 Dave]

At the track Team Roberts would have outgunned HRC by 10:1 Even Kocinski said the same.
I cant remember what he said, but is was something like "look arround team roberts has 80 people HRC 10 and we are still getting smoked....
HRC was big of course about 400 people, but they also did a lot of other stuff, trails, MX and Superbike plus building the customer GP bikes etc.
Aprilia out of a total workforce of 450 i understand had about 62 people in the race program.
I have no idea what Yamaha had them but i know they have 67 engineers back in japan on the YZRm1 MotoGP team alone.
Plus 17 in italy and 55 at each GP.
https://www.cycleworld.com/2014/12/08/yamaha-motor-racing-headquarters-visit-in-italy-by-the-numbers#page-18

Yes my point was despite the numbers at the track they were still working with what resources Yamaha saw fit to develop the base engines.

[diesel62]

338367

Got my Speeduino fuel injection CPU kit. Put it together and started to find my way around it and understand its methodology.

338366

Interesting system. It has staged injection but instead of it being the small or large injector the Speeduino fires both together but varies the on time of them individually to suit.I think that the injector strategy will be to stop the hesitation or step you would get starting the second injection. It will never be clean or controlled on the initial start.


Sent from my SM-P555 using Tapatalk

[husaberg]

Yes my point was despite the numbers at the track they were still working with what resources Yamaha saw fit to develop the base engines.
As were Honda, Its hard to say how many people Yamaha had working on the bikes but id hazard a guess if you added up the total it was similar to Honda.
HRC certainly never had the track presence and staff at the track team Roberts did. Despite not using Ohlins who had their own technical support which Roberts also used.
The Yamaha staff at the track were mainly technical support.
I think you will also find Kanemoto developed his own bikes despite them being works Hondas as well.

[Flettner]

another step. Machining the cylinder to take the injectors now also. Don't seem to get much workshop time these days.
https://youtu.be/bhKrRlZxomc

[TZ350]

https://youtu.be/bhKrRlZxomc

That is very clever. I love it.

[husaberg]

Thanks Husa, again very interesting info and Spencer's win with two crank engine really mysterious.

About carbon wheels, they really made second version CFRP wheels for Eddie, new dimension - 3.50x17 and this new version was a one piece molded spoke plate part, differs from previous combine of boomerang type spoke plates. Eddie used them two times, Hockenheim- second, Rijeka -third, but later stick to 3.87x16 magnesium, until the end of 1989. Maybe Gardner used Spencer's carbon front wheels as they was 3.75x16 at Donington and Anderstorp -third .
Add photo of NS 500 with ULF ( Ultra Light Frame) carbon frame and carbon fork tube 6.15mm thick, 41,3mm dia.
I can only go off what was in here
Attachements to follow.
338397338396338399338398
I am not sure if i have the motocourse for that year or not do you have it?
Re the Spencer win it was with a two up 180 crank engine but he tested the twin crank as well i think both are in the spencer 5 part series buried, i only noticed it the second time i had read it.
https://www.cycleworld.com/2013/08/12/on-the-record-freddie-spencer-interview-part-one-of-five
okay not in there
It was 85 at the French GP. although it could have been a all fire within 90 degree big bang as well he said it sounded flat and powered out better much better and lead to the big bang, I asumed it was a two up whch was the Next step Honda took but the sound pitch goes down from the 90 degree even fire to the 180 two up to the big bang.

If i can get access to my PC tonight i will put a few bits together.
Horike designed the 85 250 He was a young engineer, and the only thing he'd done before that was to design the carbon-fibre wheel Spencer crashed on at Kyalami.
But looking at the source of my info for th eLawson wheels it was Cathcart lol
Anyway i see your carbon frame RS500 and raise you a early steel framed one
338404338405
I cant imagine the CF one would have lasted long with the vibes of the NS500.
Honda had to keep beefing up the frames as it was.
From what i have read when Spencer went back to the three after the upside down failed to be any good the new NS500 engines would not fit the frames they had as Honda had changed the engine that year and ERv had to modify the old frames to fit the new engines.

[Norman]

HH did that on several replacement cylinders , but I dont know how much the guide has a positive influence on directional control Vs extra wall area and flow disturbance.

Thanks for the reply, Wobbly. I was thinking that the divider should begin at the upper part of the transfer, be very thin, and end 1-2 mm from port window. It must be pushed/tweaked in there and fastened somehow, small welds or high temp paste/glue possibly. Well, I will keep it on my five year "to do list", with the risk it's just another "schnapps idee". :laugh:

[husaberg]

Freddie doing the double
Quite a few intersting bits in it.
338407338408
I will fix it later A3 wasn't a great idea
click three times

[peewee]

I've been racing model boats a long time. In 3.5 to 15cc glow ignition engines we run 50 to 60% nitro with around 20% synthetic oil. Castor oil doesn't mix with high nitro, but castor/synthetic blends are also used. The oil is more for sealing the ringless pistons than for lubrication. Record setting engines often run up to 80% nitro. Other exotic chemicals like propylene oxide have been added in small amounts in the past. Raising the nitro % requires different head volume and some pipe length adjustment. It doesn't increase the rpm, but the boats can run bigger props at the same rpm. As was pointed out before, the nitro increases MEP and therefore torque.

In 26 to 36cc spark ignition, gasoline engines it was found that doubling the recommended oil mix increased power. Again, I suspect most comes from improved sealing of the single ring piston. By the way, it was common with older style 2 ring pistons to remove the bottom ring for more power.

We did a series of dyno tests on a 26cc engine with various fuels. See below. We found that it was hard to beat the standard pump gasolines even with added nitro and/or ethanol and methanol. Nitro mixes very well with ethanol containing "gasoline". Even Coleman fuel at 50 octane ran well. The reason was we didn't/couldn't change the combustion chamber volume, pipe, or ignition timing. All we did was richen the needle settings for peak power. Methanol and nitro fuels have a lot lower exhaust temperatures and need a different pipe. Nitro burns slower and probably could use more advance. The compression ratio of these industrial engines with one piece head and cylinder designs already have too low compression ratios. Head button engines have more power out of the box. We ran some nitro/methanol fuels in a head button engine briefly. The engine ran fine on 15% nitro, but burned off the plug electrodes on 40% nitro. Again we didn't try to optimize the engine for the different fuel since the race rules specify "gasoline". We did run VP's U-2 for record setting. That fuel was pretty far from pump gasoline.

Lohring Miller

337601

do you know of any tests to see what affect a high oil content has on combustion in a spark engine ? since so much liquid is put in the cyl, likely only a small amount is vapor. some of the liquid will eventually vaporize but I wonder if high oil content has any influence on this, one way or the other. the other thing I was thinking, nitro is adding alot of internal load on parts, im wondering if alot of oil can act as a cushion in a spark engine with typical roller or ball bearings. also I think methanol and nitro might be strong solvents trying to wash down everything they contact, so maybe alot of oil helps in this regard also. I was considering lowering my oil content a bit (16% currently) but im having second thoughts whether that's a good idea or not. not to mention if a viscous mix helps a glow engine piston seal better , then maybe it can help a ringed piston seal better also

[TZ350]

do you know of any tests to see what affect a high oil content has on combustion in a spark engine ?

Looks like more oil = more power.

Ok, not a test as such, but by using the Google "Site:" Search option. oil power site:https://www.kiwibiker.co.nz/forums/showthread.php/86554-ESE-s-works-engine-tuner?

I got these results.

338411

[lohring]

We actually did a few tests on oil mixes over the years. Mostly we relied on others experiences, though. One test on a 35 cc disk valve race engine is posted below. I believe that's the most oil we ever tried. Normally we ran between 8 and 10 oz per US gallon. It looks like in this engine more oil helped the power a little except at the very top end. It's only one test on one engine, though. I feel the main effect is better sealing, even with ringed pistons. Synthetic oils seem to mostly burn up because the exhaust is fairly clean.

Lohring Miller

338419

[lohring]

Has anyone tried to put a thin divider into the A-port as per the attached second picture? Let say out of 0,5 mm aluminium. I was thinking that it might help to decrease the short circuit of fresh mix into the exhaust by straightening and force more of the flow in the port angle direction? Could it make a performance difference? (More or less flow will also go straight at the section with the curved arrows).

Model engines try similar things. Often I think the fancy porting is more for advertising than real power. We actually tested one of these modifications and did find more power on a 35 cc engine. Below is a picture of a Novarossi piston and sleeve from a 3.5 cc engine.

338420

Below is a series of liners we tested for a 35 cc engine. The second sleeve from the left produced the most power. I think the small cuts encouraged the flow at the front of the transfer to aim more upward over the exhaust. The tops of the transfers were otherwise flat and the transfer passages were poorly shaped, not tea cupped.

338421

Lohring Miller

[katinas]

Freddie doing the double
Quite a few intersting bits in it.
338407338408
I will fix it later A3 wasn't a great idea
click three times

No problems with A3, as it very interesting.
I found only one photo from 1985 Le Man race with Spencer's NSR 500, and not sure , but exhaust looks in strange position, not like on std. But difficult to say, as bike angle in photo is not very informative.
Other photo from 1985 tests in Japan with 180 firing NSR 500, but cant say about crank.

[tdc211]

Has anyone tried to put a thin divider into the A-port as per the attached second picture? Let say out of 0,5 mm aluminium. I was thinking that it might help to decrease the short circuit of fresh mix into the exhaust by straightening and force more of the flow in the port angle direction? Could it make a performance difference? (More or less flow will also go straight at the section with the curved arrows).

Just use epoxy. Prep it well. I use a green marine epoxy.
I cure cylinder in oven at 150. Never has come out. Grind A angle any thing you want after cured. Keep epoxy away from piston about. .15mm .i use very fine grinding wheels here.
Only time it has come out ,is when the cylinder needs a plate after lots of hrs,and the platers grind it out.

You prep it right.
It will stay . It helped my curve every where. Bottom to top.

[husaberg]

No problems with A3, as it very interesting.
I found only one photo from 1985 Le Man race with Spencer's NSR 500, and not sure , but exhaust looks in strange position, not like on std. But difficult to say, as bike angle in photo is not very informative.
Other photo from 1985 tests in Japan with 180 firing NSR 500, but cant say about crank.
Most of it is translated
338428338429338430338426338427

[husaberg]

It does weird things in press reader with text?
Oguma

[husaberg]

As above....

[husaberg]

Doohan
I missed the original mag.
338444338445338446338447338448338449

[katinas]

Info from NSR 500 90'-94' specifications, it coud be interesting.

For vertical cylinders (1 and 3) exhaust - Titanium 0.8 mm header, 0.6 mm other.
Lower cylinders (2 and 4) exhaust - Steel 0.7mm header, 0.6mm other
Maybe because of dfferent material thermal properieties or still avoided cracking on more complex lower pair.

And different squash (I'm not sure): on 93'-94' vertical -0.56mm, lower-1.25mm. Maybe different cylinders pair position or crank-firing-load route or teperature difference and vertical cylinders higher elongations , interesting.

[Frits Overmars]

Info from NSR 500 90'-94' specifications, it coud be interesting. For vertical cylinders (1 and 3) exhaust - Titanium 0.8 mm header, 0.6 mm other. Lower cylinders (2 and 4) exhaust - Steel 0.7mm header, 0.6mm other
Maybe because of dfferent material thermal properieties or still avoided cracking on more complex lower pair.The main reason for using different materials for the upper and lower pipes was not the thermal properties of those materials, but the shapes of the pipes.
The lower pipes required some twisting and turning in order to get them past the rear tire and preserve some cornering clearance. Using stamped segments was the easiest way to build them. But you cannot stamp titanium, it's too stubborn, so steel was used for those lower pipes.
The only curved sections in the upper pipes were the headers, which were produced as separate castings, so the remainder of the pipes could be dead straight.
This enabled Honda to build those upper pipes out of rolled titanium segments.
338467 338466

[Dutch Fisher]

And different squash (I'm not sure): on 93'-94' vertical -0.56mm, lower-1.25mm. Maybe different cylinders pair position or crank-firing-load route or teperature difference and vertical cylinders higher elongations , interesting.



Squish?? err nope チャンバ means chamber, that #1 to#4 is the weight of the bare expansion chambers per cyl number
The two rows above are サイレンサ means sliencer, so material and weight of the silencers.

[koenich]

But you cannot stamp titanium, it's too stubborn, so steel was used for those lower pipes.
Nope, totally possible to deep draw titanium.

[katinas]

Squish?? err nope チャンバ means chamber, that #1 to#4 is the weight of the bare expansion chambers per cyl number
The two rows above are サイレンサ means sliencer, so material and weight of the silencers.

Yes, of course, thanks

[jonny quest]

Frits, Honda CRF250 and CRF450 2017-18. OEM titanium stamped gas tanks. They're pretty!

[Norman]

Just use epoxy. Prep it well. I use a green marine epoxy.
I cure cylinder in oven at 150. Never has come out. Grind A angle any thing you want after cured. Keep epoxy away from piston about. .15mm .i use very fine grinding wheels here.
Only time it has come out ,is when the cylinder needs a plate after lots of hrs,and the platers grind it out.

You prep it right.
It will stay . It helped my curve every where. Bottom to top.

Thank's for the tip. I will first do the welding I can on the cylinders. Have I understood it right that you actually tested to put something like an extra divider?

[lodgernz]

I need some advice please. Below are photos of my 50's exhaust port as stock. The narrow point at 13 to 15 mm from window centre is only 75% of the window area after downdraft correction.
Should I expand this by raising the roof and/or lowering the floor, or is it serving a useful purpose by accelerating the exhaust stream? The downdraft angle is 25º at the top of the port, 4º at the bottom.
I can increase the window area some, which will make this restriction worse relative to the window area.

338468338469

[wobbly]

The best duct geometry for a low bmep single port is to have around 90% area at the face of the cylinder exit.
Then a transition in the spigot out to 100% that is then the header area.
For high bmep 3 port setups the exit area drops to 75% , I demonstrated the effectiveness of this not long ago with a dyno sheet on here , with the biggest power increase I have seen
in all my hundreds of dyno runs of the 125 kart engines.

[lodgernz]

The best duct geometry for a low bmep single port is to have around 90% area at the face of the cylinder exit.
Then a transition in the spigot out to 100% that is then the header area.


Thanks Wobbly. I plan to fit an insert to achieve that 90% at 1.5 x bore, and the expansion back out to 100% at 2 x bore, as you have advised.
My question was more about the effect of the 75% restriction that occurs quite close to the port window. I would have thought that a consistent steady reduction from port to 90% is ideal, rather than a wildly varying CSA.
I can probably achieve that, but I'm just wondering if raising the roof and lowering the floor at the tight point is going to have a negative effect. You have written many times about the "ski slope" and it's beneficial effects.

[wobbly]

Yes, the combination of a 25* downslope roof and a ski jump floor that has a gradual area reduction is for sure the go.
But this is mainly directed at reducing the CSA of the duct where the Aux ports blend into it .
Here is a cross section of the cylinder I modified to incorporate the side duct ears and the 75% area at the exit.
The roof starts at 25* then flattens out , and the floor slopes away more past the side duct entry area.

[lodgernz]

Yes, the combination of a 25* downslope roof and a ski jump floor that has a gradual area reduction is for sure the go.
But this is mainly directed at reducing the CSA of the duct where the Aux ports blend into it .
Here is a cross section of the cylinder I modified to incorporate the side duct ears and the 75% area at the exit.
The roof starts at 25* then flattens out , and the floor slopes away more past the side duct entry area.

Thanks again Wobbly. The roof will be raised and the sides of the port will get "ears". Can't go any wider as it's already 72% of bore.

[jonny quest]

I used to do 82% on single exhaust ports. Basically a mild bridge port shape. Works well and doesn't ear rings. But bottom of port needs to be around 68%.

[lodgernz]

I used to do 82% on single exhaust ports. Basically a mild bridge port shape. Works well and doesn't ear rings. But bottom of port needs to be around 68%.

Interesting. Might be able to get it out to 75% before I break through the water jacket.

[F5 Dave]

I always used 75 on the RG50, just be careful chamfering.

[dutchpower]

Wobb can you tell me more about this situation

Thanks

[husaberg]

Early HRC
338492338493338494

BSL500 in Cycleworld
338495

Kawa X09 at Daytona (i added the pics to fill in space although the cut off one i think is Aaron Slight judging by the leathers Team Moving)
338497338496
The deisgn never made decent power with it breating through the bottom of the cases
http://1.bp.blogspot.com/-rYf6KffxOGE/Ty2B7mkw5II/AAAAAAAAA70/VPLwjTKyPUE/s1600/001-Copy.jpg

[ken seeber]

another step. Machining the cylinder to take the injectors now also. Don't seem to get much workshop time these days.
https://youtu.be/bhKrRlZxomc

Fletto, congratulations on the near completion of your creation of the symmetrical circumcision device. Well done, although a question:

Can you, without the introduction of a second servo or a manual belt shift, vary the opening gap to be advanced ar retarded from the shown mid position?

DANGER WARNING: you kiwis should be very aware of such a gizmo cos it does get so cold over there…:Oops:

[Flettner]

it may not be readily apparent but the tooth belt drive has different numbers of teeth for each Gib. So opening gib moves less than the trailing gib.
This linked belt is just to get the project up and running, ulitamtely both ( or at least one) Gib will be servo driven.
Gib opening will be throttle, Gib positioning will be decided by ECU for best timing for given rpm and other inputs.

[wobbly]

Dutch, what you are seeing is the wave action Mach number as it exits the stinger.
The wave enters the pipe at EPO , then with a finite velocity thru the hot gas it takes until around BDC for that front to be detected at the outlet.
I must say I have never looked at that particular trace before , as I cant see it as any use to designing an optimized pipe .
So I concentrate on the Mach in the cylinder duct exit area , and the Mach in the middle of the stinger venturi.
As you can see if you plot this against Mach number , the wave action in the stinger has alot of energy and the reflections off atm bounce up and down its length with a frequency dependent upon
this length.
But with a proper nozzle , using a sharp angled step into the stinger tube , the wave action amplitude is reduced when it returns - and thus lessens the interference with the main reflection wave inside the rear cone.

[tdc211]

Thank's for the tip. I will first do the welding I can on the cylinders. Have I understood it right that you actually tested to put something like an extra divider?

not sure why you want try a extra divider here, I was talking on A port front hook angle.
I tried A port in many different widths and tried many front to rear hook angles.
problem I see for most is trying to grind in enough rear angle. That is, if your cylinder is lacking here. Like mine was .
I highly doubt its worth the time to test a divider here.
But I bet its worth the time to test the rear direction on the front A port hook.
as Jan said somewhere, this is maybe the touchest spot in the cylinder.

[Lightbulb]

Thanks to Wobbly, the 75% rule he does totally transformed an engine I was working on in 04. We took it from 3.25hp aprox, to 4.3 hp aprox with the exhaust insert and a new pipe. Without the insert with the 25% area reduction, it did not work very well at all, and could only run other pipes that limited the power output to the 3.25 hp range.
I learnt a lot from those tests. Thanks again Wobbly.

[TZ350]

I was talking on A port front hook angle. I tried A port in many different widths and tried many front to rear hook angles. problem I see for most is trying to grind in enough rear angle. That is, if your cylinder is lacking here. Like mine was. But I bet its worth the time to test the rear direction on the front A port hook. as Jan said somewhere, this is maybe the touchiest spot in the cylinder.

Is this the angle you mean?

338512

[peewee]

Looks like more oil = more power.

Ok, not a test as such, but by using the Google "Site:" Search option. oil power site:https://www.kiwibiker.co.nz/forums/showthread.php/86554-ESE-s-works-engine-tuner?

I got these results.

338411

I was thinking more about how the oil may affect the combustion process, rather than sealing the rings. with methanol or nitro, where so much of the fuel in the cylinder is likely still liquid , atleast initially. I think some how the liquid would need to be converted to vapor to be combusted. would the high oil content retard this process ?? ill probly never know for sure since I don't have the meens to investigate it with any certainty.

but im going to try something different tomorrow and see if theres any noticeable difference in the butt dyno.

until now I had always been using this mix totaling about 1gal

nitro 30% - 38.5oz
oil 16% - 20.5oz
methanol 54% - 69oz

ive mixed this new stuff to try tomorrow

nitro 31% - 40oz
oil 12% - 16oz
methanol 57% - 73oz

before i added oil I checked the mix with hydrometer and its pretty close to the same density (34% at 85F ) as the previous mix I had been using, which is what I was shooting for. the difference now is each intake cycle I should have a bit more volume of nitro and methanol enter the cylinder, at the expense of less oil of course. lets assume there is a slight loss of power from less oil / less viscous mix. im thinking the extra nitro and meth would make up that lost power and add add alittle more. i think its worth a shot to see anyways. maybe the difference will be to small to tell


about the hook ports. it seems like they wouldn't be very effective. if possible maybe try to put a radiused side wall instead. like this vinamold from a standard ktm barell

[jonny quest]

Husaberg and Katinas are good at this... engine pics of the early NS500 and NSR500. apparently they were rotary valve. Curious where Honda put the rotary valves.

[husaberg]

Husaberg and Katinas are good at this... engine pics of the early NS500 and NSR500. apparently they were rotary valve. Curious where Honda put the rotary valves.
No rotary valves on the NS or NSR500 that i have ever seen
The NS was cylinder reed and the NSR was Case reed
Honda did do a single with rear mounted rotary valves though.
Honda being honda may have tried discs on some prototype bikes but were committed to using reeds.
338519I actually thought there way have been a rc125m twin version with discs as well as a single 250
Yamaha did do a Disc valve V four.
338520338521
If kenny had stuck with the older but reliable side disk mounted 4 he might have won.
That year on a old design square 4 using old parts Crosby finished second to Kennys Fourth.
According to legend is was hated by Yamaha and the then lead designed asked to be present when they were crushed at the end of the season.

[lodgernz]

I suspect nobody here has ever seen one of these:

http://japan.webike.net/moto_news/phantom-motorcycle-kawasaki-2-stroke-monster-square-four-750-tartar-steak/?utm_source=webikestyle&utm_medium=motonews&utm_campaign=20180818

[F5 Dave]

I'd seen the Yamaha proto but that's a new one on me. Kewl!

[husaberg]

I suspect nobody here has ever seen one of these:

http://japan.webike.net/moto_news/phantom-motorcycle-kawasaki-2-stroke-monster-square-four-750-tartar-steak/?utm_source=webikestyle&utm_medium=motonews&utm_campaign=20180818


I'd seen the Yamaha proto but that's a new one on me. Kewl!
I have posted it before in oddballs there was a race version it wasn't a true square four. it was Trapezoid
I will post the race version later
338523338524

Edit well it was old race multis thread
https://www.kiwibiker.co.nz/forums/showthread.php/151865-Old-multi-cylinder-bikes-of-the-50s-to-later-on-Japanese-British-Euro-etc?p=1130655389#post1130655389

Edit again it was both the multis and the oddballs threads Grump posted a pic as well
https://www.kiwibiker.co.nz/forums/showthread.php/171300-Oddball-engines-and-prototypes?p=1130991542#post1130991542

Edit again i have actually had an album dedicated to it
https://www.kiwibiker.co.nz/forums/album.php?albumid=5045

[husaberg]

338525338528338527338526
338532338533

[TZ350]

338529
if possible maybe try to put a radiused side wall instead. like this vinamold from a standard ktm barell

Thanks for the heads up, I wasn't sure what tdc211 meant before about "A port front hook angle" it looks like the Honda cylinders, MC21 and NF4 et all already have them.

338530

[Norman]

not sure why you want try a extra divider here, I was talking on A port front hook angle.
I tried A port in many different widths and tried many front to rear hook angles.
problem I see for most is trying to grind in enough rear angle. That is, if your cylinder is lacking here. Like mine was .
I highly doubt its worth the time to test a divider here.
But I bet its worth the time to test the rear direction on the front A port hook.
as Jan said somewhere, this is maybe the touchest spot in the cylinder.

If a good rear angle (which I think I can do) on the A-port would fix the short cut to a low level, then no, why should I put in an extra divider. If not, my thought was that it would help the directional flow stability out from the A-port, particulary the section closest to the exhaust port, such that the flow would have more difficult to make a U-turn. A thin plate ending a mm into the port should not decrease the flow area. But maybe a good rear angle and enough material in the cylinder wall section in front of the A-port, towards the exhaust, eliminates the problem to a level where there is no real justification to try to do anything else.

[TZ350]

A thin plate ending a mm into the port should not decrease the flow area. But maybe a good rear angle and enough material in the cylinder wall section in front of the A-port, towards the exhaust, eliminates the problem to a level where there is no real justification to try to do anything else.

Yes I understand properly now. Thanks.

[jasonu]

I suspect nobody here has ever seen one of these:

http://japan.webike.net/moto_news/phantom-motorcycle-kawasaki-2-stroke-monster-square-four-750-tartar-steak/?utm_source=webikestyle&utm_medium=motonews&utm_campaign=20180818

Shame they didn't make a water cooled H2.

[F5 Dave]

If a good rear angle (which I think I can do) on the A-port would fix the short cut to a low level, then no, why should I put in an extra divider. If not, my thought was that it would help the directional flow stability out from the A-port, particulary the section closest to the exhaust port, such that the flow would have more difficult to make a U-turn. A thin plate ending a mm into the port should not decrease the flow area. But maybe a good rear angle and enough material in the cylinder wall section in front of the A-port, towards the exhaust, eliminates the problem to a level where there is no real justification to try to do anything else.
So being that the transfers end up to some extent becoming exhaust ports breifly, resilience of that thin plate? It would be an unfortunate event if it dislodged.

[Norman]

So being that the transfers end up to some extent becoming exhaust ports breifly, resilience of that thin plate? It would be an unfortunate event if it dislodged.

I would first try to at least spot weld it in place, to secure. Yes, it would be hit by exhaust gas, but also cooled by fresh mix. Heat is also moving away through the welds to the transfer roof and bottom. I think that it should be ok.

[wobbly]

Beta, as I cant post a .jpg in a PM here is the answer to your question.
If you can drop the duct roof srarting from where the Aux ports enter the EX then you will get the huge power increase as I did.
I also dropped the side ducts back near the centerline of the lower exit area.
You have to be very careful with a stock casting not to make the side ducts too deep, or you get into water.

[tdc211]

Is this the angle you mean?

338512

yes! yes yes

My 1st yes was to short to reply

[tdc211]

Thanks for the heads up, I wasn't sure what tdc211 meant before about "A port front hook angle" it looks like the Honda cylinders, MC21 and NF4 et all already have them.


338530

Not sure if i ever said anything about a Honda.
I think one of best A ports for rear direction. Is a kx 85/100. Compete junk other than that. And those things make easy pwr. Spin like crazy with long piston to diffuser. Ktm 105 does not make easy pwr. It hate long piston to diffuser

the new 2018 ktm cylinder which looks like my epoxy cylinders
Only better as they tightened up bottom corner of ex port.
Finally have new 18 105 cylinder on my dyno now. Just released
Now that i know what i know. 1st thing i would do is weld up bottom corner of export and get good rear direction in A port


New cylinder in pic
Its a beast. 338569
Pipe testing next few days. I have many pipes,also just built a new pipe.

I should add. There a bunch of guys on here. Some with ok cylinders.Some that are not. I know for sure. bad A direction is just terrible. But it can be fixed cheaply/ fast and is reliable if you prep well and use epoxy. Idk know why ,the hot gases dont seem to affect it .

[Muhr]

Has anyone tried to put a thin divider into the A-port as per the attached second picture? Let say out of 0,5 mm aluminium. I was thinking that it might help to decrease the short circuit of fresh mix into the exhaust by straightening and force more of the flow in the port angle direction? Could it make a performance difference? (More or less flow will also go straight at the section with the curved arrows).

Do not know if this was what you meant to do, but what I can see it seems to mostly create resistance.
(in compressible CFD)

[Norman]

Do not know if this was what you meant to do, but what I can see it seems to mostly create resistance.
(in compressible CFD)

Yes, in principle yes, maybe a little longer divider into the port. But, it seems not to give any positive effect..Perhaps it differs depending on what vertical layer and the dP/flow you are looking at. But no, I think the idea could be put aside for now. Thank you for taking the time to set the case up in the CFD!

[RomeuPT]

Not exacly a flat top...

338571

[katinas]

Thanks to Wobbly, the 75% rule he does totally transformed an engine I was working on in 04. We took it from 3.25hp aprox, to 4.3 hp aprox with the exhaust insert and a new pipe. Without the insert with the 25% area reduction, it did not work very well at all, and could only run other pipes that limited the power output to the 3.25 hp range.
I learnt a lot from those tests. Thanks again Wobbly.

Another agree.

Honda CR 125 reed type cylinders , changed every year from 1981 to 1986. On first water cooled 81‘ CR 125, Honda made huge volume transfer ports with big transfer windows and these cylinders was used on early RS 125 model.
82‘ reduced transfers ports size, but trans windows left unchanged.
83‘ lowered transfer windows and this, together with exhaust windows size, remains almost unchanged until the last 86‘ reed cylinder type engine, even after stroke changed (from 50.6mm to 54mm) in 85‘
Exhaust windows area, from 81‘ to 86‘, very similar, but ex duct last dimension changed 3 times:
81‘-82‘- oval shape 35x39 mm,
83‘- oval 37x39mm
84‘-85‘ round 40mm,
86‘ -round 37mm.

One of the many tests this year was with CR 125 84‘ cylinder original 40mm ex duct and modified, with insert 34x38mm (add photo) on my NS engine. With insert, when engine is on the pipe, power feels sharper, especially at 10500 rpm. Can‘t show anything, because tested only on the road, but very nice to feel changes in good way with hands.

[husaberg]

Another agree.

Honda CR 125 reed type cylinders , changed every year from 1981 to 1986. On first water cooled 81‘ CR 125, Honda made huge volume transfer ports with big transfer windows and these cylinders was used on early RS 125 model.
82‘ reduced transfers ports size, but trans windows left unchanged.
83‘ lowered transfer windows and this, together with exhaust windows size, remains almost unchanged until the last 86‘ reed cylinder type engine, even after stroke changed (from 50.6mm to 54mm) in 85‘
Exhaust windows area, from 81‘ to 86‘, very similar, but ex duct last dimension changed 3 times:
81‘-82‘- oval shape 35x39 mm,
83‘- oval 37x39mm
84‘- round 40mm,
85‘-86‘ -round 37mm.

One of the many tests this year was with CR 125 84‘ cylinder original 40mm ex duct and modified, with insert 34x38mm (add photo) on my NS engine. With insert, when engine is on the pipe, power feels sharper, especially at 10500 rpm. Can‘t show anything, because tested only on the road, but very nice to feel changes in good way with hands.

Katinas do you have measurements for the cylinder widths and stud spacing for the 85-86 CR125 Cylinders.

[peewee]

Looks like more oil = more power.

Ok, not a test as such, but by using the Google "Site:" Search option. oil power site:https://www.kiwibiker.co.nz/forums/showthread.php/86554-ESE-s-works-engine-tuner?

I got these results.

338411

well i dont know much more today that i didnt already know couple days ago, except to say that its amazing just how much qauntity of fuel you can put in the engine when theres nitro in the mix. for the hell of it i fully opened all four jets to see what would happen. it didnt flood the crankhouse like you would think. suprisingly it still ran pretty well but after reviewing the video it sounded like over fueling was just starting to creep in, mainly during gear changes when the engine load is breifly absent. still i was quit suprised considering with straight methanol the engine is a blubbering mess once you try to open the third jet

also it seems to run better and have more power if you can manage to get some heat into the engine. say about 130f and above. perhaps this is due to a high heat of vaporization needed for the mix to burn

[Muhr]

Yes, in principle yes, maybe a little longer divider into the port. But, it seems not to give any positive effect..Perhaps it differs depending on what vertical layer and the dP/flow you are looking at. But no, I think the idea could be put aside for now. Thank you for taking the time to set the case up in the CFD!

Here you have a "hook"

[wobbly]

The most powerful RS125 cylinder I did when experimenting with ports and pipes for a Belgian aftermarket supplier , had the duct exit at 41 wide ( the header size ) by 32 high oval.
This transitioned in the spigot to the 41 round , no steps anywhere.
And the 2002 cylinder used in SKUSA racing ( only 40 Hp ) has from memory a 40 by 34 oval exit, and again transitioning this within the spigot , into the SKUSA pipe header gives the best power.

[katinas]

Katinas do you have measurements for the cylinder widths and stud spacing for the 85-86 CR125 Cylinders.


From 83’to 86’ CR 125 cylinder studs spacing is the same (like NS250/400):

Along (between intake and exhaust sides - 79mm. (Yamaha TZ250 DP4 - 78mm)
Crosswise (from side to side) - 96mm. (81’-82’ right front stud is closer to left, so distance -85mm. Yamaha TZ250 DP4 -96mm.)
85’-86’ cylinder height - 98.5mm; 81’-84’ -93mm.
Widest 83’-86’ cylinder dimension crosswise - 116mm.

Widest place between transfer ports from side to side at lower cylinder plane:
81’- 107mm.
82’-86’ - 96-98mm.
All cylinders with iron liners cast in.

Husa, maybe you have some info about Yamaha TZ 250 prototype 82'-83' rotary tandem twin (08KO), looks like experimentation with half rotary OW60 500. Info from Racers magazine.

[husaberg]

From 83’to 86’ CR 125 cylinder studs spacing is the same (like NS250/400):

Along (between intake and exhaust sides - 79mm. (Yamaha TZ250 DP4 - 78mm)
Crosswise (from side to side) - 96mm. (81’-82’ right front stud is closer to left, so distance -85mm. Yamaha TZ250 DP4 -96mm.)
85’-86’ cylinder height - 98.5mm; 81’-84’ -93mm.
Widest 83’-86’ cylinder dimension crosswise - 116mm.

Widest place between transfer ports from side to side at lower cylinder plane:
81’- 107mm.
82’-86’ - 96-98mm.
All cylinders with iron liners cast in.

Husa, maybe you have some info about Yamaha TZ 250 prototype 82'-83' rotary tandem twin (08KO), looks like experimentation with half rotary OW60 500. Info from Racers magazine.

Cheers for that.
I remember there was a TZ that raced here in the 80's that had CR125 cylinders Grump will remember it I think it was Brent Jones?
Ifi t was Brent Jones that would be pretty Ironic as he used to Races a RG500 cylindered (race Bike RG Cylinder not road) on a Kawasaki 125 bottom end (Early KX i think) I think it was made at MClearly's
The forrunner to a lot of bucket racers.
No i have never seen a half a OW60, or heard of it.
I do know that Suzuki made up quarter a RGB racers for Asia.
I have a pic of an engine somewhere.
I put up some of a write up CW did of one of the Daytone overbored bikes big bored OW60 or similar last night.
338585338584338583338588338587338586

[husaberg]

The rest of the OW69
338592338591338590338589338594338593

[husaberg]

Last two
( the text is cut off on the edge as thats How the Cycle World have scanned their mags)
338596338595
If you look at the OW60 i posted a month or two ago they are really just bigger 500 GP bikes
I always thought the overbored bikes they ran in those years were only about 580cc
but 64mmx54mm is about 700cc

[Grumph]

Cheers for that.
I remember there was a TZ that raced here in the 80's that had CR125 cylinders Grump will remember it I think it was Brent Jones?
Ifi t was Brent Jones that would be pretty Ironic as he used to Races a RG500 cylindered (race Bike RG Cylinder not road) on a Kawasaki 125 bottom end (Early KX i think) I think it was made at MClearly's
The forrunner to a lot of bucket racers.


Don't remember a TZ like that - doesn't mean it wasn't done though.
I remember looking at the Brent Jones 125 one friday night in Jacks Yamaha. His dad Craig told me they'd found it in Asia somewhere on one of his race trips, liked it and bought it. Don't remember what the bottom end was. It's vanished now. Probably thrown in a deal with one of the race bikes they've sold overseas.
Craig had a habit of buying bikes on the trips to Malaysia, Singapore and Indonesia. H1R, various early TD/TR Yamahas...All sold now.

[katinas]

Last two
( the text is cut off on the edge as thats How the Cycle World have scanned their mags)
338596338595
If you look at the OW60 i posted a month or two ago they are really just bigger 500 GP bikes
I always thought the overbored bikes they ran in those years were only about 580cc
but 64mmx54mm is about 700cc

Remember one magic motorcycle magazine, from my old shool days, that cousins father gave him when return from USA. One article was about F 750 with all three - Yamaha four, Suzuki and Kawasaki triples. When I be on a visit at his home, I'am do nothing, just siting with this article all day, and this repeated every time when I visited him. Remember, can't understand why Yamaha stopped at 700cc. Nice motorcycle and swingarm.

Interesting how things was going, if Yamaha translated OW60 code for square 60x60mm bore/stroke configuration on OW69.

Add reference from Racers about Yamaha 250 rotary tandem

[husaberg]

Don't remember a TZ like that - doesn't mean it wasn't done though.
I remember looking at the Brent Jones 125 one friday night in Jacks Yamaha. His dad Craig told me they'd found it in Asia somewhere on one of his race trips, liked it and bought it. Don't remember what the bottom end was. It's vanished now. Probably thrown in a deal with one of the race bikes they've sold overseas.
Craig had a habit of buying bikes on the trips to Malaysia, Singapore and Indonesia. H1R, various early TD/TR Yamahas...All sold now.

I looked back through the results i had posted ages ago checked and my hunch was right it was Brent Jones and it was raced at the 84 NZGP and won the 350 GP (that was the year they raced the Street circuit at Syndenham)
the results show it as a TZ250 bitza but else where in the mag it was mentioned as having CR125 cylinders. so it was either short stroked or maybe a bit bigger than 250.
As the CR's didn't have 54mm strokes until the next year.
Any Idea who would know anything about it? Who would be alive out of Jacks Jungle? Is Brent arround?
Aaron slight who i guess would have been lucky to be 18 finished second on a RZ350 and set the fastest lap of the day all classes.
Considering the field that day also included Robert Holden and Rodger Freeth isn't bad.


Remember one magic motorcycle magazine, from my old shool days, that cousins father gave him when return from USA. One article was about F 750 with all three - Yamaha four, Suzuki and Kawasaki triples. When I be on a visit at his home, I'am do nothing, just siting with this article all day, and this repeated every time when I visited him. Remember, can't understand why Yamaha stopped at 700cc. Nice motorcycle and swingarm.

Interesting how things was going, if Yamaha translated OW60 code for square 60x60mm bore/stroke configuration on OW69.

Add reference from Racers about Yamaha 250 rotary tandem
I think i have posted that on another thread. it was i think Cycle and done by Kevin Cameron
Either that or it might still be on my hard drive. I will have look when i get back home.
I thought Yamaha went contra rotating cranks on the other bikes a bit later on than that on the Reed valve bikes at least anyway.

[shnaggs]

Quick question for the knowing.

Take a look at these STA values, its for a newer KTM125. It appears that the exhaust port is on the small side in comparison to the transfers, but the blow down seems good. So does that mean since the blow down is good for 40hp that the engine should make 40hp, or is the Exh port still the limiting factor? As of now on my dyno the bike only makes 36.5hp

Thanks,

[tdc211]

Quick question for the knowing.

Take a look at these STA values, its for a newer KTM125. It appears that the exhaust port is on the small side in comparison to the transfers, but the blow down seems good. So does that mean since the blow down is good for 40hp that the engine should make 40hp, or is the Exh port still the limiting factor? As of now on my dyno the bike only makes 36.5hp

Thanks,

On mine it makes 38 with a known good reed block. Rejetted on pump.
My sta values look a liitke different than yours on a stock cylinder

[shnaggs]

On mine it makes 38 with a known good reed block. Rejetted on pump.
My sta values look a liitke different than yours on a stock cylinder

Thanks for the reply.

Would you mind sharing your STA values?

[jonny quest]

Quick question for the knowing.

Take a look at these STA values, its for a newer KTM125. It appears that the exhaust port is on the small side in comparison to the transfers, but the blow down seems good. So does that mean since the blow down is good for 40hp that the engine should make 40hp, or is the Exh port still the limiting factor? As of now on my dyno the bike only makes 36.5hp

Thanks,

28.3mm ex 43.5mm trans heights 16 SX125. Why are your heights so different?

[Grumph]

I looked back through the results i had posted ages ago checked and my hunch was right it was Brent Jones and it was raced at the 84 NZGP and won the 350 GP (that was the year they raced the Street circuit at Syndenham)
the results show it as a TZ250 bitza but else where in the mag it was mentioned as having CR125 cylinders. so it was either short stroked or maybe a bit bigger than 250.
As the CR's didn't have 54mm strokes until the next year.
Any Idea who would know anything about it? Who would be alive out of Jacks Jungle? Is Brent arround?
Aaron slight who i guess would have been lucky to be 18 finished second on a RZ350 and set the fastest lap of the day all classes.
Considering the field that day also included Robert Holden and Rodger Freeth isn't bad.

Jungle and Brent are both still around. Doubt you'd get much help from either...Brent manages what used to be Canterbury Glass and hasn't been seen near a bike for years. Successful businessman now. Jungle is still Jungle - but worse if anything.
Not surprised at Aaron's speed at Sydenham. Tight bumpy street circuit - a stock RZ well ridden would be better than a TZ around that. I've mentioned Kirby's F1 ride before - gear linkage fell off on the first corner and he finished 4th in the F1 GP using only 2nd gear on an 1100 Suzuki....

[shnaggs]

28.3mm ex 43.5mm trans heights 16 SX125. Why are your heights so different?

Good question! From the factory my 16 SX125 came with the .6mm base gasket. The piston protrudes above the deck by .006" or .16mm. I also used Frits' way of measuring the ports utilizing welding rod at an angle and subtracting the OD of the rod at the given angle.

[jbiplane]

Muscle muffler for 2-stroke boxers

We finally tested it and got 1,5 power increase compare straight pipe exhaust.
Seems 2-stroke motocycle boxers is rare if ever exist. But...

https://www.youtube.com/watch?v=uqCYDpf7WJw

Modeling in Engmod2t

https://www.youtube.com/watch?v=AmYKK7U38JE&t=35s

[wobbly]

The STA values in EngMod are at the crank , and are directly variable by the Combustion Efficiency value entered.
But in any case there will always be a drop in displayed Hp depending on where it is measured.
At the rear wheel on a Dynojet , with the tyre and chain friction involved, as well as the primary drive /cluster , as well as Dynojets well known fudge factor
the reduction is 12.5 to 15% - I have seen this hundreds of times between the calculated power in Engmod and the RWHp figure.
On an inertia dyno with a chain on the countershaft sprocket , as is mostly used on karts , its around 7 -10%.

Re the STA figures for the KTM150 , the value for the Ex port itself is near on irrelevant.
In fact if its small , as in this case , that is exactly what we have been shooting for in the last 10 years - getting the duct volume down , smaller and smaller , by lifting the floor
above BDC and filling in the corner rads below the TPO.
Having the Blowdown and the Transfer STA matching is what is needed where the effective efficiency are both similar.
But this is affected by the scavenging model used to correct the efficiency of say crap transfer ducts , and in this case the transfer STA needs to be lifted above the EX blowdown due
to the real Cd of the ports.

But I just noticed that the STA numbers are generated at 11750 - so this must be used with a kart or road race type pipe , as no way would it be of any use on a MX track , peaking that high.
Then if being used in a kart or road race end use , the power is way low for that rpm , as we get 45 Engmod Hp @ 11750 from a stock 2002 CR125 with just a pipe change.
And that translates to close to 40 Hp at the sprocket.

[F5 Dave]

Mmmm. Fudge Factor.

[dutchpower]

The STA values in EngMod are at the crank , and are directly variable by the Combustion Efficiency value entered.
But in any case there will always be a drop in displayed Hp depending on where it is measured.
At the rear wheel on a Dynojet , with the tyre and chain friction involved, as well as the primary drive /cluster , as well as Dynojets well known fudge factor
the reduction is 12.5 to 15% - I have seen this hundreds of times between the calculated power in Engmod and the RWHp figure.
On an inertia dyno with a chain on the countershaft sprocket , as is mostly used on karts , its around 7 -10%.

Re the STA figures for the KTM150 , the value for the Ex port itself is near on irrelevant.
In fact if its small , as in this case , that is exactly what we have been shooting for in the last 10 years - getting the duct volume down , smaller and smaller , by lifting the floor
above BDC and filling in the corner rads below the TPO.
Having the Blowdown and the Transfer STA matching is what is needed where the effective efficiency are both similar.
But this is affected by the scavenging model used to correct the efficiency of say crap transfer ducts , and in this case the transfer STA needs to be lifted above the EX blowdown due
to the real Cd of the ports.

But I just noticed that the STA numbers are generated at 11750 - so this must be used with a kart or road race type pipe , as no way would it be of any use on a MX track , peaking that high.
Then if being used in a kart or road race end use , the power is way low for that rpm , as we get 45 Engmod Hp @ 11750 from a stock 2002 CR125 with just a pipe change.
And that translates to close to 40 Hp at the sprocket.

Think that's oke wobb

[Niels Abildgaard]

Muscle muffler for 2-stroke boxers

We finally tested it and got 1,5 power increase compare straight pipe exhaust.
Seems 2-stroke motocycle boxers is rare if ever exist. But...


There was many 2 cylinder boxer 2 stroke MCs in DDR.


https://de.wikipedia.org/wiki/MZ_BK_350


It was made as a poor mans BMW with shaft drive because DDR could not make MC chains.
The reaction torque variation from a two stroke boxer is just as nasty as from a single cylinder.
No good for aircrafts either.
Make a V2 instead.

[shnaggs]

The STA values in EngMod are at the crank , and are directly variable by the Combustion Efficiency value entered.
But in any case there will always be a drop in displayed Hp depending on where it is measured.
At the rear wheel on a Dynojet , with the tyre and chain friction involved, as well as the primary drive /cluster , as well as Dynojets well known fudge factor
the reduction is 12.5 to 15% - I have seen this hundreds of times between the calculated power in Engmod and the RWHp figure.
On an inertia dyno with a chain on the countershaft sprocket , as is mostly used on karts , its around 7 -10%.

Re the STA figures for the KTM150 , the value for the Ex port itself is near on irrelevant.
In fact if its small , as in this case , that is exactly what we have been shooting for in the last 10 years - getting the duct volume down , smaller and smaller , by lifting the floor
above BDC and filling in the corner rads below the TPO.
Having the Blowdown and the Transfer STA matching is what is needed where the effective efficiency are both similar.
But this is affected by the scavenging model used to correct the efficiency of say crap transfer ducts , and in this case the transfer STA needs to be lifted above the EX blowdown due
to the real Cd of the ports.

But I just noticed that the STA numbers are generated at 11750 - so this must be used with a kart or road race type pipe , as no way would it be of any use on a MX track , peaking that high.
Then if being used in a kart or road race end use , the power is way low for that rpm , as we get 45 Engmod Hp @ 11750 from a stock 2002 CR125 with just a pipe change.
And that translates to close to 40 Hp at the sprocket.


Thanks for the explanation Wob. I understand that different dynos and whether wheel power or crank power is calculated will make a difference in the power reading.

I'm not too concerned with what my power number is, more just trying to wrap my head around this whole 'black magic' of 2 stroke tuning. See ive been messing about with different inlet valve configurations with no gain to be had. I was thinking that maybe its pointless to be messing around with inlet configs when the exhaust might be limiting power? But I know that nothing can be this cut and dry, and that all the inter workings of the 2 stroke must work as one.

RE the STA RPM. On the dyno the bike peaks right at 11750 in stock form, so I put that RPM in the sim for the calc. You think that HP number is low for that RPM? Take into account that this is indeed a 125, the data pack was made off a KTM150 pack I had already made. So thats why the STA says its for a 150.

-thanks

[wobbly]

Its not as simple as understanding the different dyno readings - the bottom line is that you will never see the crank power as simulated by EngMod on any dyno,
unless its connected to the ignition nut.
Or you can introduce a fudge factor ,like adjusting the inertia value so that you get a reading 10% high for example - if you really want to see the same results as the sim.
But you are right - we are dealing with small delta's on a dyno, to find what works and what doesnt, as long as your test procedure gives very repeatable results the actual number doesnt matter much.

Re the KTM , they all use VeeForce as stock I believe , so its very hard to get real improvements with these as you are severely limited in petal configuration , and making new stuffers is a nightmare.
Whereas the SKUSA CR125 reed block is easily able to be changed to give an extra 3 Hp simply by having differing petals top and bottom, and adding staggered backups to force symmetric inflow to the case..
If the late 125 is anything like the smaller engines , then there are big gains hiding in re configuring the A port hooks.
But of course the sim cannot replicate this type of scavenging improvement.
If you are using the engine in MX, then yes having it peak at 11750 will by definition mean that the pipe / porting is skewed toward making top end power - and that isnt what wins in short track dirt racing.
I would be looking at ways to pump up the upper mid that it must be lacking simply due to the peak rpm number.

[shnaggs]

Its not as simple as understanding the different dyno readings - the bottom line is that you will never see the crank power as simulated by EngMod on any dyno,
unless its connected to the ignition nut.
Or you can introduce a fudge factor ,like adjusting the inertia value so that you get a reading 10% high for example - if you really want to see the same results as the sim.
But you are right - we are dealing with small delta's on a dyno, to find what works and what doesnt, as long as your test procedure gives very repeatable results the actual number doesnt matter much.

Re the KTM , they all use VeeForce as stock I believe , so its very hard to get real improvements with these as you are severely limited in petal configuration , and making new stuffers is a nightmare.
Whereas the SKUSA CR125 reed block is easily able to be changed to give an extra 3 Hp simply by having differing petals top and bottom, and adding staggered backups to force symmetric inflow to the case..
If the late 125 is anything like the smaller engines , then there are big gains hiding in re configuring the A port hooks.
But of course the sim cannot replicate this type of scavenging improvement.
If you are using the engine in MX, then yes having it peak at 11750 will by definition mean that the pipe / porting is skewed toward making top end power - and that isnt what wins in short track dirt racing.
I would be looking at ways to pump up the upper mid that it must be lacking simply due to the peak rpm number.

Once again, thanks Wobbly!

The standard reed valve in these newer KTM's are their own version of a Vforce (w-block). They get the reeds from Carbontech, which is Boyesen's sister company which is made all in house I believe. I think Honda GP was using Carbontech reeds back in the day FWIW.

I agree that making the power band wider would be more desirable and useful. So, what you are saying is that the Exh port window area is not as crucial than the transfer port STA and the Blowdown STA, unless we are talking about an all out Kart/GP racer? So, if I bring the Exhaust STA value up to match the other STA's, I would most likely bump peak HP up but may loose some up the front side?

Thanks

[peewee]

carbontech petals seem good. had the same set in the methanol nitro bike since day one , last summer sometime. holding up fine i would say

[wobbly]

NO - adding area to the lower part of the Ex port ( below TPO ) will not increase power anywhere , so is not a " design " element I would use for kart/GP or anything for that matter.
As I said we have been trying for years to reduce the duct volume , at the port end area , as well as using my nozzle idea at the exit face end.
BUT , reducing the lower area further only works effectively IF you have already sufficient Blowdown , matched to the power you are looking for.

If you are not going to be going into pipe changes, then there is alot to be had tuning the powervalve and ignition curves.
So if you are really serious about this , then an Ignitech driving a cable connected servo on the PV is the go , and of course the ignition can then be tailored specifically to whatever mods you do.

[tdc211]

quote
But I just noticed that the STA numbers are generated at 11750 - so this must be used with a kart or road race type pipe , as no way would it be of any use on a MX track , peaking that high.


no Wob it peaks at 11800ish on pump with oem mx pipe, stock.
has pretty much no ign in it and 845ish pipe, 33ish/66ish, give or take ,29ish hp at 9000, (on more than one dyno) , isn't a slouch for mx

[TZ350]

338611 338612

A very stock Suzuki GP100 fitted with an un molested (but replated) NSR cylinder.

The only modification is a de stroked crank. It still has the original carburetor and no cylinder porting.

It will be interesting to see what it makes on the dyno tonight. Our guess is about 26 rwhp.

[F5 Dave]

And is there a spacer increasing volume and allowing 6 speed space?

[wobbly]

Looking at the power curves , I can see a comparison of two , one making 38 @ 11800 the other making 36 @ 11400.
But both have a big torque hole at 10500.
To me this would normally tell me the PV is fully open too soon , but then I look at the KTM STA sheet and see that the Aux ports are only 0.3mm below the main.
This tuning automatically kills the mid power big time at the expense of some top end and overev.
The 845 pipe is completely normal and has been used forever , so its the ports / PV / ignition that need looking at.
From my limited experience of actually doing an MX engine properly ( once , including data logging to see where and how often the mid power Vs overev is really used on track ) then keeping the
36 Hp curve but adding 4 Hp at 10500 would cut way faster lap times - been there done it, won the Nationals.
Its easy to do , as the 191 Ex duration means huge superposition is available to give a really flat torque curve with a ton of area under the Hp graph.

[TZ350]

Follow the link to read the whole story about Team ESE's GP/NSR110cc engine build. You will have to follow the links to see the whole post, pictures and related links.



338611 338612

A very stock Suzuki GP100 fitted with an un molested (but replated) NSR cylinder. The only modification is a de stroked crank with a RD400 rod and cut rotary valve 145/85. It still has the original carburetor and no cylinder or inlet porting.


And is there a spacer increasing volume and allowing 6 speed space?

No..... there are several versions of these GP/NSR110 engines but this particular engine is a very deliberate effort to see what can be achieved without doing very much.

This engine is as basic as can be and if it works, easily duplicated.

338616

Ok... now we know. Basic GP-NSR110 25rwhp. No porting, no trick parts, just a basic Suzuki GP100 bottom end fitted with a stock NSR250 cylinder and crappy NSR head and still running the stock Suzuki GP 24mm carburetor.

[tdc211]

Thanks for the explanation Wob. I understand that different dynos and whether wheel power or crank power is calculated will make a difference in the power reading.

I'm not too concerned with what my power number is, more just trying to wrap my head around this whole 'black magic' of 2 stroke tuning. See ive been messing about with different inlet valve configurations with no gain to be had. I was thinking

that maybe its pointless to be messing around with inlet configs when the exhaust might be limiting power? But I know that nothing can be this cut and dry, and that all the inter workings of the 2 stroke must work as one.

RE the STA RPM. On the dyno the bike peaks right at 11750 in stock form, so I put that RPM in the sim for the calc. You think that HP number is low for that RPM? Take into account that this is indeed a 125, the data pack was made off a KTM150 pack I had already made. So thats why the STA says its for a 150.

-thanks

Drop the head some with the oem pipe/silencer. . Shouldn't loose rpm. Pump gas. That means machining a new insert.

[dutchpower]

Looking at the power curves , I can see a comparison of two , one making 38 @ 11800 the other making 36 @ 11400.
But both have a big torque hole at 10500.
To me this would normally tell me the PV is fully open too soon , but then I look at the KTM STA sheet and see that the Aux ports are only 0.3mm below the main.
This tuning automatically kills the mid power big time at the expense of some top end and overev.
The 845 pipe is completely normal and has been used forever , so its the ports / PV / ignition that need looking at.
From my limited experience of actually doing an MX engine properly ( once , including data logging to see where and how often the mid power Vs overev is really used on track ) then keeping the
36 Hp curve but adding 4 Hp at 10500 would cut way faster lap times - been there done it, won the Nationals.
Its easy to do , as the 191 Ex duration means huge superposition is available to give a really flat torque curve with a ton of area under the Hp graph.
Here ign. curve KTM 125 '18

[TZ350]

Follow the link to read the whole story about Team ESE's GP/NSR110cc engine build. You will have to follow the links to see the whole post, pictures and related links.

338617 338618 338619

Ok... now we know. The basic GP-NSR110 build is 25rwhp. Basic because we wanted to make something that you did not need to be a 2T tuning expert to re produce.

No porting, no trick parts, just a basic Suzuki GP100 bottom end with a de stroked crank, cut rotary valve 145/85 and fitted with a stock NSR250 cylinder and crappy NSR head and still running the stock Suzuki GP 24mm carburetor.

[F5 Dave]

Looks like a great formula Rob. Clearly NF4 pipes aren't that common and some over rev would be nice but that's well useable with careful shifting.

[wax]

Tell me what you guys use when your spacing a cylinder up. Im looking for the right material . I was thinking plastic but what sort.

[wobbly]

So the KTM has an ignition curve with only one thing remotely "right ".
About 15* at peak power.
Throw in a bunch of advance below 11,000 and juggle that with the PV full open point and suddenly mid range power will appear from nowhere.
Then correct the idiotic Aux port stagger issue and a huge mid increase is available.
This may need the main lifting a little as part of the " fix "to increase the peak and overev capability , but for sure the torque hole will be gone.

[TZ350]

Tell me what you guys use when your spacing a cylinder up. Im looking for the right material . I was thinking plastic but what sort.Alloy plate.

[wax]

Thanks Im only going up 2mm and so it makes it a little tricky to make. I have a laser cutter so i can cut plastic if i want. I was looking for a good plastic to use

[husaberg]

Thanks Im only going up 2mm and so it makes it a little tricky to make. I have a laser cutter so i can cut plastic if i want. I was looking for a good plastic to use
1.6mm alloy spacer plus .4mm gasket with original gasket on other side.
I have one here i made with a drill and a dremill.
drill plenty of holes thus there is then no need to use snips that might bend the sheet.

[Frits Overmars]

Tell me what you guys use when your spacing a cylinder up. Im looking for the right material . I was thinking plastic but what sort.Base gaskets must be rigid; the cylinder ears will break off if not sufficiently supported. KTM, Kawasaki and Honda cylinder ears are notoriously vulnerable.
Using 1 mm of paper gaskets is already asking for trouble if you do not use a torque wrench.
If you're thinking of using 2 mm plastic here, you can save yourself some elbow grease by binning the cylinder right away.
338625

[tdc211]

Here ign. curve KTM 125 '18

Was that checked with a light?
My 16 ign curve nothing like that
150 cdi has more ign than a 125. at thats not even close to 15

[shnaggs]

NO - adding area to the lower part of the Ex port ( below TPO ) will not increase power anywhere , so is not a " design " element I would use for kart/GP or anything for that matter.
As I said we have been trying for years to reduce the duct volume , at the port end area , as well as using my nozzle idea at the exit face end.
BUT , reducing the lower area further only works effectively IF you have already sufficient Blowdown , matched to the power you are looking for.

If you are not going to be going into pipe changes, then there is alot to be had tuning the powervalve and ignition curves.
So if you are really serious about this , then an Ignitech driving a cable connected servo on the PV is the go , and of course the ignition can then be tailored specifically to whatever mods you do.

Sorry, I didnt mean take away from the lower portion of the port. I was going leave the main port alone, but maybe increase the Aux port width...they seem pretty small in comparison, but maybe they dont need to be that big.

But now after reading your other response, fudging the main port higher would possibly be a better solution. In this situation, would radiusing the upper portion of the port be beneficial, or just taking it up a bit would be better?

Will look into Ignitech, thanks!

[shnaggs]

Here ign. curve KTM 125 '18

Thanks for this!

[katinas]

Tell me what you guys use when your spacing a cylinder up. Im looking for the right material . I was thinking plastic but what sort.

Fiberglass plate with thin cooper layers, from electronic stuff. I use 1.5mm with " Wurth engine and housing sealing compound DP 300", for quick testing it works immediately, no leakage, no cracking. This year for testing I use four tube.
Like Frits write, stay away, if possible, from soft gasket as they always deform "ears" type cylinder. But if cylinder and head bolted to crankcase with same studs/bolts, maybe soft gasket is ok.

[peewee]

for cyl spacers, why not just use 6061 plate with klingersil homemade gaskets of appropriate thickness :niceone:. this method can be made with simple hand tools like drill, dremel and scissors. maybe plastic could work but I don't see what advantage there could be

about the timing light. is that a reasonable way to plot the ign curve of the cdi box ? ive found this one https://www.innova.com/en-US/Product/Detail/5568a?r=0.07858344023769935

[dutchpower]

Was that checked with a light?
My 16 ign curve nothing like that
150 cdi has more ign than a 125. at thats not even close to 15

Totaly different partno. '16 50439031000 '17 50439131000

[TZ350]

Looks like a great formula Rob. Clearly NF4 pipes aren't that common.

I go here for parts, Japanese TradeMe, RS125 pipes run about $300 NZD landed here in NZ. https://www.jauce.com/

Brought lots of different parts. Pipes, cylinders, wheels, NF4 fuel tank .....

[katinas]

And here I thought this site was allergic to piston port designs. I decided to take it to the limit with a divided intake. It takes a custom piston with a full skirt and a longer rod so the piston clears the crank web. I'm also considering Frits' 4 transfer design. It would fit on a stock crankcase with minor modifications. I'll need to finish modeling both versions to see if I missed anything.

Lohring Miller

337764 337765

Probably, intake duration can be little bit higher at deepest intake windows point, than at the frontal side. Would be interesting how engine respond with some angle on piston timing skirt.
Long time ago I had 75' IZ Planeta Sport ( Yamaha licensed copy) motorcycle with piston ported and C transfer 340 cc engine (add photo).

[F5 Dave]

I used to sandwich thin plate between two bits of thin plywood, clamp to cut without deforming plate.

Dremel with sanding drum will clean up without pulling it out of shape.

[wobbly]

Running a spacer plate with a gasket on each side I have had nothing but trouble with excessive crush .
I now use grey case glue between the case and the alloy spacer,then use a single gasket to set the squish.

Re the KTM Aux port shape - DONT widen the bottom of the triangle , all this does is increase the vertical short circuiting from the A port.
Widen the top and square it up.
But doing this ( as well as lifting the main to increase the stagger ) will increase the Blowdown STA - then you would need to work on the transfers to get the balance back.
In TM kart cylinders I regularly have to drop the cylinder alot to get the Aux and or one of the transfers in the right place - then grind all the other ports up to get everything correct.
Bastard of a job , but hey , thats what wins races.

[dutchpower]

Why engine don't react on changing ing.curve !!!!!! ( in engmod no problem )

[TZ350]

Running a spacer plate with a gasket on each side I have had nothing but trouble with excessive crush . I now use grey case glue between the case and the alloy spacer,then use a single gasket to set the squish.

Exactly what we do too. Seal the spacer plate to the cases with YamaBond. Then set the squish with a base gasket.

338636

[wobbly]

Ha Ha, very good question Dutch.
To me that KTM STA file tells it all , we have the very latest cylinder from a respected manufacturer and guess what - its a fuckup.
The Aux ports are WAY to high , the ignition curve is seriously useless ,and all the transfers open together. ( Yamaha have done the same with the 2018 YZ125 ).
Maybe all the good 2T engineers have retired .
So looking deeper I would bet the PV is all wrong , and as I already know ,the smaller engines have serious issues with the A port angles.
Thus - with everything you look at being off base , am I surprised changing the ignition curve does nothing - Na I would be surprised if it did work.

[TZ350]

And is there a spacer increasing volume and allowing 6 speed space?

Na .... not that engine, you are thinking of this engine.

338638

The one I have been experimenting with fuel injection on and which has all the bells and whistles.

338637

Currently I am setting it up with a multi toothed flywheel for a different fuel injection systems ECU. The flywheel/generator is from a direct injection Aprilia SR50. I hope the flywheel holds together at 14,000 rpm.

[peewee]

i thought of welding the spacer to the cyl but never got around to it. gluing it to the cases seems like it would work fine. at the moment im using a gasket on either side and it hasnt given me any trouble

[tdc211]

Totaly different partno. '16 50439031000 '17 50439131000


Hense the reason the older box likes head cut.
Didn't know that. Good info

[tdc211]

New ktm 105 cylinder i showed.
Low chart is normal fmf pipe most mx guys will buy
Cause it cheap and.hey fmf the best. Ya right .

One of my pipes red . Engine is box stock/28mm


Ktm redid tranfers/little less ex port volume
And dropped the subs to 91 and dropped the port timing
Doesn't have 3pv. Only one main.

Port Mods to come.

how much is less short circuiting/Aport and i imagine cfd designed tranfer tunnels and lower subs helped the midrange.
that's the question

[jasonu]

Thanks Im only going up 2mm and so it makes it a little tricky to make. I have a laser cutter so i can cut plastic if i want. I was looking for a good plastic to use

Will your laser not cut ali?

[TZ350]

338645

New tool to play with, super finishing then impinging with stealth coat. Basically super smooth and impregnated with slippery shit.

Developed by NASA for lube in outer space. Now used extensively in Formula 1 and NASCAR and Indy for greatly improved engine/gearbox reliability.

Boring I know, but this is also great for plastic dies and screw injectors too.

[jonny quest]

What's stealth coat?

[wobbly]

Dazz just did the transmission on Dennis 400 Superlight with the lube coating as well as a TM piston for me to dyno test the result.
He did the ring and small end pin as well.
Be interesting to see the result.

[shnaggs]

338645

New tool to play with, super finishing then impinging with stealth coat. Basically super smooth and impregnated with slippery shit.

Developed by NASA for lube in outer space. Now used extensively in Formula 1 and NASCAR and Indy for greatly improved engine/gearbox reliability.

Boring I know, but this is also great for plastic dies and screw injectors too.

What’s the details on this slippery shit?

[shnaggs]

Running a spacer plate with a gasket on each side I have had nothing but trouble with excessive crush .
I now use grey case glue between the case and the alloy spacer,then use a single gasket to set the squish.

Re the KTM Aux port shape - DONT widen the bottom of the triangle , all this does is increase the vertical short circuiting from the A port.
Widen the top and square it up.
But doing this ( as well as lifting the main to increase the stagger ) will increase the Blowdown STA - then you would need to work on the transfers to get the balance back.
In TM kart cylinders I regularly have to drop the cylinder alot to get the Aux and or one of the transfers in the right place - then grind all the other ports up to get everything correct.
Bastard of a job , but hey , thats what wins races.

Thanks Wobbly. I wouldn’t dream of taking more off the bottom aux, I’ve been learking around here too long to fall into that. Although I was surprised that you didn’t say I could widen the aux ports more, but I guess that would be too much and maybe not as beneficial, especially because of not having plugs for the wrist pin.

[wobbly]

The " slippery shit " is what Micro Blue use on bearing races after super polishing.
Developed by NASA , Dazz has the got the rights to apply this coating here in NZ - only just got the sign off on the process.

[TZ350]

Dazz just did the transmission on Dennis 400 Superlight with the lube coating as well as a TM piston for me to dyno test the result. He did the ring and small end pin as well. Be interesting to see the result.

Although the components were dry that pin just slipped right through the piston bosses real easy. Quite different to the way it was before it was treated.

I am very interested to see the dyno results.

[dutchpower]

Thanks Wobbly. I wouldn’t dream of taking more off the bottom aux, I’ve been learking around here too long to fall into that. Although I was surprised that you didn’t say I could widen the aux ports more, but I guess that would be too much and maybe not as beneficial, especially because of not having plugs for the wrist pin.

13.5 is the max

[Frits Overmars]

i thought of welding the spacer to the cyl but never got around to it. gluing it to the cases seems like it would work fine.It would, until you need to split the cases. I'd rather glue the spacer to the cylinder. But I'd never weld it.

[wax]

It would, until you need to split the cases. I'd rather glue the spacer to the cylinder. But I'd never weld it.

That could cause an issue

[Norman]

Regarding friction and ways to decrease, could this new two stroke oil be something? Based on the Triboron (TM) technology. Could it have a potential compared to well established racing oils and/or other possible friction modifiers? Friction measurements along with further statements are presented on the homepage (http://triboronproducts.com). Recommends to be mixed with half of what is used with conventional oils. It seems as if it has just come out on the market 2018. Statements from the two stroke oil data sheet:

"Triboron is a unique, patented technology for
reducing mechanical friction.
The Triboron Technology interacts with the
metal surfaces and forms a tribo-film layer
that reduces friction coefficient with up to
50% and protects mechanical parts from
wear.
In addition to sustainable fuel savings of up
to 10%, Triboron also reduces harmful
emissions of carbon monoxide CO and
hydrocarbonsHC with up to 25%.
Verified results in real-life and laboratory
tests. The Boron compounds and the
substances used in the production process
are harmless for nature."

[Norman]

Wrong, I can see that the Triboron two stroke oil has been out for years...

[SwePatrick]

Yes,.. that´s because triboron is 'snakeoil', many twostrokes seized.

[Dutch Fisher]

338645

New tool to play with, super finishing then impinging with stealth coat. Basically super smooth and impregnated with slippery shit.

Developed by NASA for lube in outer space. Now used extensively in Formula 1 and NASCAR and Indy for greatly improved engine/gearbox reliability.

Boring I know, but this is also great for plastic dies and screw injectors too.


Looking at your photo the coating looks very simliar to WS2

[wobbly]

Yes its Tungsten Disulphide.

Re the question I answered previously about seeing the Ex port STA seemingly too small.
Jan had incrementally reduced the area below TPO on the Aprilia cylinders to lower the duct volume and also reduce the A port short circuiting.
He was about to test a cylinder with the floor lifted way higher, but when 2T was killed by Honda in GP racing , Jan retired and the final tests were never completed.
This pic as the last tested iteration I believe.

[crbbt]

Thanks you for the CR250 piston link!

I had a race at Philip Island on the weekend. I was woefully average :laugh:


I have some questions regarding the toroid head design.

I've attached a questionable paint file.

anyway. with a 14mm spark plug. how wider do you make the flat area where the spark plug comes through? (the Y dimension in the paint file)

also I've been search the forum for 2 days straight, I know Wob has mentioned this before (but I cant find it). What is the distance you keep the spark plug from the top of the piston? (the X)

this accurate paint file has a squish band area of 50% the bore diameter and a squish clearance of 1mm (250mx)

[TZ350]

.
From Wobbly.
.
<iframe width="560" height="315" src="https://www.youtube.com/embed/Pdu8pVGwL78" frameborder="0" allow="autoplay; encrypted-media" allowfullscreen=""></iframe>

[wobbly]

Y = 18mm min , or the aluminium around the plug nose overheats.
X = I have been down to 3.5mm from the earth electrode face - there will be an optimum plug position Vs toroid depth , but I have not had the chance to test a
whole bunch of inserts with the same cc.

[husaberg]

NGK race plugs were originally designed to be about 1mm proud of the chamber,one reason there are no threads on the shell end.
This leads on to one reason that a toroidal chamber design works best.
I believe that plug position and indexing effects are reduced considerably by the quality of the CDI and the energy in the gap.
Using Ignitech and 0.2 Ohm primary Aprilia RS250 ( RGV) coils, I tested plug indexing and found no difference - but the fine wire R7376-10 plug made near on 2 Hp in 50 against a
Denso RS125 plug and a B10EGV.

TeeZee, use the new pack and go feature and send me your files - I will get bored over Xmas at the motherinlaws, and have a play on the laptop.

Y = 18mm min , or the aluminium around the plug nose overheats.
X = I have been down to 3.5mm from the earth electrode face - there will be an optimum plug position Vs toroid depth , but I have not had the chance to test a
whole bunch of inserts with the same cc.


"MSV is high at 25M/Sec", forget all that old shit - here is the go with squish.
In any race engine the squish height should be set at the minimum achievable,just shy of the piston tapping the head when overeved.
In a bucket where the norm is "only" 13000 there is no reason to have any more than 0.6mm.
The squish width based on MSV is a theoretical number of little relevance when we are running the piston in the powerband just short of hitting the head.
But with a parrallel squish ( ie curved same as piston dome rad - or a straight cut with minimal divergence) then in most cases we can use 40 to 45% squish area.
This generates MSV numbers in the high 30 M/Sec region.It has been stated in a few references that " high"squish velocity will bump up mid power and reduce the top end.
Yes, in a limited view of things it does.But now that we have digital programmable ignitions thats rubbish.
The high MSV increases turbulence in the end gases, this increases flame speed, and has the same effect as high com or too much advance.
Simply retard the timing and the rpm comes back, but you keep the power generated by better turbulence burning up more of the end gas trapped in the squish.

One point to remember is that the best radius on the squish corner into the bowl is no radius at all.A sharp corner with just with a rub of sandpaper to get rid of the ragged knife edge, works best.
And with any of the race type plugs we are using approx 1mm of unthreaded plug end should be protruding into the chamber.
The old B10EGV was originally designed to be used this way by NGK, but nowdays the trick plug is a R7376-10, this plug makes more power than any other tested with around +2 Hp better than an expensive Denso equivalent, here is the test i have shown before.

Here is a pic of one of several "form tools" I have used for years cutting chambers.
Now there are plenty around I always use CNC to generate a toroid insert, based on a CAD construction of the chamber, as its simply too hard to get a good shape ( and is a prick to measure properly) when doing it by hand.


You should cut the plug surface such that the unthreaded end of the plug body protrudes 0.5mm into chamber.
With a 10 range plug, then the vol to top of the plug hole is exactly 2.2cc bigger than the chamber.
I use ATF in a burrette, no grease on the bore as you want to measure the above ring crevice vol as well.
Find tdc, then drop the piston a small amount - fill the vol to 1/2 way up the threads, move the piston up/down, till fluid sits the highest,then fill to top.
Leave the burrette sitting for 5 mins as the fluid left on the glass walls slowly runs down.
While this is happening you can take off the head and clean things out.
............

[TZ350]

I've been search the forum for 2 days straight, I know Wob has mentioned this before (but I cant find it). What is the distance you keep the spark plug from the top of the piston? (the X)

Here you are, I used the Google "site:" term. ie; " plug to piston distance site:https://www.kiwibiker.co.nz/forums/showthread.php/86554-ESE-s-works-engine-tuner "


To do a toroid properly you need to drop the plug tip to approx 6mm from the piston crown.

[tdc211]

I can't help but notice this line in the cylinder
Maybe my eyes are deceiving me.
So hard to tell from a pic.
My free hand red line isnt perfect.

[peewee]

why guess. theres already some vinamold photos around here some where of the rsa transfer passages that show pretty clear the rearward angle

[wobbly]

You are ignoring the huge hook on the A port front wall.The flow angle points right in front of the boost port.

[dutchpower]

Scan rsw/rsa aprilia

[husaberg]

...../..
You are ignoring the huge hook on the A port front wall.The flow angle points right in front of the boost port.


Scan rsw/rsa aprilia
338670

[crbbt]

Thank you for your responses!

I drew (solid edge drew) a line from the edge of the squish band to the center of the combustion chamber. tangential to the squish radius

that distance was approximately 2.5mm above the crown of the piston.