ESE's works engine tuner

[jonny quest]

We tried various flat, and radiused pistons, but the original ROTAX dome always gave the best results.
With flat pistons the flow detaches which gives less piston cooling.

Did you try the hybrid Yamaha style? Flat top with chamfered edge?

[jamathi]

Yes, of course....not better!

[jamathi]

Biaggi's cylinders were named APB, originally designed by AVL in Austria
As designed they were useless, but they were developed very well by my colleagues at Aprilia.
Only Biaggi used them, their development was stopped in the beginning of 1998, when the APC became better.
The APD was a 7-port cylinder which proved useless.
It had been developed using a Jante-type flow bench, made in Brno, Czechia.

[jamathi]

Quite different looking in cylinder detail from the Biagi 250
330179

whoops wrong pic thats the 500.
https://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=314852&d=1439765447

So the pic on the right is the Biagi cylinders made elsewhere?

These is the cylinders i normally associate with an early Aprilia
https://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=330165&d=1492314330https://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=314851&d=1439765439
I have an DEA almost copy of it

These are APC cylinders, copied by many kart engine manufacturers.....

[jamathi]

Does it have a common crankcase for both cylinders?

No, would not have made any sense.....
See the picture.
On the right the 250 with APB cylinders.
A longer stroke was tried without success.
And during one test the piston pin came out of the carburetor....

[husaberg]

The 258 drawing is only 23 kB and very difficult to read?

See how this goes.
330196330199
I don't have access to any decent picture programes at the moment.
I can't find the source for the origional on the net but it appears to be from a official Rotax parts list.

[seattle smitty]

Mr. Thiel, over the course of your career, did you ever have any contact with the outboard hydroplane racing community in Europe, or ever have any personal interest in that sport? Not to dismiss motorcycles, karts, sleds, ATVs, etc, but outboard racing (the classes in Europe include 125cc (singles-only), 175cc, 250cc, and 500cc)(in the USA we have those plus 700cc and 1100cc) has some attributes which might appeal to an engine man:

First, since you have a whole lake or river full of (relatively cold) water available, designing provisions for cooling is considerably simplified.

Second, the engine burns methanol, which has several advantages over gasoline which I don't need to describe for you (and in the USA we're free to go beyond methanol to any liquid fuel, though few do so). One real advantage of this at the races is that we don't have our fuel inspected and approved by anyone!

Third, there are no problems of cornering traction as with motorcycles that require an engine designer to compromise his designs; with a propeller hooked up to the lake, a driver can use all the power the engine designer can provide.

Fourth, the racing outboard engine designer is barely constrained by such factors, found in motorcycling, as cornering clearance, fitting the engine into the frame, joining the engine to the transmission, etc.. in recent outboard racing practice with multi-cylinder engines, opposed-twins (and fours) using a common crankcase have been popular, being lightweight, relatively simple, with good balance and reduced rocking moment.

Fifth, as for pipes, an advantage in fabrication time when testing expansion chambers is that they are easy to build, being straight-line downstream of what our Kiwi buddies call "the spigot."

Finally, with those straight-line pipes hung out back of the engine and supported by brackets, we are able to add an extra element of "tunability" by making the pipes slide in and out over a range of about 10cm. For temporariy lowering the powerband even further, as when getting the boat on-plane, with our lake-full of water we can also spray a little water into the pipe, slowing the acoustic waves. These two features help us live without the necessity of a transmission.

I would think, given your toils over the decades, you would regard our situation as almost laughably easy by comparison! Anyway, most eager to hear your comments.

(EDIT) Three fellows you might have encountered, previously involved in GP motorcycling in the 2-stroke years and more recently building outboards, are Giuseppe Rossi, Carlo Verona, and Holger Arens, and also the late Dieter Konig.

[jamathi]

No, I never had anything to do with outboard engines.

[trevor amos]

Hello Jan, let me first say how much all viewers of this site are enjoying your anecdotes from the many years your racing past.
I notice from details released by Frits that the Aprilia piston crown had a radius of 190mm, giving a crown height of 1.9mm. Most other 125 race engines use a piston crown height with a smaller radius and therefore a taller crown height. Are there specific reasons for using this lower crown height, if so could you perhaps explain the reasoning behind this strategy?
Regards, Trevor

[jamathi]

No specific reason at al, it just went well as it was designed many years ago.
Probably at ROTAX by someone who had no idea why he did it!

[husaberg]

No specific reason at al, it just went well!

Jan, Frits has mentioned the results you obtained from a Reed valve derbi before you started on the Derbi engine with the rear disk that became the RSA.
Do you recall What changes you made.


A technical explanation? Nah, too much to do today. But since you were kind enough to post that picture of your sex six sisters, I will show some curves of my own.
When Jan Thiel went to Derbi to design the bike we now know as the Aprilia RSA125, he encountered the 125 cc reed valve Derbi ridden by Lorenzo the previous season. Jan played around with the reed valver as well, because he wanted to find out the differences between reed valve and disk valve power. He managed to extract 2 HP more from the reed valver than anyone else had ever done before (never mind the fairy tales of reed valve 125s producing over 50 HP; those Horses must have been Shetland ponies, probably measured at the piston ring).
My graph shows the power curve for the Aprilia RSA, the Aprilia RSW and that best-ever reed valve Derbi. It's not quite in the same league as the rotaries, hmm?

EDIT: Shame on me; I discovered that I posted a wrong graph (and I do not have the correct one at hand here in Holland). Power curve DERBILOR shows the reed valve Derbi as Lorenzo rode it. After Jan finished playing with it, it had 49 HP. Still, the best-ever disk valver produced 10 % more power than the best-ever reed valver.
321334

I looked it up Chris: you joined the KiwiBiker forum three months before I did, so you may already have seen everything I could contribute, including these powercurves from the Aprilia RSW, the RSA and the reed-valve Derbi ridden by Jorge Lorenzo in 2004, I think it was.
Honda had already abandoned development of their 125 cc racers but Derbi-tuner Harald Bartol had carried on with his Honda-clones (the Derbi cylinders and pipes were exact Honda-copies). Bartols best result was 47,6 hp.
When Jan Thiel joined Derbi, he played a little with Bartol's inheritance and he managed to extract 49 hp out of the reed-valver before concentrating again on his own disc-valve engine.

[jamathi]

Mainly working on the crankcase.
Improved water cooling passages, which were far too small
And some work on the inlet with good effect.
We made some cylinders with a different exhaust duct, with auxiliary's.
They were cast, machined, and plated.
Then Derbi was closed and I had to go back to Aprilia without trying them....
Still sorry!
The central bridges in the exhaust keeped cracking.
And I really came to hate reed valves!!!!
Being used to rotary valves that never gave any trouble......

[husaberg]

Mainly working on the crankcase.
Improved water cooling passages, which were far too small
And some work on the inlet with good effect.
We made some cylinders with a different exhaust duct, with auxiliary's.
They were cast, machined, and plated.
Then Derbi was closed and I had to go back to Aprilia without trying them....
Still sorry!
The central bridges in the exhaust keeped cracking.
And I really came to hate reed valves!!!!
Being used to rotary valves that never gave any trouble......
Thanks Jan
Speaking of rotary valves did the CF ones at Aprilia give any trouble or have any measurable gains. From the material rather than the shape.
I have seen the pimple finish casings which i asume is for retaining oil fuel for lubrication and decreaded friction surface.
330228330229330230
Were they coated with anything slipery?

[jamathi]

We never had any trouble with the rotary valve!
With the reed valve we had trouble every day....

[shnaggs]

We never had any trouble with the rotary valve!
With the reed valve we had trouble every day....

When you say you had trouble with the reed valve, do you mean you had trouble with it repeating on the dyno? Or trouble trying to get power out of it?

[RomeuPT]

Hello.

Long time since I posted on this thread. Being watching this weekly has it one of the best 2 stroke threads ever, keep going guys :)

There was an engine, that had several people making stuff for it here in Portugal, and the small end top part of the rod blown up in the first miles of running in (claimed by the owner). He also says that there wasnt any strange noise on the engine before the "tic-tack and blow". Squish clearance 1.2mm, with combustion chamber designed by me. Around 12:1 compression

I would say that is con rod fault 99% sure, but now each one blames each other works has the fault :/.

The rod is a wossner and the engine is a DT125 with athena big bore, 54mm stroke cranck etc

Cylinder/piston/cases, reeds etc goes to trash.

pics attached, what do you experts think

Cheers

[Norman]

Also to me that shiny circled area looks suspicious, and I believe there could be a bonding fault or a large pore in the casting/forging from the manufacturing. This must be detrimental in that area. Possibly it could even have been positioned just under the surface, not possible to detect without x-ray or ultrasound detection. There is a good chance that any metallurgist/lab with a microscope can check the cracked surfaces and conclude the root cause.

[tjbw]

I was thinking the circled area might contain a fatigue crack surface, in which case the matching part would have an identical pattern.

[Norman]

I was thinking the circled area might contain a fatigue crack surface, in which case the matching part would have an identical pattern.

Yes, hmm..you are right, could be that too. When the crack has propagated from a point (possibly a surface defect causing crack initiation) and by each cycle you get an additional half circle pattern (striation) that shape a large crack, and eventually it is large enough to cause a sudden failure/rupture. The crack propagated surface and the later ruptured surface will have different appearance, which you would look for in a microscope. Could be that you in worst case need a scanning electron microscope to sort things out.

[Grumph]

I'd do a simple hardness test on the surviving rod pieces. My suspicions lean toward faulty heat treatment leaving the small end brittle.

Any pic of the small end bearing - or what's left of it ?

[ken seeber]

My suspicions lean toward faulty heat treatment leaving the small end brittle.



Agreed. And for the actual eye of the rod to split as well is unusual. I've seen a few kart rods broken, but almost always thru the shank, not the eyes.

[Flettner]

Agreed. And for the actual eye of the rod to split as well is unusual. I've seen a few kart rods broken, but almost always thru the shank, not the eyes.

+1 , not tempered properly, or not masked properly in hardening.

[Grumph]

Agreed. And for the actual eye of the rod to split as well is unusual. I've seen a few kart rods broken, but almost always thru the shank, not the eyes.

Yeah, I've broken as much or more stuff than most - but never seen a rod break out the small end.
Since a good friend got a magnaflux setup, I've broken a lot less, LOL

[husaberg]

Hello.

Squish clearance 1.2mm, with combustion chamber designed by me. Around 12:1 compression
Cheers


For squish to be effective it needs to be up close and personal
They need to just kiss and end up just short of making intimate contact
1.2mm clearance is not squish, its barely holding hands.:bleh:

[jamathi]

When you say you had trouble with the reed valve, do you mean you had trouble with it repeating on the dyno? Or trouble trying to get power out of it?

Of course the reed valve is a big obstruction for inlet flow.....
While a rotary valve is not!
And when dyno testing the reeds keep breaking, costs you half of your time.....
The rubber detaches itself from the reed case after some time.
I really HATED it!!!!

[tjbw]

Here's a broken small end, with fatigue crack:

http://products.asminternational.org/fach/data/fullDisplay.do?database=faco&record=729&search=

No special equipment required to see the fatigue surface.

[speedpro]

I looked at that broken motor and "my" immediate thought was that it had the tits revved off it, speaking from experience with such disasters. The broken little end need not have been due to any sort of flaw. I've smashed a 4-stroke rod in such a way on a roller crank type engine and I've completely smashed the little end on one 2-stroke, not to mention giving the rod 2 90-degree bends and a twist, and broken chunks off a couple of other little ends.

[TZ350]

330245

... the small end top part of the rod blown up in the first miles of running in (claimed by the owner). He also says that there wasn't any strange noise on the engine before the "tic-tack and blow".

After all your work, I am sorry to see the rod failure. I had something similar with a cast piston which fell apart when it was revved well past its normal range. The only warning was a little tinkle in the expansion chamber which I assume was bits of piston, I got the clutch in just before the engine beat itself to death.

The end of my rod was missing too and the pin was split lengthwise into several bits, all the bottom of the piston below the rings was missing and funnily enough the piston crown was still in the bore and from the top it looked as if nothing was wrong.


330244

... an engine, that had several people making stuff for it here in Portugal,

I am very interested in the head shape, it is hard to tell but are the sides straight bath tub like or curved like a toroidal? I ask because one I made recently looks similar and I would be interested in your impressions about yours.

[RomeuPT]

Thanks all of you for replys.


After all your work, I am sorry to see the rod failure. I had something similar with a cast piston which fell apart when it was revved well past its normal range. The only warning was a little tinkle in the expansion chamber which I assume was bits of piston, I got the clutch in just before the engine beat itself to death.

The end of my rod was missing too and the pin was split lengthwise into several bits, all the bottom of the piston below the rings was missing and funnily enough the piston crown was still in the bore and from the top it looked as if nothing was wrong.



I am very interested in the head shape, it is hard to tell but are the sides straight bath tub like or curved like a toroidal? I ask because one I made recently looks similar and I would be interested in your impressions about yours.

Head shape has no logic, its just the athena piston is 66 and many dt users just fit it with a standard head (56mm) so the flat part is to make sure even when the user is stupid it will not be a big problem.

Cheers

[breezy]

Transfer ducts.

Many transfer ducts with small differences were tried.
We found more power by enlarging the A-port in the direction of the exhaust.
Only the lower half, but it was important to give the A-duct an inclination away from the exhaust!
The ducts were very conical, the smallest point being the port.
In and outside walls of the ducts had a constant radius from top to bottom.
The flow remained attached to the inside radius and so cooled the piston and eliminated detonation.
Flow bench testing and the Jante type testing proved useless for power improvement.
Giving the rear side of the B-duct an inclination versus the middle of the cylinder gave a big improvemet

Jan, how were you able to know when the flow was attaching or not to the transfer walls?

[marsheng]

Do you remember the difference between both of the A-port variations from the picture? Which was better, version A or version B?
330106


Have I missed the answer to this ?

Also what were the timings of the ports and roof angles.

Thanks Wallace.

[Frits Overmars]

Have I missed the answer to this ? Yes you have.
Version A was the best.

Also what were the timings of the ports and roof angles.The drawing shown by Jan in post #25655 showed an elder type RSW cylinder. Here are the RSA values.
A-ports timing 130°, roof angle 25°
B-ports timing 132°, roof angle 10°
C-port timing 132°, roof angle 50°

[Frits Overmars]

Some wishful thinking:
330290

And some miraculous saving:
https://www.facebook.com/MotoGP/videos/10155598630555769/

[Peter1962]

Some wishful thinking:
330290


That is a nice concept of a KTM 2 stroke roadbike, based on the 300 cc enduro engine ? Probably the 2018 version with injection in the transfers ?

[jfn2]

Frits:
It looks like the guy fell asleep! Mesmerized maybe?

[SwePatrick]

The crankshaft my friend made for me:
https://scontent-arn2-1.xx.fbcdn.net/v/t31.0-8/18121215_10154874263689475_3753958032529664716_o.j pg?oh=58ce616deed73848e0fae99637cfcaba&oe=59820765

Full of dirty fingerprints *lol*

I´m hotlinking to facebook, can everybody see it?
tried to upload to forum, but there was an error.

[TZ350]

Page ......... 1720




Here's a product called Composimold being used by a Thomas H who appears to cruise this forum, if not only the ESE thread. It's far more expensive though at $66NZD + $30 shipping for 20oz of the stuff -_-

http://bucketracing.blogspot.co.nz/2017/01/port-molds-with-composimold.html

https://4.bp.blogspot.com/-xXoJKt0qIGw/WI5B3c9h3zI/AAAAAAAAAfs/IW5qOcnbqg0ULUYPwarY6ArSSr65ZPM5wCLcB/s400/Port_Molds3.jpg


OK you blokes chasing Vinamould, here’s the stuff we use. For you kiwi types, it’s “cheap as chups” (:laugh::laugh::laugh::laugh:) around $100 for the 3 kg.

330857330858330859

Looked up your local contact:

Barnes NZ - Henderson, Auckland
B92-94 Railside Ave, Henderson, 0612 Auckland.
T: 09 973 1816
E: glen@barnesnz.co.nz


Isn’t anyone casting anything? It’s getting quiet here.:crybaby:


Google.co.uk came up with:

Vinamold - Best Value - - Direct from the manufacturer‎ (http://www.extruflexonline.co.uk/vinamold.html)

Ad<cite class="_WGk">www.extruflexonline.co.uk/vinamold</cite>‎
Large UK Vinamold Stocks, 24 Hr Delivery

4 hardness types?

I thought Vinamold was american.


ATAC in general works much lower down the powerband than a powervalve does, and cannot be gradually reduced in its effect.
It works very well to reduce the effect of the pipes return pulse being way too early at lower rpm, but this effect kills the power badly as soon
as the pipe efficiency starts to rise - thus the valve connecting the Helmholtz chamber to the pipe must be switched instantly at a specific rpm.
In a 125 race engine the ATAC would be off at around 8000 rpm, where as the PV may not be closed fully to within 1000 rpm of peak power.


Here comes the steamroller...

https://youtu.be/W0HVnlTbfVQ



Just a walk in the park ..... 324706

For the benefit of those struggling with that attatchment. 3 classes run together, Scott second over the line behind a good KR150 well ridden, and in front of a bunch of development class bikes which was led by an Aprilia 125....Next bucket a wee way back.

Damp conditions....

Interesting how close the best lap times are.


we should turn are buckets into these . go pinky

https://www.youtube.com/watch?v=y-gyBmAr2i0


takeing on the new master

https://youtu.be/kfuTSGSw1Ls i need to get fit lol


https://youtu.be/hxMFqtTYjr4


race 1 from weekend

https://youtu.be/VjCtIDTSKRY (https://youtu.be/VjCtIDTSKRY)


race one tepuke , fatboy pulls the plug and finsh his body of lol

https://youtu.be/NFRyZpzsyY8 (https://youtu.be/NFRyZpzsyY8)


race 2 , regans chain comes off but alex has the ride of his life and takes his first north island win

https://youtu.be/dBDWdq9k6Nc


jason on pinky starting at the back at hamton

https://www.youtube.com/watch?v=1lh3awTX7Go&feature=youtu.be


The last race was the best to watch, sorry about the shaky camera, need a better one. Rained just before the start.

https://youtu.be/PlO4_uHaq00


Where the pic is click on the link where it says load in 3d viewer and play with your mouse

330482330481


I made a few cuts in the model and copy paste pictures on the inside of the RSW cylinder from GrabCad. Very interesting!


There are Nsr125, NSR250 and RS125 sectioned cylinders and 3d models to compare them to on the net.

http://thetrxproject.blogspot.co.nz/2013/04/


330489330490330491330492330493330494

[TZ350]

The crankshaft my friend made for me.

That is a great piece of work, I like it.

[jamathi]

Jan, how were you able to know when the flow was attaching or not to the transfer walls?

By looking at the piston.

[jamathi]

Yes you have.
The drawing shown by Jan in post #25655 showed an elder type RSW cylinder. Here are the RSA values.
A-ports timing 130°, roof angle 25°
B-ports timing 132°, roof angle 10°
C-port timing 132°, roof angle 50°

RSW and RSA ducts were the same.
Roof angles did not change since 1995
The RSA cylinder had improved cooling.

[peewee]

i finally installed the pressure release valve. i should have done this very first instead of waiting to the end :facepalm:. i hope now it turns over easy without worry of damaging the kickstart gears. i thought about taking more material from the chamber to lower the com ratio but its already pretty thin so ill probly leave it be. if need be, i might get another head and weld a spacer to the sealing face so i wont have to cut into the chamber so far.

hi jan i was wondering if you saw any increase in revs when the rsa125 compression ratio dropped from 19.5 to 16:1 ? i have 19.5 also and worry it might hurt my revs

[jamathi]

i finally installed the pressure release valve. i should have done this very first instead of waiting to the end :facepalm:. i hope now it turns over easy without worry of damaging the kickstart gears. i thought about taking more material from the chamber to lower the com ratio but its already pretty thin so ill probly leave it be. if need be, i might get another head and weld a spacer to the sealing face so i wont have to cut into the chamber so far.

hi jan i was wondering if you saw any increase in revs when the rsa125 compression ratio dropped from 19.5 to 16:1 ? i have 19.5 also and worry it might hurt my revs

Yes, we got 500 rpm more!

[Tim Ey]

Jan, did you ever thought about using bearings with steel cover discs instead of a labyrinth seal?
(6204-z-c3 would be an example)
so you may use two bearings right next to each other without the need of any extra parts.

the question is where to place the covered side.
1. covers at the crank webs with an oil feeding hole between them
pro: crankcase volume does not differ
con: might get full of oil

2. covers facing each other, feeding hole in the middle
con: probably not enough oil supply

3. using only one closed bearing with feeding hole in the middle
pro: more vented bearings than 1.
con: crankcase volume of one gets higher than the other

Nobody got experience on that topic? :-)


i have 19.5 also and worry it might hurt my revs
Are you talking about your 500 (?) cc KTM engine?
Whilst using 19.5:1 in it I would guess you be losing the lower end bearing before losing any revs :-O

[breezy]

By looking at the piston.

ok, so this would show that the the flow was attaching to the inside wall of the transfer port and keeping the edge of the piston clean to prove?:. what about the outside wall of the transfer port? or does this prove this too.?

[peewee]

Nobody got experience on that topic? :-)


Are you talking about your 500 (?) cc KTM engine?
Whilst using 19.5:1 in it I would guess you be losing the lower end bearing before losing any revs :-O

im sure the bearing wont be happy but I don't think it will fail immediately. from the beginning I should of gave more thought to everything :facepalm:. I may be learning the hard way but atleast im learning :laugh:. what I really would like is about 5cc more, so ill think of the easiest way to do that. eventually ill get it sorted out.

[speedpro]

ok, so this would show that the the flow was attaching to the inside wall of the transfer port and keeping the edge of the piston clean to prove?:. what about the outside wall of the transfer port? or does this prove this too.?

getting any moving fluid/object to the outside of a curve is never a problem, centrifugal force.

[oldjohnno]

Jan, did you ever thought about using bearings with steel cover discs instead of a labyrinth seal?
(6204-z-c3 would be an example)
so you may use two bearings right next to each other without the need of any extra parts.

the question is where to place the covered side.
1. covers at the crank webs with an oil feeding hole between them
pro: crankcase volume does not differ
con: might get full of oil


2. covers facing each other, feeding hole in the middle
con: probably not enough oil supply

3. using only one closed bearing with feeding hole in the middle
pro: more vented bearings than 1.
con: crankcase volume of one gets higher than the other

The seals or shields used on closed bearings are primarily designed to keep the grease in and the dirt out; they aren't able to operate to provide positive sealing at any significant pressure.

[Tim Ey]

The seals or shields used on closed bearings are primarily designed to keep the grease in and the dirt out; they aren't able to operate to provide positive sealing at any significant pressure.

My RS250 labyrinth seal got an inner diameter 0,5mm bigger than the piece of crank where it is seated. The closed bearings have way less of a gap than that.

[Grumph]

My RS250 labyrinth seal got an inner diameter 0,5mm bigger than the piece of crank where it is seated. The closed bearings have way less of a gap than that.

I would suspect that when running, a rolling element bearing would act as a labyrinth seal - but as to whether it would seal well enough to get a motor started, I couldn't guess.

[oldjohnno]

My RS250 labyrinth seal got an inner diameter 0,5mm bigger than the piece of crank where it is seated. The closed bearings have way less of a gap than that.

Uh yeah, but it's a labyrinth, not a single lip.

[husaberg]

Yes, we got 500 rpm more!

Jan i seen this pic of the RSA250 today
The inlet seems a little longer than the RSW or RSV
330409
330411330410

[marsheng]

Yes you have.
The drawing shown by Jan in post #25655 showed an elder type RSW cylinder.
Thanks very much. Casting a new barrel is on my list.

Can you cast a barrel around a cast iron sleeve or do you have to cast, bore and then insert new sleeve afterwards ?

[Frits Overmars]

Can you cast a barrel around a cast iron sleeve?One can, and one has; it's called the Alfin technique.

[jonny quest]

RS250 cranks, I have one here to rebuild. Where can I order the parts to rebuild?

[WilDun]

One can, and one has; it's called the Alfin technique.

Wasn't that process used a lot by Kawasaki back in the sixties and seventies? - not so sure that they were the first to use it though - that honour might have gone to Velocette (by my fast fading memory).

UPDATE: Sorry, seems it was invented by the Fairchild Aircraft Company in America.

[Nath88]

I took the injected YZ for a decent ride on the weekend, about 150km of mountain roads. Averaged 4.7L/100km! Down from 7 on the carb. I'm still figuring out what air fuel ratios it likes, gradually leaning it out based on how thick the blue cloud is, so there's more fuel economy to come. Will need some dyno time to find the best full throttle mixtures through the range. I haven't experimented at all with injection timing, currently injection starts at 135°, Injection duration at idle is about 20°. I could probably delay the injection at light loads for less loss to the exhaust, potentially more gains to come in this area.

Biggest development lately has been incorporating the exhaust pressure feedback over a range rather than a switching point, and at all engine speeds rather than just on the pipe. I originally had the fuelling set to double when exhaust pressure reached 1.02x atmospheric pressure, however I found that at 100km/h cruise (~7% throttle, 6500rpm) exhaust pressure was only 1.01, so it didn't trigger the additional fuelling and the mixture went extremely lean. So now the additional fuel is added progressively as exhaust pressure ranges from 0.98 to 1.04, which is where the pressure fluctuates at idle and light throttle. The result is a very carb-like analog feel, it idles and cruises more smoothly, and the revs don't dip when returning to idle. The highway cruise problem is solved, it will now tolerate small throttle openings without four-stroking, it sounds a bit strange cruising smoothly from 80km/h up. Very happy with how its going, still needs tuning on the high rpm transition, doesn't quite feel like a 4 stroke yet.

If you're in Brisbane and want to test ride it, PM me.

[F5 Dave]

Don't be a cheaparse Wallace get it plated, the benefits are well covered in this thread. Obviously the Bucket foundry thread has mondo info to absorb.

[2T Institute]

RS250 cranks, I have one here to rebuild. Where can I order the parts to rebuild?

Honda or Aprilia?

[marsheng]

Don't be a cheaparse Wallace get it plated, the benefits are well covered in this thread. Obviously the Bucket foundry thread has mondo info to absorb.


I think making a sleeve with time and materials is probably more expensive than plating. The main plus of this is, I can CNC the sleeve with all the right port sizes and angles. The 2 other advantages are, I can change the port timing later on and I can use all those new +.5 +1.0 +1.5 pistons I have.


Still investigating it all.

Cheers Wallace.

[Grumph]

I think making a sleeve with time and materials is probably more expensive than plating. The main plus of this is, I can CNC the sleeve with all the right port sizes and angles. The 2 other advantages are, I can change the port timing later on and I can use all those new +.5 +1.0 +1.5 pistons I have.


Still investigating it all.

Cheers Wallace.

If you decide to cast and plate, check with NZ Cylinders as to what single cylinder top anode plates they already have. If they don't have what you want, making one is an expensive part of the plating job.

[jonny quest]

Honda or Aprilia?

Hondas Road Race only version. Have to check year, but it's definitely one of the last versions made. Looking for rod kits, and outside and center bearings/seal.

[husaberg]

Hondas Road Race only version. Have to check year, but it's definitely one of the last versions made. Looking for rod kits, and outside and center bearings/seal.

http://www.risingsuncycles.com/bikespecific/rs125/rs125pa.htm

http://www.samarin.net/?productos
http://www.samarin.net/?productos=&accion=buscar&idtipo=5&idmarca=8&a=&c=&f=&jaula_piston=&b=&d=&l=&jaula_ciguenal=&Submit=BUSCAR&paginas=2&&id=1379

[Frits Overmars]

... making a sleeve... I can use all those new +.5 +1.0 +1.5 pistons I have.Isn't that a bit like starting to smoke because you found a packet of cigarettes?

[F5 Dave]

I think making a sleeve with time and materials is probably more expensive than plating. The main plus of this is, I can CNC the sleeve with all the right port sizes and angles. The 2 other advantages are, I can change the port timing later on and I can use all those new +.5 +1.0 +1.5 pistons I have.


Still investigating it all.

Cheers Wallace.
If it has to be a sleeve make it ally and plate it. But a 250 is huge so easy to tickle the ports. Try it on a 40mm bore.

[2T Institute]

Hondas Road Race only version. Have to check year, but it's definitely one of the last versions made. Looking for rod kits, and outside and center bearings/seal.
Centre bearing/seal is available I will have to post a pic later. Will depend on if you have 24 or 25mm crank pins sounds like NX5 or NXA(NX5 has single side swingarm NXA dual) which might have 25mm crank pins

[ken seeber]

Isn't that a bit like starting to smoke because you found a packet of cigarettes?

Frits, I guess the inverse of that is when a teenage guy starts chasing women cos he found he had a penis. :drool:

Wallace, if I had the choice of cylinder bore options (presuming you’re going to cast the cylinder and it looks like you have the gear), to me it would be:

1. Plate the bore. Heat transfer, durability and probably less total cost (time & $s) in the end.
2. Shrunk in liner. Ports can be accurately machined in with a dividing head. Any upsweep can be simply carefully filed in after the basic port is in place, ok at least for only a couple. However it does give you the ability to remove the liner and mod the ports a bit.
3. Cast in liner. Having seen the cast-in liner fall out after a cylinder (eg 70 – 90s Jap technology) is cut in half, I would never consider it. Interface was covered with gaps, coldshuts, black shit all around the exh port etc = crap heat transfer.

[husaberg]

3. Cast in liner. Having seen the cast-in liner fall out after a cylinder (eg 70 – 90s Jap technology) is cut in half, I would never consider it. Interface was covered with gaps, coldshuts, black shit all around the exh port etc = crap heat transfer.

Thats why Yamaha used to use corragated sleeves, that plus increased surface area, from memory the sleves are coated with something like zinc or some aluminum based oxide coating for better heat transfer prior to casting the cylinder arround it.
But yes coated one piece casting simpler and much better.

[Frits Overmars]

1. Plate the bore. Heat transfer, durability and probably less total cost (time & $s) in the end.
2. Shrunk in liner. Ports can be accurately machined in with a dividing head. Any upsweep can be simply carefully filed in after the basic port is in place, ok at least for only a couple. However it does give you the ability to remove the liner and mod the ports a bit.
3. Cast in liner.
Option #1 is best. But if for some reason it is out of the question, then take a look at option #4.
4: Pressed-in conical light-alloy plated liner. It was the method developed by Jan Thiel before he switched to option # 1.
Option #4 has all the advantages of option #2, plus the liner can be easily removed and refitted using a very slight press fit, without applying heat.
Jan used a morse cone angle (3° included angle if memory serves) on the cylinder bore inside and the sleeve's outside.
Of course you need not use a plated light-alloy liner; you can do the same thing with a cast-iron liner.

[marsheng]

Isn't that a bit like starting to smoke because you found a packet of cigarettes?

With a 2 stroke, I already smoke. Oh but what a nice smell.

[JanBros]

Option #1 is best. But if for some reason it is out of the question, then take a look at option #4.
4: Pressed-in conical light-alloy plated liner. It was the method developed by Jan Thiel before he switched to option # 1.
Option #4 has all the advantages of option #2, plus the liner can be easily removed and refitted using a very slight press fit, without applying heat.
Jan used a morse cone angle (3° included angle if memory serves) on the cylinder bore inside and the sleeve's outside.
Of course you need not use a plated light-alloy liner; you can do the same thing with a cast-iron liner.

For my honda Sky MX moped, I refuse to put money in expensive parts, so I only use originals.
I have cast iron big-bore cylinder that was on one of the engines I acquired and was thinking of making a sleeve for it to get it back to 50cc, and the advantage of the sleeve would be that I can use the sleeve to make a much wider double V-shaped exhaust port (compared to the original single port) gaining a lot of blowdown.
I suppose option 4 would be ok using a cast iron liner with a cast iron cylinder ?
any ideas on the minimum thickness of the sleeve for the exhaust-bridge to survive ?
does it has to be a specific type of cast iron (meaning can I turn one out of an ordinary piece of cast iron) ?

[marsheng]

This is probably going to be the most valuable bit of I of I gain from this thread.

From those in the know, and you are about to make a new cylinder, would you use the same as below or is there something you may want to change?

The drawing shown by Jan in post #25655 showed an elder type RSW cylinder. Here are the RSA values.
A-ports timing 130°, roof angle 25°
B-ports timing 132°, roof angle 10°
C-port timing 132°, roof angle 50°

The next thing, if you have a non power valve exhaust, ie just a hole, would you change anything as above?

Lastly, would the port angles as above be different depending on bore ?

My guess is, it would all remain the same, but then I'm no expert.

What is the difference between RSW and RSA - If I search the forum I get - Nothing found. Probably to short for a search.

Thanks Wallace

[marsheng]

Jan used a morse cone angle (3° included angle if memory serves) on the cylinder bore inside and the sleeve's outside.
Of course you need not use a plated light-alloy liner; you can do the same thing with a cast-iron liner.

The problem with this could be that the insert and ports don't match. If I have my maths correct, 0.026 mm change in OD means the sleeve goes in 1 mm further.

I can see this being a great development tool. At the track, pop out the old liner and insert the new. You would need to make sure that cylinder head still seals correctly.

I have used straight sleeves many times and just heat is enough to drop the old sleeve out.

[F5 Dave]

If you are casting your own barrel there would have to be some super compelling reasons to not make a bridged or triple ex port. Esp without a PV.

But you want the ally tunnels well attached to the bore surface to strip heat away.
You'd still have to gain more than you'd achieve optomising ports on a single hole ex.

And presumably you will keep it period air cooled or Bears only so no concern?

I could send you a Rotax style pressure PV which could be a fairly easy mod to a water cooled arrangement.

[marsheng]

If you are casting your own barrel there would have to be some super compelling reasons to not make a bridged or triple ex port. Esp without a PV.

But you want the ally tunnels well attached to the bore surface to strip heat away.
You'd still have to gain more than you'd achieve optomising ports on a single hole ex.

And presumably you will keep it period air cooled or Bears only so no concern?

I could send you a Rotax style pressure PV which could be a fairly easy mod to a water cooled arrangement.

I do have a bridged port. What I meant by big holes is , no power valves or aux exhaust ports.

Needs to be period - Pre 82. I have a water cooled barrel here with a pressure type exhaust valve but that is 1983. Aghaaa.

[husaberg]

I do have a bridged port. What I meant by big holes is , no power valves or aux exhaust ports.

Needs to be period - Pre 82. I have a water cooled barrel here with a pressure type exhaust valve but that is 1983. Aghaaa.

The 125 Maico rs road race bikes were water cooled in the 70s as well as being disc valve induction
Pretty sure most mods are okay as long as they are undisguisable with regards to the outside appearance.
https://i.ytimg.com/vi/RVR4ZWINzW8/hqdefault.jpg
http://www.zweitakte.de/modelle/renn/maicoRS250proto.htm

1979 Maico MD250 road bike
http://databikes.com/imgs/a/d/l/b/g/maico__md_250_wk_1979_5_lgw.jpg
MAICO MD 250 WK-Cup machine
http://moto.zombdrive.com/images/maico-md-250-wk-9.jpg

Its only cheating if you get caught
https://www.carthrottle.com/post/wqm9665/

[Grumph]

Needs to be period - Pre 82. I have a water cooled barrel here with a pressure type exhaust valve but that is 1983. Aghaaa.

If I can be looking at water cooling my "pre63" Villiers special on the basis of one pommy karter building a water cooled 9E in 1962, you've got no worries watercooling the Maico. You've simply found one of the rare 250 race bikes....

Precedent is everything.

[husaberg]

If I can be looking at water cooling my "pre63" Villiers special on the basis of one pommy karter building a water cooled 9E in 1962, you've got no worries watercooling the Maico. You've simply found one of the rare 250 race bikes....

Precedent is everything.

http://i48.tinypic.com/kd1yyf.jpg
even looks like it has an Aprilia/Rotax RAVE power valve........
1934-1940 The XIVA (RY).water cooled with autolube or petroloil
http://www.users.globalnet.co.uk/~pattle/nacc/arc0596.htm

[Frits Overmars]

From those in the know, and you are about to make a new cylinder, would you use the same as below or is there something you may want to change?
The drawing shown by Jan in post #25655 showed an elder type RSW cylinder. Here are the RSA values.
A-ports timing 130°, roof angle 25°
B-ports timing 132°, roof angle 10°
C-port timing 132°, roof angle 50°
if you have a non power valve exhaust, ie just a hole, would you change anything as above?No.


would the port angles as above be different depending on bore?Not depending on the bore, but on the stroke/bore-ratio.
330479


What is the difference between RSW and RSA.There is no difference in the porting of the late-model RSW and RSA cylinders.
But the RSA has better cooling (channels inside the inner curvatures of the transfer ducts) and two extra head studs that somehow contributed to power.
330480

[Frits Overmars]

Jan used a morse cone angle (3° included angle if memory serves) on the cylinder bore inside and the sleeve's outside.
Of course you need not use a plated light-alloy liner; you can do the same thing with a cast-iron liner.
The problem with this could be that the insert and ports don't match. If I have my maths correct, 0.026 mm change in OD means the sleeve goes in 1 mm further.Mathematically you're right. But that is without considering the press fit. It will not take much force to move the sleeve a little deeper.

[Frits Overmars]

The 125 Maico rs road race bikes were water cooled
https://i.ytimg.com/vi/RVR4ZWINzW8/hqdefault.jpg
I'd rather say they had a water cooled head cover. Coolant in the cylinder was hardly moving; cooling below the exhaust was non-existent.
Not the best solution if you want reliable power.

[philou]

No.

Not depending on the bore, but on the stroke/bore-ratio.
330479


I do not understand the calculation

Example A-port stroke 54,5 bore 54

0,46 X 54,5 / 54 = 0,462

Editing : i'm crazy. I have forgot "atn"

[jamathi]

I'd rather say they had a water cooled head cover. Coolant in the cylinder was hardly moving; cooling below the exhaust was non-existent.
Not the best solution if you want reliable power.

Such a Maico engine gave 27HP

[husaberg]

I'd rather say they had a water cooled head cover. Coolant in the cylinder was hardly moving; cooling below the exhaust was non-existent.
Not the best solution if you want reliable power.

Progress aye, it was still more uniform i'd wager than the air cooling.
Out of interest Frits how common where the water cooled disc Maico 250 road bikes?


Seen this today neat
https://grabcad.com/library/aprilia-rsw-125-250-cylinder-incompl-1
seeing one in 3d is pretty neat
Needs a little work on the AUX exhaust

I am surprised no one commented on this?
where te pic is click on the link where is says load in 3d viewer and play with your mouse
330482330481

[Frits Overmars]

Out of interest Frits how common where the water cooled disc Maico 250 road bikes?Hen's teeth. I've never seen one in the flesh. And can you imagine Maico not only built a 250 cc cylinder on their 125 cc cases; they also built a 50 on the same cases. Apparently aesthetics were not part of the company policy. Neither was survival, as we now know. I was invited to visit the Maico racing department in the 70s. They had electric light, which was more than could be said of the series production facilities. Workers had to make do with the scarce light entering through the roof windows.


I am surprised no one commented on this? where te pic is click on the link where is says load in 3d viewer and play with your mouse.
https://grabcad.com/library/aprilia-rsw-125-250-cylinder-incompl-1
330482330481Nice job.
The cylinder is an APC, an elderly type, recognizable because the edges between the bore and the transfer duct entries at the cylinder base are still sharp, not radiused.

[shnaggs]

I am surprised no one commented on this?
where te pic is click on the link where is says load in 3d viewer and play with your mouse
330482330481


Husa, I was intrigued earlier by this but was having difficulties loading it in my CAD software. Now that you bring to our attention that we can view the cylinder in their 3D workspace is great!

Anyone else notice that there are 2 extra A ports and B ports in the drawling laid on top of each other??? You can de-select the bodys on the left hand side to view them better. Is this a goof by the designer? Or was there a version that had bigger transfer ducts???

[Norman]

Progress aye, it was still more uniform i'd wager than the air cooling.
Out of interest Frits how common where the water cooled disc Maico 250 road bikes?



I am surprised no one commented on this?
where te pic is click on the link where is says load in 3d viewer and play with your mouse
330482330481


I made a few cuts in the model and copy paste pictures on the inside of the RSW cylinder from GrabCad. Very interesting!

[husaberg]

Hen's teeth. I've never seen one in the flesh. And can you imagine Maico not only built a 250 cc cylinder on their 125 cc cases; they also built a 50 on the same cases. Apparently aesthetics were not part of the company policy. Neither was survival, as we now know. I was invited to visit the Maico racing department in the 70s. They had electric light, which was more than could be said of the series production facilities. Workers had to make do with the scarce light entering through the roof windows.

Nice job.
The cylinder is an APC, an elderly type, recognizable because the edges between the bore and the transfer duct entries at the cylinder base are still sharp, not radiused.

The 3d rendering is not mine i should point out.
Flet has my APC copy cylinder and patterns at the moment He is going to run of a few cylinders for some people.
The Maico story is an intersting one esp with the MX bikes.
They had at the time the best open class bike in the world ruined by silly cost cutting (some say internal conspiracy)that they never recovered from.


Husa, I was intrigued earlier by this but was having difficulties loading it in my CAD software. Now that you bring to our attention that we can view the cylinder in their 3D workspace is great!

Anyone else notice that there are 2 extra A ports and B ports in the drawling laid on top of each other??? You can de-select the bodys on the left hand side to view them better. Is this a goof by the designer? Or was there a version that had bigger transfer ducts???

I think its incomplete, there is a few little other errors i noticed arround the AUX entries to the main duct

I made a few cuts in the model and copy paste pictures on the inside of the RSW cylinder from GrabCad. Very interesting!
Nice

There are Nsr125, NSR250 and RS125 sectioned cylinders and 3d models to compare them to on the net.
http://thetrxproject.blogspot.co.nz/2013/04/
330489330490330491330492330493330494

[lodgernz]

This is probably going to be the most valuable bit of I of I gain from this thread.

From those in the know, and you are about to make a new cylinder, would you use the same as below or is there something you may want to change?

The drawing shown by Jan in post #25655 showed an elder type RSW cylinder. Here are the RSA values.
A-ports timing 130°, roof angle 25°
B-ports timing 132°, roof angle 10°
C-port timing 132°, roof angle 50°

The next thing, if you have a non power valve exhaust, ie just a hole, would you change anything as above?

I thought I read domewhere on this thread, that a non-PV engine should have the A-transfers open before the Bs?

[wobbly]

Those transfer port numbers were used with a 3 port Exhaust that had a huge top radius timed at 79*EPO,so was at the absolute outer limit in every respect.
It also had a power valve that wasnt fully up till around 12,000,only 800rpm away from peak.
Deleting the powervalve would basically destroy all the mid power capability, thus the engine would need a major rethink regarding its STA distribution.
It would not be able to have anything like the STA's needed by the peak power generated by those timings for the Aprilia.
Thus reverting to non reverse stagger and much lower timings are needed, as this configuration naturally generates better powerband width,at the expense of outright peak and
overev - due to the natural effects of the scavenging regime.
At a guess I would opine at A 115.5, B 117, C 118.

[TZ350]

.

The old det sensor had been buzzing away during full power runs. Didn't matter how rich I made it or how advanced or retarded the ignition or how open the PV was. I suspected the piston might be hitting the head again and ringing the det sensor. So I popped the head off.

330514 330518

No signs of detonation or the piston hitting the head but curiously there was this small 3mm id washer???????

Without any marks on the piston/head its hard to believe the washer was the problem. Maybe it dropped in there when I took the plug out, but where could it come from? There is nothing immediately obvious missing.... :scratch:

330519

The head cover has different sized water channels so the water flow is biased to flow across the back of the combustion chamber insert from one side to the other.

330517

With the head off, it was a good time to see what mV servo feedback value corresponded to what PV open position.

For my setup the numbers came out at.

mV ATDC Duration
2.3 = 95 ... 170
2.4 = 93 ... 174
2.5 = 90 ... 180
2.6 = 86 ... 188
2.7 = 84 ... 192
2.8 = 82 ... 196
2.9 = 80 ... 200
3.0 = 78.5. 203

330515

Now that I know what Exhaust duration corresponds to what mV servo position. Instead of opening the PV in a straight line I could try taking advantage of the symbiotic resonance between port and pipe that happens with an exhaust duration of 192 deg. And only opening it further as the exhaust STA runs out. That way I might be able to take advantage of the symbiotic resonance to plump up the lower part of the torque curve.

330516

Another interesting feature of the Ignitec ignition is that the PV servo position can be mapped TPS vis RPM. I might be able to use this to improve the trapping efficiency at high RPM and low TPS by closing it, at say below 20% TPS for improved EFI throttle roll on after shutting off for a corner.

[breezy]

330520 Jan / Frits do you think there would be an benefits from unmasking the smaller transfer port by the barrel spigot? :sherlock:

[jamathi]

330520 Jan / Frits do you think there would be an benefits from unmasking the smaller transfer port by the barrel spigot? :sherlock:

Yes, I think so!

[136kg136ps]

Those transfer port numbers were used with a 3 port Exhaust that had a huge top radius timed at 79*EPO,so was at the absolute outer limit in every respect.
It also had a power valve that wasnt fully up till around 12,000,only 800rpm away from peak.
Deleting the powervalve would basically destroy all the mid power capability, thus the engine would need a major rethink regarding its STA distribution.
It would not be able to have anything like the STA's needed by the peak power generated by those timings for the Aprilia.
Thus reverting to non reverse stagger and much lower timings are needed, as this configuration naturally generates better powerband width,at the expense of outright peak and
overev - due to the natural effects of the scavenging regime.
At a guess I would opine at A 115.5, B 117, C 118.

Wob,would using an ATAC allow you to use the transfer numbers you quoted earlier if an PV was unavailable?

[Norman]

The 3d rendering is not mine i should point out.
Flet has my APC copy cylinder and patterns at the moment He is going to run of a few cylinders for some people.
The Maico story is an intersting one esp with the MX bikes.
They had at the time the best open class bike in the world ruined by silly cost cutting (some say internal conspiracy)that they never recovered from.



I think its incomplete, there is a few little other errors i noticed arround the AUX entries to the main duct

Nice

There are Nsr125, NSR250 and RS125 sectioned cylinders and 3d models to compare them to on the net.
http://thetrxproject.blogspot.co.nz/2013/04/
330489330490330491330492330493330494

As I have a little bit of a problem visualizing the air flow through cylinder transfers I asked a CFD guy at work to show me his tools and if he at the same time could do a quick flow visualization of the RSW cylinder. With my limited 3D knowledge a made a bottom end (crankcase substitute, not perfect or anything like the original..) to connect to the cylinder and we put the piston at BDC. I asked him to send 0,04 kg/s into the bottom inlet channel to see how it looked like. I hope it is not that far from an air flow that could be seen. Changing the flow between 0,01 to 0,04 kg/s did not change the flow pattern so much, if I remember correctly.

I think we got close to 0,16 bar pressure difference from inlet to outlet at this flow.

Please note that it is a steady state flow right through the cylinder and without the actual very transient situation during operation. I guess it cannot be much more simplified than this. Can it possibly indicate how the flow would look like just before the return pulse stops the flow and pushes back into the cylinder? See pictures attached.

Please note that all pictures represents 0,04 kg/s even if otherwise stated.

Jan Thiels statement that the flow is attached to the bottom of the transfers, is clearly also observed in the simulations!

[Frits Overmars]

Now that I know what Exhaust duration corresponds to what mV servo position. Instead of opening the PV in a straight line I could try taking advantage of the symbiotic resonance between port and pipe that happens with an exhaust duration of 192 deg. And only opening it further as the exhaust STA runs out. That way I might be able to take advantage of the symbiotic resonance to plump up the lower part of the torque curve.Good thinking. But remember that, even with 192° exhaust timing, at low revs the first return pulse will arrive at the cylinder too early.
You ought to combine it with a trombone pipe.


Another interesting feature of the Ignitec ignition is that the PV servo position can be mapped TPS vis RPM. I might be able to use this to improve the trapping efficiency at high RPM and low TPS by closing it, at say below 20% TPS for improved EFI throttle roll on after shutting off for a corner.High rpm means diminishing blowdown time.area, so the pressure of the spent, hot gases in the cylinder at the end of the blowdown phase will increase.
If you close the throttle as well, the scavenging pressure is sure to drop below this cylinder pressure, the spent gases will enter the transfer ducts and you'll get detonation like you've never seen before.

[TZ350]

Good thinking. But remember that, even with 192° exhaust timing, at low revs the first return pulse will arrive at the cylinder too early.
You ought to combine it with a trombone pipe.
Good idea, :eek: thanks, a trombone pipe has been a bit of a dream, it may be possible .... :scratch:


High rpm means diminishing blowdown time.area, so the pressure of the spent, hot gases in the cylinder at the end of the blowdown phase will increase.

If you close the throttle as well, the scavenging pressure is sure to drop below this cylinder pressure, the spent gases will enter the transfer ducts and you'll get detonation like you've never seen before.

Knowing that lowering the pressure in the pipe at the lower end of the rev range increases power there (Red line). I was thinking of having a rotary pressure bleed valve activated by the same servo as controls the PV. So as the PV closes the exhaust port pressure bleed opens. The pressure bleed valve could be a drum with a slot so the valve area opens/closes quickly.

330531

Pressure bleed, Red open, Blue closed.

[philou]

The fospipe concept works on low bmep engines ?

I have to make an exhaust for a friend who has mounted a husqvarna 360 engine in a chassis of 125 rs aprilia :rayure:

I do not have the original exhaust to have a starting base.
The original is not suitable for circuit use. Allez terrain motorcycle

[Frits Overmars]

Knowing that lowering the pressure in the pipe at the lower end of the rev range increases power there (Red line). I was thinking of having a rotary pressure bleed valve activated by the same servo as controls the PV. So as the PV closes the exhaust port pressure bleed opens.Bleeding the pipe will drop the average pipe pressure but this will hardly speed up the blowdown phase which is already partly sonic. And you cannot speed up a sonic flow by lowering the downstream pressure. Bleeding may work indirectly to some extent as it will weaken the exhaust pulses and therefore the engine power and the mass of exhaust gases.

[Frits Overmars]

The fospipe concept works on low bmep engines ?Yes, you can compensate by entering a low value for the speed of sound; that should get you in the ball park.

[philou]

thank you very much

[breezy]

Yes, I think so!

Thanks for reply. :sunny:

[lohring]

As I have a little bit of a problem visualizing the air flow through cylinder transfers I asked a CFD guy at work to show me his tools and if he at the same time could do a quick flow visualization of the RSW cylinder. With my limited 3D knowledge a made a bottom end (crankcase substitute, not perfect or anything like the original..) to connect to the cylinder and we put the piston at BDC. I asked him to send 0,04 kg/s into the bottom inlet channel to see how it looked like. I hope it is not that far from an air flow that could be seen. Changing the flow between 0,01 to 0,04 kg/s did not change the flow pattern so much, if I remember correctly.

I think we got close to 0,16 bar pressure difference from inlet to outlet at this flow.

Please note that it is a steady state flow right through the cylinder and without the actual very transient situation during operation. I guess it cannot be much more simplified than this. Can it possibly indicate how the flow would look like just before the return pulse stops the flow and pushes back into the cylinder? See pictures attached.

Please note that all pictures represents 0,04 kg/s even if otherwise stated.

Jan Thiels statement that the flow is attached to the bottom of the transfers, is clearly also observed in the simulations!

Attached is an Article I edited from two articles. the second is a CFD analysis of an Aprilia cylinder that is very interesting.

Lohring Miller

[DaisyB]

Yes, you can compensate by entering a low value for the speed of sound; that should get you in the ball park.

Errr, just how low Frits?
Cheers

[wobbly]

ATAC in general works much lower down the powerband than a powervalve does, and cannot be gradually reduced in its effect.
It works very well to reduce the effect of the pipes return pulse being way too early at lower rpm, but this effect kills the power badly as soon
as the pipe efficiency starts to rise - thus the valve connecting the Helmholtz chamber to the pipe must be switched instantly at a specific rpm.
In a 125 race engine the ATAC would be off at around 8000 rpm, where as the PV may not be closed fully to within 1000 rpm of peak power.

[136kg136ps]

Thanks for that Wob,and to Frits for the tip on reducing the speed of sound.

[Norman]

Attached is an Article I edited from two articles. the second is a CFD analysis of an Aprilia cylinder that is very interesting.

Lohring Miller

Yes, very interesting. Thank you. I understand the importance to have good flowing transfers in combination with the very best flow pattern..

[Frits Overmars]

Yes, you can compensate by entering a low value for the speed of sound; that should get you in the ball park.
Errr, just how low Frits?That's not a serious question, is it Daisy? Because if it was, I would need to know about a hundred things regarding your engine before I could give a more or less accurate estimation.
Just pick a value between 350 and 550 m/sec, build a pipe, see where the rpm of maximum power is, and if it is not where you want it to be, adapt your picked value accordingly. If your first pipe isn't already in the ball park, your second one should be. It's not that difficult.

[Haufen]

Attached is an Article I edited from two articles.

Thanks, looks interesting! Could you please provide links / information on the two original articles, too?

[lohring]

Thanks, looks interesting! Could you please provide links / information on the two original articles, too?

Unfortunately, I lost the links to the articles. A google search didn't find them either. I'll look some more.

Lohring Miller

[Vannik]

Unfortunately, I lost the links to the articles. A google search didn't find them either. I'll look some more.

Lohring Miller

One part of the article.

330586

[seattle smitty]

Geeting here maybe late to add my one-cent worth to Marsheng's sleeve topic, but here's another possible (??) option: In outboard racing, with a lake full of cool water rammed into, through, and out, iron-sleeved engines have worked fine, with sufficient heat transfer. Konig's engines, which came with cast-in iron sleeves (of varied quality, and often replaced with home-made sleeves) had a feature you could think about. The upper maybe 35mm of the sleeve was directly exposed to water. This part had a somewhat larger outside diameter than the rest of the sleeve, acting as a flange against the aluminum block casting, a few mm above the top of the exhaust port. Try this link for a photo of a similar sleeve: https://www.google.com/search?q=konig+outboard+cylinder+sleeve&tbm=isch&tbo=u&source=univ&sa=X&ved=0ahUKEwiA4rCksc_TAhVQ32MKHQxEA2sQsAQIIQ&biw=1472&bih=717#imgrc=PRer3O4OYxIa1M:&spf=212

Now, the upper part of that outboard motor sleeve, directly exposed to water, is smooth. For a motorcycle that has to carry its own supply of much warmer water, how about making your iron sleeve with that upper section of a much larger O.D. so that you could then take something like a narrow parting tool and turn a series of cooling fins, for water rather than air, into that section? Would that greatly increased area of exposure to coolant answer the problem of heat transfer, while leaving you with what you might see as the advantages of a (properly-fit) pressed or heat-shrunk iron sleeve? Many existing cylinders could not be altered to take this sleeve configuration, but some could.

[Tim Ey]

See pictures attached.

Please note that all pictures represents 0,04 kg/s even if otherwise stated.

Jan Thiels statement that the flow is attached to the bottom of the transfers, is clearly also observed in the simulations!

Hey Norman,
may you show us some colored section views through the exhaust ports? I would like to see the speeds in the exhaust - specialy in the auxilaries.

I have an idea what might have been the problem on those exhausts of the early Aprilia / Rotax cylinders. The exhausts of the latest cylinders are looking quite different.

Thank you (and your colleague) for this very informative work!
Kindest Regards
Tim

[G Jones]

Yes, you can compensate by entering a low value for the speed of sound; that should get you in the ball park.Just thought I'd put the numbers from a TZ350 into the Fospipe tool - @10500rpm target rpm - the exhaust length is near the same as TZ350G pipe - (whatever target HP is entered) - although the belly diameter is significantly larger (110 > 141.8) ...good starting point ?

[wobbly]

The 3G3 TZ works well with the 960 odd TL, but you would have to be a genius pipe builder to get a set any fatter than 110 to fit on the thing.

[Grumph]

The 3G3 TZ works well with the 960 odd TL, but you would have to be a genius pipe builder to get a set any fatter than 110 to fit on the thing.

Should be possible to fit on a sidecar....But is it worth doing ?

[husaberg]

The 3G3 TZ works well with the 960 odd TL, but you would have to be a genius pipe builder to get a set any fatter than 110 to fit on the thing.

I remember someone saying not to go over 110mm on any of the yamaha early twins up to the TZR's to avoid over scavenging an already too small crankcase?

[Frits Overmars]

Konig's engines, which came with cast-in iron sleeves (of varied quality, and often replaced with home-made sleeves) had a feature you could think about.Smitty, nowadays I wouldn't attach too much value to the details of a 500 cc four-cylinder two-stroke racing engine that produces 75 hp on petrol.
And I would not advocate the use of iron sleeves in any case.

[G Jones]

Should be possible to fit on a sidecar....But is it worth doing ?Sidecar is the intended use...
When I built a new chassis - and new bodywork - I tried to leave a lot more room for the pipes than the previous bike had - on that bike the bodywork was very close to the 110mm pipes...

In view of Husaberg's comments re
"over scavenging a already small crankcase?"maybe not worth the effort - unless there are other things that can be adjusted to suit the fatter pipes.

[G Jones]

I thought it was interesting to see how close the 2 pipes were - apart from the fat belly of course - whether it's any use is another thing entirely...

[Frits Overmars]

Just thought I'd put the numbers from a TZ350 into the Fospipe tool - @10500rpm target rpm - the exhaust length is near the same as TZ350G pipe - (whatever target HP is entered) - although the belly diameter is significantly larger (110 > 141.8) ...good starting point ?
I thought it was interesting to see how close the 2 pipes were - apart from the fat belly of course - whether it's any use is another thing entirely...
330632

I'd like to make it clear that this 'Fospipe tool' that you used, does not come from me. You only need to look at the number of cones. Here is my FOS exhaust concept:
330633

[G Jones]

I'd like to make it clear that this 'Fospipe tool' that you used, does not come from me. You only need to look at the number of cones. Here is my FOS exhaust concept:
I apologise for that - I hadn't realised that your original idea had been used by someone else - although they do call it "fospipe" - with a few experimental pipe additions - again sorry if I caused you any problems..

[Frits Overmars]

I apologise for that - I hadn't realised that your original idea had been used by someone else - although they do call it "fospipe" - with a few experimental pipe additions -
again sorry if I caused you any problems..No worries; you didn't. But I'd prefer that people who write programs using my concepts, wouldn't attach my name to their products.

[wobbly]

The TZ350 - 3G3 with six transfer ports is very happy with much fatter pipes - perfect on a sidecar setup.
It has little to do with the case volume, and everything to do with the transfers ability to control the scavenging streams at BDC when the diffuser is sucking like hell on the Ex port.
The 6 port configuration has much better ducts, and the smaller individual ports have way better ability to keep the in flowing streams coherent.
You are right though, the volume is too small, but thats easily fixed by utilizing RD400 cases.
If you are really keen then use the 3G3 casting and weld on reed boxes, making it like a Kenny Roberts OW of the period.
This then allows another couple of boost ports up the back.
The very best setup though in this case would be a G - 250 cylinder bored to 64,the reeds welded on and the cylinder turned around.
If you then use waisted studs, the inlet port width can be huge, and you can also add Aux Ex ports.
A killer engine, that is as we speak, being built to go into a LSR streamliner.

[peewee]

You are right though, the volume is too small, but thats easily fixed by utilizing RD400 cases.
.

don't know what size the pins are but maybe can use the ktm118 rods. its still collecting dust in the corner of the garage but I put some 118rods and Suzuki thrust washers on my banshee. fit like a glove :woohoo:. cant remember the wristpin but I think its Suzuki also, been a while since I been to that corner of the garage :lol:

[F5 Dave]

Well I've finally managed to get some time again and dynod the RZ350 (+7mm crank and CPI barrels 496cc) with the 8 plate clutch. And after, ahem, tying it down a bit tighter, got some readings where it actually peaked without spinning up and losing the trace. But all is not rosy. Its got a decent hole in the power. 6 transfers but ducts aren't marvelous.

So I took the fuse out of the ypvs control and you can see it fills the gap from 6200-7200. I'll have to sort that with a new controller or go Ignitech. But the dip from 5500-6 stays. I take airbox off and that really helps the rest of the curve, but ran out of jets to see if that's just mixture. A jet leaner without doesn't help that area appreciably. And that 5-6 dip remains.

First pic PV locked low vs opening but too early. Click 3 times.
2nd pic without airbox.

Bearing in mind this is a roadbike and I chose 35mm pwk to try bolster lower revs. I was rolling it on to full from just below 5ish.

Thoughts?

[husaberg]

don't know what size the pins are but maybe can use the ktm118 rods. its still collecting dust in the corner of the garage but I put some 118rods and Suzuki thrust washers on my banshee. fit like a glove :woohoo:. cant remember the wristpin but I think its Suzuki also, been a while since I been to that corner of the garage :lol:
330642
KTM200SX-EXC ’98-16
Ø Small End (A) 20.00mm
Ø Big End (B) 28.00mm
Center to Center (C)118.00mm
Width Small End (D)15.90mm
Width Big End (E 15.90mm
Total Length (F) 151.40mm
Eye to Eye Center (G) 94.00mm
Ø Big End Pin (H) 22.00mm
Length Big End Pin (I) 55.00mm
Washers 22 x 37 x 1.0mm
Remarks Barreled Rod

RD250 + RD350 Air Cooled -360-
Ø Small End (A) 20.00mm
Ø Big End (B) 28.00mm
Center to Center (C)110.00mm
Width Small End (D)16.00mm
Width Big End (E)16.00mm
Total Length (F) 141.50mm
Eye to Eye Center (G)86.mm
Ø Big End Pin (H) 22.00mm
Length Big End Pin (I) 50.75mm
Washers 22 x 37 x 1.0mm

RD400 ’76-79 -1A1/2T2-
Ø Small End (A)20.00mm
Ø Big End (B)28.00mm
Center to Center (C)115.00mm
Width Small End (D)16.00mm
Width Big End (E)16.00mm
Total Length (F) 147.00mm
Eye to Eye Center (G) 91.00mm
Ø Big End Pin (H) 22.00mm
Length Big End Pin (I) 51.00mm
Washers 22 x 37 x 1.0mm


The TZ350 - 3G3 with six transfer ports is very happy with much fatter pipes - perfect on a sidecar setup.
It has little to do with the case volume, and everything to do with the transfers ability to control the scavenging streams at BDC when the diffuser is sucking like hell on the Ex port.
The 6 port configuration has much better ducts, and the smaller individual ports have way better ability to keep the in flowing streams coherent.
You are right though, the volume is too small, but thats easily fixed by utilizing RD400 cases.
If you are really keen then use the 3G3 casting and weld on reed boxes, making it like a Kenny Roberts OW of the period.
This then allows another couple of boost ports up the back.
The very best setup though in this case would be a G - 250 cylinder bored to 64,the reeds welded on and the cylinder turned around.
If you then use waisted studs, the inlet port width can be huge, and you can also add Aux Ex ports.
A killer engine, that is as we speak, being built to go into a LSR streamliner.

I fully understand how close the bore centers are now on a RD250-350-400
I have one appart, talk about cramped, so the 6 port makes sense.
I can see why yamaha did it as they wanted to keep it slim,rocking couple etc. but odd they never chose to offset the transfers like a T500/GT750 or a works H2R.
330643
Small case volume is likely why the H2R's went better with the std road porkchopped flywheels than the full circle ones they tried.
330644

[Norman]

Hey Norman,
may you show us some colored section views through the exhaust ports? I would like to see the speeds in the exhaust - specialy in the auxilaries.

I have an idea what might have been the problem on those exhausts of the early Aprilia / Rotax cylinders. The exhausts of the latest cylinders are looking quite different.

Thank you (and your colleague) for this very informative work!
Kindest Regards
Tim

Here are a few more pictures showing the velocities in the exhaust. It should give a picture but i keep in mind that I have been told that the calculation grid (mesh) still could do with some refinements and more refinements still. I have also been told (yes I tried to push a little) that doing a fully dynamic cycle, possibly with combustion and everything is quite complicated and I think we would have needed more 2-stroke knowledge. Unfortunately, we have to work with others things during working hours for a while now..:(.

[peewee]

husa my memory isnt great so ill have to take a look why i used the suzuki thrust washers and small end bearing. maybe the banshee rods are different than what you listed ? ill have a look tomorow. oh ya, between the +4 stroke and the 118 rod, i had to trench the cases also

[DaisyB]

That's not a serious question, is it Daisy? Because if it was, I would need to know about a hundred things regarding your engine before I could give a more or less accurate estimation.
Just pick a value between 350 and 550 m/sec, build a pipe, see where the rpm of maximum power is, and if it is not where you want it to be, adapt your picked value accordingly. If your first pipe isn't already in the ball park, your second one should be. It's not that difficult.

Thanks Frits, sorry just meant should I be looking at couple of percent off or 50, trying to avoid building to many pipes!

[husaberg]

husa my memory isnt great so ill have to take a look why i used the suzuki thrust washers and small end bearing. maybe the banshee rods are different than what you listed ? ill have a look tomorow. oh ya, between the +4 stroke and the 118 rod, i had to trench the cases also

The Pro X cattledog listed the bearing type as well lots to choose from.

[guyhockley]

The TZ350 - 3G3 with six transfer ports is very happy with much fatter pipes - perfect on a sidecar setup.
It has little to do with the case volume, and everything to do with the transfers ability to control the scavenging streams at BDC when the diffuser is sucking like hell on the Ex port.
The 6 port configuration has much better ducts, and the smaller individual ports have way better ability to keep the in flowing streams coherent.
You are right though, the volume is too small, but thats easily fixed by utilizing RD400 cases.
If you are really keen then use the 3G3 casting and weld on reed boxes, making it like a Kenny Roberts OW of the period.
This then allows another couple of boost ports up the back.
The very best setup though in this case would be a G - 250 cylinder bored to 64,the reeds welded on and the cylinder turned around.
If you then use waisted studs, the inlet port width can be huge, and you can also add Aux Ex ports.
A killer engine, that is as we speak, being built to go into a LSR streamliner.
Bit of a fuzzy picture, sorry, I had to extract it from a pdf that was too big.
Just thought it made an interesting comparison, old school to now.
Not sure why they confused things by mixing in the RD...

[husaberg]

Bit of a fuzzy picture, sorry, I had to extract it from a pdf that was too big.
Just thought it made an interesting comparison, old school to now.
Not sure why they confused things by mixing in the RD...

https://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=326788&d=1481612951330656

[G Jones]

Bit of a fuzzy picture, sorry, I had to extract it from a pdf that was too big.
Just thought it made an interesting comparison, old school to now.
Not sure why they confused things by mixing in the RD...Do you have the original PDF still ?
(Are you any relation to Austin Hockley ?)

[guyhockley]

Do you have the original PDF still ?
(Are you any relation to Austin Hockley ?)
Yes and not as far as I know.
Hopefully this should get you it...
https://www.dropbox.com/s/u8oldz4urrg7oqc/Eckerold%27s%20portmap%20-%20Motorrad%20Classic.pdf?dl=0


(https://www.dropbox.com/s/u8oldz4urrg7oqc/Eckerold%27s%20portmap%20-%20Motorrad%20Classic.pdf?dl=0)

[G Jones]

Yes and not as far as I know.
Hopefully this should get you it...
https://www.dropbox.com/s/u8oldz4urrg7oqc/Eckerold%27s%20portmap%20-%20Motorrad%20Classic.pdf?dl=0Many Thanks ! - just in case you didn't know - Austin Hockley was a good runner in (mostly) 125 class back in the days of the Yamaha 125 twins...

[guyhockley]

Many Thanks ! - just in case you didn't know - Austin Hockley was a good runner in (mostly) 125 class back in the days of the Yamaha 125 twins...
Yeah, I remember him. Used to be Granby's rider at one point?
I also think I remember you and/or your brother posting on the TZ forum a bit worried because your TZ350 had dynoed in the 60s and your competitors were all claiming much bigger numbers from Banshee based engines.
You then had a pretty good season as I recall!

[G Jones]

Yeah, I remember him. Used to be Granby's rider at one point?
I also think I remember you and/or your brother posting on the TZ forum a bit worried because your TZ350 had dynoed in the 60s and your competitors were all claiming much bigger numbers from Banshee based engines.
You then had a pretty good season as I recall!Yes - Austin did ride the Granby bike - and a few others I guess - pretty sure Clive Horton too...
Must be a namesake of mine - although I have spent some time on the TZ forum - I've not dyno'd my bike - something I think we'll have to do with any pipe changes - we've also some plans to try some different carbs at some point - although - not a lot of places to race the thing any more...
As for Banshee bigger numbers - was never convinced...water under bridge now...

[seattle smitty]

Smitty, nowadays I wouldn't attach too much value to the details of a 500 cc four-cylinder two-stroke racing engine that produces 75 hp on petrol.
And I would not advocate the use of iron sleeves in any case.

I was using the old Konig sleeve as a starting point to explain an idea. But whatever.

[guyhockley]

snip
The very best setup though in this case would be a G - 250 cylinder bored to 64
snip
Does this only apply to the Gs? I have TZ 250 and 350 cylinders, D and E, and I'm sure the 250 has more room between water jacket and outer barrel, they're in a different place to me at the moment so I can't check. I looked before and wondered if the 250 could take going out to the 59-60 range for a squarish 350.
OTOH just found this and looks very much like an underbored 350...
http://www.ebay.co.uk/itm/YAMAHA-CYLINDER-BARREL-JUG-TZ250-TZ-250-1973-ROAD-RACER/360698287717?_trksid=p2047675.c100013.m1986&_trkparms=aid%3D111001%26algo%3DREC.SEED%26ao%3D1% 26asc%3D43782%26meid%3D918d802341ae4174b31d8555159 1c303%26pid%3D100013%26rk%3D2%26rkt%3D3%26sd%3D262 005385275

[wobbly]

The 250G cylinder has much more modern transfer ports and ducts than anything previously.
Thus you could do the mods as per the Eckerold cylinder but using waisted studs allows the inlet to go even wider ( with a bridge of course ) allowing two extra boost ports
and you then dont have to add an Exhaust bridge as going 3 port is easy.
Turning the cylinder around is also easy and this makes the pipe headers straight, and then the inlet becomes dead straight onto the reed blocks with the carbs sitting horizontally.
The 350 period engine going into the LSR streamliner is as above, but uses a Banshee 58mm crank/115 rods with 61.5 Kawasaki pistons, making it a not so big overbore and close to square.

[guyhockley]

Thanks a lot. Interesting stuff.

[F5 Dave]

Well I've finally managed to get some time again and dynod the RZ350 (+7mm crank and CPI barrels 496cc) with the 8 plate clutch. And after, ahem, tying it down a bit tighter, got some readings where it actually peaked without spinning up and losing the trace. But all is not rosy. Its got a decent hole in the power. 6 transfers but ducts aren't marvelous.

So I took the fuse out of the ypvs control and you can see it fills the gap from 6200-7200. I'll have to sort that with a new controller or go Ignitech. But the dip from 5500-6 stays. I take airbox off and that really helps the rest of the curve, but ran out of jets to see if that's just mixture. A jet leaner without doesn't help that area appreciably. And that 5-6 dip remains.

First pic PV locked low vs opening but too early. Click 3 times.
2nd pic without airbox.

Bearing in mind this is a roadbike and I chose 35mm pwk to try bolster lower revs. I was rolling it on to full from just below 5ish.

Thoughts?

So I could try cranking in a bunch of advance at 5-7 and see what happens, but its not without its risks on unleaded with a 2D map as on the road it will spend a bunch of time part throttle near those revs cruising.

[FastFred]

.

Don't do it ...... or part throttle deto will ensue.

Somewhere TeeZee has a post about the results when he tried that.

[F5 Dave]

Im thinking I might have to ditch the zeeltronics and go ignitech so I can 1. Control the PV better, 2, buy and RGV TPS so I can make a 3D map. But only if that would help fill the hole, at least at full.
Wob, have you had this issue on CPI barrels to try fill in? Or perhaps your pipes were understandably better suited. Any ideas appreciated.

[wobbly]

There are three suspects.
1 - how much advance have you got at the rpm where the hole is - with the PV down at that rpm a bunch of advance at part throttle isnt going to detonate.
2 - seeing as the PV fills in the huge hole, I wonder if the blade is down far enough and or is it sitting at more than 0.5mm away from the piston when fully down.Any more than that and its leaking like a sieve and doing jack shit.
3 - The end of the needle may be too thin, as you said you were rolling on to WOT just below the hole. The mixture at WOT when at low rpm is set by the needle/tube annulus area, and this may simply be way too rich
as it hits full throttle.Try rolling on slower so the needle isnt fully up till over 7000,this will show whats going on with the fueling.

[F5 Dave]

26@5000 down to 24#7000. Was trying to be conservative on pump gas.

Yeah needles do need some more work, what I was running trying to tune around that porous cylinder isn't right now.

I matched the (flat) blades you got made real nice to the first barrel. They aren't as well matched to the current one. Maybe I should readdress that.

Thanks for the ideas.

[F5 Dave]

Er. . no.2. Surely if the PVs were leaking badly. Leaving fuse out holding them down, surely that would have little effect?

[richban]

Er. . no.2. Surely if the PVs were leaking badly. Leaving fuse out holding them down, surely that would have little effect?

Well I can vouch for the igntech PV control removing big holes in the curve of the 300 Honda's. Turned mountains into mole hills.

[F5 Dave]

Yeah, so I tried it opening as late as the dip switch modded Yam controller would allow (supposedly 7000 but seems like earlier) and then with it held closed. Closed till almost 8 wins.

[G Jones]

The 250G cylinder has much more modern transfer ports and ducts than anything previously.
Thus you could do the mods as per the Eckerold cylinder but using waisted studs allows the inlet to go even wider ( with a bridge of course ) allowing two extra boost ports
and you then dont have to add an Exhaust bridge as going 3 port is easy.
Turning the cylinder around is also easy and this makes the pipe headers straight, and then the inlet becomes dead straight onto the reed blocks with the carbs sitting horizontally.
The 350 period engine going into the LSR streamliner is as above, but uses a Banshee 58mm crank/115 rods with 61.5 Kawasaki pistons, making it a not so big overbore and close to square.Greatly appreciate your experience !
Thinking out loud...:rolleyes:- the last of the "normal" TZ250's - I'd forgotten that - wasn't that an odd size piston ? (4A1 ? cylinder) - or maybe thinking of something different...
The banshee +4 crank - I've never been able to find a supplier that lists one that isn't welded - does anyone supply them just pressed up with a separate crankpin ?
I did ask a few of the suppliers a couple of years ago - if they would supply just the wheels - I can put them together myself - but all negative answers...
I'd looked at the Kawasaki pistons a while back too - although in the places I've been looking - can only find pistons for KE175 at 61.5 & the KE175D at 62.5 - although I've a feeling I may have seen KH ? 500 at somewhere around those sizes - not looked recently...

[wobbly]

The PV when held down fills in that huge hole, but just maybe if it was to work " better " it would also fix the hole further down.

Re the 250 G cylinder, yes it had an odd bore size 54.4 I think,but using oversize Wossner H1 pistons at 61.5 diameter this isnt relevant ( 58 by 61.5 keeps it under 350 and doesn't need case trenching )

I build cranks for the RD series engines ( using modified Banshee parts ) and only the center pin is welded.These have Mallory added to the wheels so that
the crank can be balanced correctly for the stronger long rods and the pistons that are much heavier than the oem 250 ones the cranks were originally designed for.
They use rollers on the outside, and a 1/2 clip groove is added to the center main tunnel, as all the engines i do have straight cut low ratio primary gears - needed to achieve
the top speeds and keep normal sized sprockets.

[F5 Dave]

Right gotcha. Will try get back to dyno one night and try different throttle techniques to see if it alters. Will try dropping needles and think already on fat shallow taper but have about 3 other options.

Then will try crank some more advanced just to see if it can be used to change that area.

3rd option take it all apart again and rework or remake the blades.
Appreciate it.

[marsheng]

At Aprilia we never had any high tech equipment, just an EGT sensor.
Nothing else was needed for finding more power!

Please explain. On my Maico, the best I can get is around 500 deg. Does the egt depend on the motor and I assume if my max rpm is 8500, it may never get there.

[wobbly]

If you can only get to 500* then there is a serious problem.
It can only be a few issues that will cause this, way too much compression or timing for the fuel, or severe short circuiting.
I had the short circuiting problem on a 250 MX engine that had the Aux ground around to bore center.It ran just fine but when the piston was changed from a
Wossner to a Prox it ran like shit and would not respond to leaner jetting changes at all.
Finally in desperation I pulled it down ,to discover that the Wossner had a machined hole in the skirt above the small end that did not go around past the centerline.
The Prox had a huge cast in cutout,that was well past centerline and this was seriously joining the Aux and A transfer together as the piston passed over them.
Changing the piston fixed the jetting issue immediately,where previously it would run rich ( 500* ) no matter what jet was in it.
Any engine on petrol should be able to run past 600* in the header without any problems at all, no matter what the cc,rpm or bmep.

[shnaggs]

If you can only get to 500* then there is a serious problem.
It can only be a few issues that will cause this, way too much compression or timing for the fuel, or severe short circuiting.
I had the short circuiting problem on a 250 MX engine that had the Aux ground around to bore center.It ran just fine but when the piston was changed from a
Wossner to a Prox it ran like shit and would not respond to leaner jetting changes at all.
Finally in desperation I pulled it down ,to discover that the Wossner had a machined hole in the skirt above the small end that did not go around past the centerline.
The Prox had a huge cast in cutout,that was well past centerline and this was seriously joining the Aux and A transfer together as the piston passed over them.
Changing the piston fixed the jetting issue immediately,where previously it would run rich ( 500* ) no matter what jet was in it.
Any engine on petrol should be able to run past 600* in the header without any problems at all, no matter what the cc,rpm or bmep.

Wobbly, How close do you run your EGT probe to the port? I noticed on both the new KTM 125/250 MX bikes that I could not see EGT's over 1000*F. leaning it out didn't change much on the temp, but once I heard popping on over-rev, I then came back the other way. I did run the probe about 3" from the face of the pipe, so maybe I was too far away from the port face, making the readings a bit low?

[casal-fan]

Some wishful thinking:
330290


Presume you like the concept since you posted the picture?
If so, it makes me happy. I´m betting on the 72X72 config.

330856

[wobbly]

There are a couple of things in play that affect the egt reading of a perfectly well running engine.
If you look at the velocity and temp profiles as we have seen in CFD analysis of the Exhaust port/header you see that the temp varies dramatically
with not only position along the duct, but also across it profile.
I know that the very short probes as sold by some manufacturers for kart/bike use only intrude some 10 to 15mm into the header,and these read much lower than
if the tip is on the centerline.
So I try to standardize on 3X bore down the header and in the middle,using exposed tip probes from EGT industries - the only type that have a guarantee, 2 years for the Stinger type.
The exposed tip is way faster reacting and as long as the data sample rate is high enough ( above 10Hz ) you get to see what is actually happening in real time.
Some gauges only update the screen readout every couple of seconds - useless.

[karter444]

If you can only get to 500* then there is a serious problem.
It can only be a few issues that will cause this, way too much compression or timing for the fuel, or severe short circuiting.
I had the short circuiting problem on a 250 MX engine that had the Aux ground around to bore center.It ran just fine but when the piston was changed from a
Wossner to a Prox it ran like shit and would not respond to leaner jetting changes at all.
Finally in desperation I pulled it down ,to discover that the Wossner had a machined hole in the skirt above the small end that did not go around past the centerline.
The Prox had a huge cast in cutout,that was well past centerline and this was seriously joining the Aux and A transfer together as the piston passed over them.
Changing the piston fixed the jetting issue immediately,where previously it would run rich ( 500* ) no matter what jet was in it.
Any engine on petrol should be able to run past 600* in the header without any problems at all, no matter what the cc,rpm or bmep.

Hi Wobbly, when you say short circuiting do you mean exhaust gas entering the transfers or transfer outflow entering the exhaust
duct . with regard to the piston cutout it seems most pistons have some form of cutout that will link the Aport to the aux exhausts , why is this cutout there and why do some pistons have such different size cutouts . as you mentioned a cr 250 wossner has a relatively small cutout while a kx 250 pro x has a large cutout , both would join the A port and aux ex to some extent ,so I imagine some joining of these ports is acceptable
cheers Richard

[41juergen]

Presume you like the concept since you posted the picture?
If so, it makes me happy. I´m betting on the 72X72 config.

330856

Hey Rui, that's a nice head. Is that for your single cylinder bike and was that done by yourself or by Martin?

[wobbly]

If the Aux port is in front of the pin hole then no linking occurs,same with the skirt holes or pockets for weight reduction.
When linking does occur there must be transfer mixture entering the Ex as the egt drops,and going leaner does not fix this.

[breezy]

Husaberg thanks for links... had a go but the exhaust port bits a bit of a guess and the the near transfers also. seems to be some conflicting/ cant find dimensions, although thats probably me:facepalm:330867

[peewee]

330642
KTM200SX-EXC ’98-16
Ø Small End (A) 20.00mm
Ø Big End (B) 28.00mm
Center to Center (C)118.00mm
Width Small End (D)15.90mm
Width Big End (E 15.90mm
Total Length (F) 151.40mm
Eye to Eye Center (G) 94.00mm
Ø Big End Pin (H) 22.00mm
Length Big End Pin (I) 55.00mm
Washers 22 x 37 x 1.0mm
Remarks Barreled Rod

RD250 + RD350 Air Cooled -360-
Ø Small End (A) 20.00mm
Ø Big End (B) 28.00mm
Center to Center (C)110.00mm
Width Small End (D)16.00mm
Width Big End (E)16.00mm
Total Length (F) 141.50mm
Eye to Eye Center (G)86.mm
Ø Big End Pin (H) 22.00mm
Length Big End Pin (I) 50.75mm
Washers 22 x 37 x 1.0mm

RD400 ’76-79 -1A1/2T2-
Ø Small End (A)20.00mm
Ø Big End (B)28.00mm
Center to Center (C)115.00mm
Width Small End (D)16.00mm
Width Big End (E)16.00mm
Total Length (F) 147.00mm
Eye to Eye Center (G) 91.00mm
Ø Big End Pin (H) 22.00mm
Length Big End Pin (I) 51.00mm
Washers 22 x 37 x 1.0mm



I realized now why I used the Suzuki small end bearing. the ktm small ID is 20mm. banshee is 21mm. so to use the 16mm piston pin the bearing has to be substituted. seems like the Suzuki cage was wider or had wider rollers or something like that also, hence the reason I didn't use the ktm small bearing

[peewee]

Hi Wobbly, when you say short circuiting do you mean exhaust gas entering the transfers or transfer outflow entering the exhaust
duct . with regard to the piston cutout it seems most pistons have some form of cutout that will link the Aport to the aux exhausts , why is this cutout there and why do some pistons have such different size cutouts . as you mentioned a cr 250 wossner has a relatively small cutout while a kx 250 pro x has a large cutout , both would join the A port and aux ex to some extent ,so I imagine some joining of these ports is acceptable
cheers Richard

something like this doesn't link the exh direct to the transfer

[peewee]

Husaberg thanks for links... had a go but the exhaust port bits a bit of a guess and the the near transfers also. seems to be some conflicting/ cant find dimensions, although thats probably me:facepalm:330867

what about lifting the main exh floor a hair. jan has talked about it a lot of times. I lifted mine about 5mm (82mm stroke) although ill never know truly how well it works because I never had a previous dyno, but I don't think im losing any power. so if nothing else, the only thing ive lost is alittle time

[wobbly]

If the Aux ports are around to the centerline that piston will link them to the A port big time with such a deep pocket.

Re the RSA, it had the main Ex floor lifted by some 3mm from memory.

[jamathi]

If the Aux ports are around to the centerline that piston will link them to the A port big time with such a deep pocket.



I really do not understand why people make such idiotic pistons...

[trevor amos]

Wob, Frits, Jan?
In a typical cylinder reed 5 transfer port engine, having a Honda style ex-port, with a transfer port opening sequence of A then B then C would there be any overall net gain from having the B and C ports open simultaneously, where the C port lift gives more transfer port area and a touch more time /area. Or, would the overall balance of the transfer, in cylinder flow streams be compromised with just such a change leading to a reduction in performance? I can see both sides of this dilemma but not the more beneficial one, but I bet you guys can! Any advice is always appreciated by the greater readership.

cheers, Trevor

[Frits Overmars]

Wob, Frits, Jan? In a typical cylinder reed 5 transfer port engine, having a Honda style ex-port, with a transfer port opening sequence of A then B then C would there be any overall net gain from having the B and C ports open simultaneously, where the C port lift gives more transfer port area and a touch more time /area. Or, would the overall balance of the transfer, in cylinder flow streams be compromised with just such a change leading to a reduction in performance? I can see both sides of this dilemma but not the more beneficial one, but
I bet you guys can.As far as I'm concerned, you just lost that bet Trevor, because I have no way of knowing how that modification would influence the transfer balance.
Increased time.area is useless if it worsens short-circuiting. I'd need all data of all the transfer ducts before I could make an educated guess.

Having said that, even increased short-circuiting can have its merit. It drops the EGT, so the powerband may commence at a lower rpm value.
If you ever worked on a 100 cc direct-drive kart engine, you may remember the big single B-port, doing just that.

[Martin1981]

I really do not understand why people make such idiotic pistons...

Because they don`t know and don`t care about real high performance engines. It`s all about fast selling and making money....as usual.

[breezy]

If the Aux ports are around to the centerline that piston will link them to the A port big time with such a deep pocket.

Re the RSA, it had the main Ex floor lifted by some 3mm from memory.

i suspect the Aprilias non pocketed piston and wrist pin capping stopped this happening:sherlock:330875

i have been trying to make port map up from the " Aprilia files" posted way back to see what it looked like but wasn’t able to find all the info to do it and as such some of it was guess work.

Frits / Jan/ Wobbly are you able to show the aprilia rsa / rsw 125 port map? i have tried searching on the net, so as not to bother you, but have drawn a blank.:brick:

[Ocean1]

i suspect the Aprilias non pocketed piston and wrist pin capping stopped this happening:sherlock:330875

i have been trying to make port map up from the " Aprilia files" posted way back to see what it looked like but wasn’t able to find all the info to do it and as such some of it was guess work.

Frits / Jan/ Wobbly are you able to show the aprilia rsa / rsw 125 port map? i have tried searching on the net, so as not to bother you, but have drawn a blank.:brick:

From your dwg. Does this look close?

Only roughly to scale, and there's a port missing, (just too close to tangent and resolution too low).

[karter444]

As far as I'm concerned, you just lost that bet Trevor, because I have no way of knowing how that modification would influence the transfer balance.
Increased time.area is useless if it worsens short-circuiting. I'd need all data of all the transfer ducts before I could make an educated guess.

Having said that, even increased short-circuiting can have its merit. It drops the EGT, so the powerband may commence at a lower rpm value.
If you ever worked on a 100 cc direct-drive kart engine, you may remember the big single B-port, doing just that.

when you refer to short circuiting I assume you mean when the a port and ex port are open . That is piston heading to bdc . Where in the power curve do you think this problem would show up . I would have thought lower in the rev range as there would be more time for this to take place ?
cheers

[peewee]

If the Aux ports are around to the centerline that piston will link them to the A port big time with such a deep pocket.

Re the RSA, it had the main Ex floor lifted by some 3mm from memory.

yes of course but even if the cutout was farther rearward couldn't it still link to the void via the wristpin hole ? a oval located farther up may be a better idea

[peewee]

Because they don`t know and don`t care about real high performance engines. It`s all about fast selling and making money....as usual.

its simple. they never intend for the exh ports to be enlarged. so who cares where the cutout is

[wobbly]

Here are the sim inputs for RSA125, about as good as it gets.

[jamathi]

From your dwg. Does this look close?

Only roughly to scale, and there's a port missing, (just too close to tangent and resolution too low).

We never made port maps, sorry...
Only the distance from the top was measured.
And the chordal width, which is what really counts.
Using the circular 'feelers' shown in the picture.
They are attached to a piece of welding rod so you can bend them any way you want.
Very useful for measuring ducts and ports!

[chrisc]

Here are the sim inputs for RSA125, about as good as it gets.

Thank you Wobbly. Answers a few of my questions

[husaberg]

i suspect the Aprilias non pocketed piston and wrist pin capping stopped this happening:sherlock:330875

i have been trying to make port map up from the " Aprilia files" posted way back to see what it looked like but wasn’t able to find all the info to do it and as such some of it was guess work.

Frits / Jan/ Wobbly are you able to show the aprilia rsa / rsw 125 port map? i have tried searching on the net, so as not to bother you, but have drawn a blank.:brick:

Pretty sure those files have all the dimensions you would ever want to construct a port map.


its simple. they never intend for the exh ports to be enlarged. so who cares where the cutout is

Villiers and Hepolite must have been thinking ahead.:rolleyes::rolleyes:
330882
The pins about 3 inches too low though, plus the rings are brittle and only good for 7000rpm

[wobbly]

The drawings released by Frits years ago ( that are now all over the Interweb ) were very early iterations of the Aprilia, he did not want to be lynched the next time he ventured into Italy.
Here is the STA result from the late model RSA - and so before you wonder why Jans superb transfers are so far ahead of the Exhaust - ponder this.
The outflow Cd of the Exhaust is hugely influenced by the large radius that was machined onto the timing edge - the strictly theoretical Exhaust timing was around 79* ATDC, but the effective open time of
the duct top edge was closer to 82*.
Thus in reality the STA FLOW numbers match perfectly - remember this when dealing with crap transfer ducts, or Exhaust ducts that are WAY too big - ie most of them.

[dutchpower]

Can you show the inlet port Wobbly

[jamathi]

Hi Wobbly,

During 2003 our boss, you know him, designed a new exhaust., no 102.
It gave a lot more midrange, but killed revs, the engine stopped at 13000
So the radius of 2,5 was arrived at to recover max. revs....
With this radius also the midrange returned like it was before.
And so it stayed....

A couple of years later, after my DERBI interval, he was not there any more.
It was decided to compare the latest 6 exhaust pipes.
First they were all cleaned on the inside.
Which, by the way always cost some power, the power used to come back after a week of testing.
With these cleaned pipes the best carburation was determined for each pipe.
There proved to be quite some difference.
Then each pipe was tested with its best carburation.
The result was: nearly no difference.....
So much about pipe design and development, during some years, it is not easy!
Those tests were, of course, made with a radiused exhaust port.
Sometimes I still wonder what would have happened if we had insisted with an unradiused port.
And the older exhaust pipe!

[jamathi]

Refilling the damper and cleaning the pipe on the inside used to cost about 0,5-0,6HP
After a week of daily testing the normal HP returned.
At the races all the teams refilled their dampers and cleaned their exhausts before the race.
What do you think of this Wobbly?

[jonny quest]

Whst is meant by refilling damper?

[husaberg]

Whst is meant by refilling damper?

Repacking the exhaust Silencer.
http://www.xpsa.com.au/assets/alt_1/DEP-DEPMSS2.jpg
http://i.ebayimg.com/images/a/T2eC16F,!zQE9s3sqIw0BQmn,b0hS!~~/s-l300.jpg

[41juergen]

Here are the sim inputs for RSA125, about as good as it gets.

Thank's a lot Wob, would there be a chance also to get intake and carb data? :whistle:

[shnaggs]

Here are the sim inputs for RSA125, about as good as it gets.

Thanks for these Wobbly, but why is your exit roof angle 0.0? Is there a reason for this to be left at 0.0? I have found that changing this value does change the power quit at bit in the sim.

[breezy]

Thanks for all the information on this Aprilia port dimensions..:2thumbsup...

[jonny quest]

How much different was the jetting between pipe testing for brst optimization Jan? Are we talking needle tapers.... 1 to 2 mainjet sizes? All of the above plus more?

[TZ350]

Page 1730 links list to go here:- :yes:




A-ports timing 130°, roof angle 25°
B-ports timing 132°, roof angle 10°
C-port timing 132°, roof angle 50°
RSW and RSA ducts were the same.
Roof angles did not change since 1995
The RSA cylinder had improved cooling.


Re the RSA, it had the main Ex floor lifted by some 3mm from memory.


Here are the sim inputs for RSA125, about as good as it gets.

You will have to click back to the original post to see the sim data.


Here is the STA result from the late model RSA - and so before you wonder why Jans superb transfers are so far ahead of the Exhaust - ponder this.

The outflow Cd of the Exhaust is hugely influenced by the large radius that was machined onto the timing edge - the strictly theoretical Exhaust timing was around 79* ATDC, but the effective open time of the duct top edge was closer to 82*.

Thus in reality the STA FLOW numbers match perfectly - remember this when dealing with crap transfer ducts, or Exhaust ducts that are WAY too big - ie most of them.


Hi Wobbly,

During 2003 our boss, you know him, designed a new exhaust., no 102. 331059 It gave a lot more midrange, but killed revs, the engine stopped at 13000 So the radius of 2,5 was arrived at to recover max. revs.... With this radius also the midrange returned like it was before. And so it stayed....

A couple of years later, after my DERBI interval, he was not there any more. It was decided to compare the latest 6 exhaust pipes. First they were all cleaned on the inside. Which, by the way always cost some power, the power used to come back after a week of testing.

With these cleaned pipes the best carburation was determined for each pipe. There proved to be quite some difference. Then each pipe was tested with its best carburation. The result was: nearly no difference.....

So much about pipe design and development, during some years, it is not easy! Those tests were, of course, made with a radiused exhaust port. Sometimes I still wonder what would have happened if we had insisted with an unradiused port. And the older exhaust pipe!


Refilling the damper and cleaning the pipe on the inside used to cost about 0,5-0,6HP After a week of daily testing the normal HP returned.

At the races all the teams refilled their dampers and cleaned their exhausts before the race.
What do you think of this Wobbly?


Thanks for these Wobbly, but why is your exit roof angle 0.0? Is there a reason for this to be left at 0.0? I have found that changing this value does change the power quit at bit in the sim.


In general repacking the muffler will make a little extra power - but the Aprilia had a very short stinger, so maybe it liked the effective shorter length when the packing wasn’t tight around the perforated tube.

Its easy to understand why a " used " pipe made better power as this coats the inside surface and holds up the internal gas temperature.

Coating the inside with ceramic did the same thing, only way too much as it turned out in testing, as the engine lost all the bottom end power but picked up some top end.

Regarding the down angle of the Exhaust duct in the sim.
As I explained before the timing edge had a big radius on it, and thus the effective Cd was greater than the actual port area would dictate.

Using the down angle reduces the area by the cosine, so to get a better match to real flow conditions using zero gave a more accurate end result.

Here is the inlet input.


Here is the RV inlet inputs.

The Exhaust port itself was already made smaller, as Jan had begun experimenting with lifting the floor, but my comment about size was more directed at the duct exit area.

Simply using EngMod and shooting for a duct exit Mach of 0.8 the result is a huge jump in power when reducing the Aprilia flange area and creating a new transition within the spigot.

The duct length, including the spigot was also increased slightly to 2X bore and the pipe adjusted accordingly.


I remember Frits mentioning it's the best he had used, and also having seen it used here, which is why I'm specifically after Vinamold. There are alternatives however.

Here's a product called Composimold being used by a Thomas H who appears to cruise this forum, if not only the ESE thread. It's far more expensive though at $66NZD + $30 shipping for 20oz of the stuff -_-

http://bucketracing.blogspot.co.nz/2017/01/port-molds-with-composimold.html

https://4.bp.blogspot.com/-xXoJKt0qIGw/WI5B3c9h3zI/AAAAAAAAAfs/IW5qOcnbqg0ULUYPwarY6ArSSr65ZPM5wCLcB/s400/Port_Molds3.jpg


OK you blokes chasing Vinamould, here’s the stuff we use. For you kiwi types, it’s “cheap as chups” (:laugh::laugh::laugh::laugh:) around $100 for the 3 kg.

330857330858330859

Looked up your local contact:

Barnes NZ - Henderson, Auckland
B92-94 Railside Ave, Henderson, 0612 Auckland.
T: 09 973 1816
E: glen@barnesnz.co.nz



Google.co.uk came up with:

Vinamold - Best Value - - Direct from the manufacturer‎ (http://www.extruflexonline.co.uk/vinamold.html)

Ad<cite class="_WGk">www.extruflexonline.co.uk/vinamold</cite>‎
Large UK Vinamold Stocks, 24 Hr Delivery

4 hardness types?

I thought Vinamold was american.

[wobbly]

In general repacking the muffler will make a little extra power - but the Aprilia had a very short stinger, so maybe it liked the effective shorter length
when the packing wasnt tight around the perforated tube.
Its easy to understand why a " used " pipe made better power as this coats the inside surface and holds up the internal gas temperature.
Coating the inside with ceramic did the same thing, only way too much as it turned out in testing, as the engine lost all the bottom end power but picked up some top end.

Regarding the down angle of the Exhaust duct in the sim.
As I explained before the timing edge had a big radius on it, and thus the effective Cd was greater than the actual port area would dictate.
Using the down angle reduces the area by the cosine,so to get a better match to real flow conditions using zero gave a more accurate end result.

Here is the inlet input.

[41juergen]

In general repacking the muffler will make a little extra power - but the Aprilia had a very short stinger, so maybe it liked the effective shorter length
when the packing wasnt tight around the perforated tube.
Its easy to understand why a " used " pipe made better power as this coats the inside surface and holds up the internal gas temperature.
Coating the inside with ceramic did the same thing, only way too much as it turned out in testing, as the engine lost all the bottom end power but picked up some top end.

Regarding the down angle of the Exhaust duct in the sim.
As I explained before the timing edge had a big radius on it, and thus the effective Cd was greater than the actual port area would dictate.
Using the down angle reduces the area by the cosine,so to get a better match to real flow conditions using zero gave a more accurate end result.

Here is the inlet input.

Thank's a lot Wob, I was more referring to the inlet port with the RV (as I have absolute no experience with RV engines...:( )

[41juergen]

Hi Wobbly,

During 2003 our boss, you know him, designed a new exhaust., no 102.
It gave a lot more midrange, but killed revs, the engine stopped at 13000
So the radius of 2,5 was arrived at to recover max. revs....
With this radius also the midrange returned like it was before.
And so it stayed....

A couple of years later, after my DERBI interval, he was not there any more.
It was decided to compare the latest 6 exhaust pipes.
First they were all cleaned on the inside.
Which, by the way always cost some power, the power used to come back after a week of testing.
With these cleaned pipes the best carburation was determined for each pipe.
There proved to be quite some difference.
Then each pipe was tested with its best carburation.
The result was: nearly no difference.....
So much about pipe design and development, during some years, it is not easy!
Those tests were, of course, made with a radiused exhaust port.
Sometimes I still wonder what would have happened if we had insisted with an unradiused port.
And the older exhaust pipe!

Thank's a lot for all the insight Jan! In the drawing no rear cone nozzle / venturi is shown. Wasn't that in the design in that years or only not shown in the drawing?
cheers
Juergen

[husaberg]

Anyone know how these turned out?

330891


EMOT Racing 6 April 2016
AND THE OTHER SIDE HAS A CLOSED PINHOLE TOO..!!
How we did that will not be released yet.
For now we are looking for a few brave guys to test it.
We designed Kreidler and Ktm 50 pistons with the system.

[Norman]

Hi Wobbly,

During 2003 our boss, you know him, designed a new exhaust., no 102.
It gave a lot more midrange, but killed revs, the engine stopped at 13000
So the radius of 2,5 was arrived at to recover max. revs....
With this radius also the midrange returned like it was before.
And so it stayed....

A couple of years later, after my DERBI interval, he was not there any more.
It was decided to compare the latest 6 exhaust pipes.
First they were all cleaned on the inside.
Which, by the way always cost some power, the power used to come back after a week of testing.
With these cleaned pipes the best carburation was determined for each pipe.
There proved to be quite some difference.
Then each pipe was tested with its best carburation.
The result was: nearly no difference.....
So much about pipe design and development, during some years, it is not easy!
Those tests were, of course, made with a radiused exhaust port.
Sometimes I still wonder what would have happened if we had insisted with an unradiused port.
And the older exhaust pipe!


Jan, Wobbly, can I ask, should not the exhaust valve (which should be lowered?) eliminate/decrease the exhaust radius effect on the midrange? Thank you.

[husaberg]

We never made port maps, sorry...
Only the distance from the top was measured.
And the chordal width, which is what really counts.
Using the circular 'feelers' shown in the picture.
They are attached to a piece of welding rod so you can bend them any way you want.
Very useful for measuring ducts and ports!

Jan whats the paper stuffed in the cylinders for?
i noticed its also in the pic with the cylinder comparsions that (i think Riley Will) posted once.
330895
Edit It might have been Frits i can't recall.

[Frits Overmars]

Jan whats the paper stuffed in the cylinders for?That will be the chief mechanics' wish lists, accompanied by photographs of their daughters.

[husaberg]

That will be the chief mechanics' wish lists, accompanied by photographs of their daughters.

The wish list is always more power with less maintence.

[TZ350]

Ken Seebers sliding cylinder engine........... :2thumbsup

<div style="position:relative;height:0;padding-bottom:56.25%"><iframe src="https://www.youtube.com/embed/2p0dyPu7Gcs?ecver=2" width="640" height="360" frameborder="0" style="position:absolute;width:100%;height:100%;left:0" allowfullscreen></iframe></div>


<div style="position:relative;height:0;padding-bottom:56.25%"><iframe src="https://www.youtube.com/embed/dT4btNAmjz0?ecver=2" width="640" height="360" frameborder="0" style="position:absolute;width:100%;height:100%;left:0" allowfullscreen></iframe></div>



SLIDER UPDATE.


Finally got the thing running on the dyno frame. No load being applied by dyno, still got some software and hardware issues to be resolved. Main purpose was to see what falls off and even if it still works.


Not too much to say other than it makes some noise (apparently it could be heard over in kiwiland !!). Seems to zing with a bit of throttle, but then so does any 2 stroke really. Felt like 71 hp though.


Obviously the next thing is getting the dyno sussed.


<div style="position:relative;height:0;padding-bottom:56.25%"><iframe src="https://www.youtube.com/embed/PaYYIfLnHkA?ecver=2" width="640" height="360" frameborder="0" style="position:absolute;width:100%;height:100%;left:0" allowfullscreen></iframe></div>

[breezy]

We never made port maps, sorry...
Only the distance from the top was measured.
And the chordal width, which is what really counts.
Using the circular 'feelers' shown in the picture.
They are attached to a piece of welding rod so you can bend them any way you want.
Very useful for measuring ducts and ports!

Jan , with the auxilary exhaust ports being directly above the transfer ports did you think before arranging this set up that it would be power sapping with short cicuiting? also with the auxilary exhaust ports closing before the main exhaust port that fuel pulled into them would not be fully pushed back into the cylinder by the returning exhaust pulse again reducing power? Wobbly also mentioned that most exhaust ports are too large anyway , other than raising the exhaust port floor is there anything that you would have done to chase more power from that cylinder? :sherlock:

[wobbly]

Here is the RV inlet inputs.
The Exhaust port itself was already made smaller, as Jan had begun experementing with lifting the floor, but my comment about size was more directed at the duct exit area.
Simply using EngMod and shooting for a duct exit Mach of 0.8 the result is a huge jump in power when reducing the Aprilia flange area and creating a new transition within the spigot.
The duct length, including the spigot was also increased slightly to 2X bore and the pipe adjusted accordingly.

[jamathi]

How much different was the jetting between pipe testing for brst optimization Jan? Are we talking needle tapers.... 1 to 2 mainjet sizes? All of the above plus more?

Between 220 and 225 main jet size.

[jamathi]

Jan whats the paper stuffed in the cylinders for?
i noticed its also in the pic with the cylinder comparsions that (i think Riley Will) posted once.
330895
Edit It might have been Frits i can't recall.

The paper describes what has to be done with the cylinder, after inspection:
replate, hone, or fit a bronze ring after detonation.

[husaberg]

The paper describes what has to be done with the cylinder, after inspection:
replate, hone, or fit a bronze ring after detonation.

Cheers Jan
330940

[41juergen]

Here is the RV inlet inputs.
The Exhaust port itself was already made smaller, as Jan had begun experementing with lifting the floor, but my comment about size was more directed at the duct exit area.
Simply using EngMod and shooting for a duct exit Mach of 0.8 the result is a huge jump in power when reducing the Aprilia flange area and creating a new transition within the spigot.
The duct length, including the spigot was also increased slightly to 2X bore and the pipe adjusted accordingly.
Thank's a lot Wob for sharing...

[Makr]

Anyone know how these turned out?

330891



I want to see how they attached the two pieces.

[tedspeed230]

No.

Not depending on the bore, but on the stroke/bore-ratio.
330479

There is no difference in the porting of the late-model RSW and RSA cylinders.
But the RSA has better cooling (channels inside the inner curvatures of the transfer ducts) and two extra head studs that somehow contributed to power.
330480

Sorry if Iam missing the obvious but what is ATN in your scavenging angle concept?Using 54 bore works out for a and b ports but the c port comes out at 76 deg against a previously quoted 50 deg.
Thanks
Neil

[Frits Overmars]

what is ATN in your scavenging angle concept?Using 54 bore works out for a and b ports but the c port comes out at 76 deg against a previously quoted 50 deg.ATN is the standardized abbreviation of the inverse trigonometric function Arctangens:
https://en.wikipedia.org/wiki/Inverse_trigonometric_functions#arctan
Any pocket calculator worth its batteries should be able to help you on your way with it Neil.

[Flettner]

KTM 300, note the injector placement.

https://www.facebook.com/motostation/videos/10155289746293996/

YZ250

http://i1056.photobucket.com/albums/t380/uniflow/IMG_0868_zps6f424fcc.jpg

[teriks]

KTM 300, note the injector placement.

https://www.facebook.com/motostation/videos/10155289746293996/

Looks familiar :)

[Frits Overmars]

KTM 300, note the injector placement.They took a good look at your engine Neil :D.
330956330955

(click on the pics 3 times)

[husaberg]

They took a good look at your engine Neil :D.
330956330955

(click on the pics 3 times)

(Second pic) barbed brass pipe above reed valve?
i don't recall any mention of it being posilube,so is it a pressure sensor feed?
In the facebook video https://www.facebook.com/motostation/videos/10155289746293996/ it appears to go to the fuel tank, but that's presumably where the pump is located, so maybe rising rate regulator?
Flets fuel rail is far more snazzy as well

[Frits Overmars]

i don't recall any mention of it being posilubeIt is posilube. The pump is electric, the oil is contained in the frame top tube. http://adbmag.com.au/editorial/ktm-unveils-2018-fuel-injected-two-strokes/

[teriks]

(Second pic) barbed brass pipe above reed valve?
i don't recall any mention of it being posilube,so is it a pressure sensor feed?
In the facebook video https://www.facebook.com/motostation/videos/10155289746293996/ it appears to go to the fuel tank, but that's presumably where the pump is located, so maybe rising rate regulator?
Flets fuel rail is far more snazzy as well

My guess is that the oil line goes on the throttle body, and that the pipe on the cylinder is indeed a pressure senor feed.
330958

[tedspeed230]

ATN is the standardized abbreviation of the inverse trigonometric function Arctangens:
https://en.wikipedia.org/wiki/Inverse_trigonometric_functions#arctan
Any pocket calculator worth its batteries should be able to help you on your way with it Neil.

Thank you Frits its all clear now.

[Juho_]

Hello,

I've been developing a Minarelli Am6 engine for 'some time' now.. and currently it has +5mm stroke (44mm, bore 39,90mm) = 55cm3.

On previous cylinder I reached less power, but higher peak bhp rpm (around 13-13,500rpm) and about 14,800rpm max rpm with E85 fuel and with and without heat wrap on exhaust pipe.

The differences to the current cylinder / motor are cylinder capacity, port timings (only slightly, but way more blowdown and transfer port area, and much, much better transfer ducts), larger crankcase volume (now at 305cc @ TDC including transfer ducts - I have understood, that the transfer ducts usually are not included in crankcase volume..haven't measured them yet) , exhaust duct and adapter to pipe, which are a lot smaller (the adapter also shorter .. yes, I know, not good, makes the exhaust duct also shorter...which is approx. 50mm, and it was ~75mm...sadly I do not remember, what was the previous adapter and exhaust duct diamete or areas..but do remember that, they were much larger)

The question is, what I have been thinking.. could the exhaust duct / adapter be too small because of it's reduced size and cause the much lower peak bhp rpm, which is currently at around 11,000-12,000rpm.. when adjusted very lean at high rpm - it's at ~12,000rpm.
On rich side it may go even below 11,000rpm.. fuel change did not effect, like it has previously done -- neither did retarding ignition timing (I do not have an EGT meter).

I'm asking your opinion, because I ran out of argon, so I'm not able to TIG weld a new adapter and do more modifications for the cylinder.

Pipe is indeed way too long for the engine (830mm including exhaust duct length). But it does not explain the difference.
(yes, I'm going to fabricate a shorter pipe, when I have time and argon)


And sorry for my bad english ! I hope you understand, what I mean.
Thanks in advance !

[breezy]

KTM 300, note the injector placement.

https://www.facebook.com/motostation/videos/10155289746293996/

YZ250

http://i1056.photobucket.com/albums/t380/uniflow/IMG_0868_zps6f424fcc.jpg

Bet you cant wait for the royalties to start flooding in:lol::brick:

[wobbly]

There is something very wrong about the case volume in the AM6.
If its 305cc at TDC then the case ratio is 1.22 - that is HUGE ie it cant be right, or if it is then you will never be able to get it tuned correctly.
And the transfer ducts are ALWAYS included in the calculation of the total case volume at TDC.
E85 will react alot like Methanol in that a rich mixture wont loose power anything like petrol will, but of course it cools the pipe temp
alot more.

[Nath88]

My guess is that the oil line goes on the throttle body, and that the pipe on the cylinder is indeed a pressure senor feed.
330958

Confirmed here.
https://www.motopuls.com/images/Zeljko/KTM-EXC-2018.jpg

Oil pump looks like the same as the Aprilia ditech.

I wish I had the smarts/time to write 2 stroke specific firmware for my ecu. Oil pump output would be awesome.

[husaberg]

It is posilube. The pump is electric, the oil is contained in the frame top tube. http://adbmag.com.au/editorial/ktm-unveils-2018-fuel-injected-two-strokes/


My guess is that the oil line goes on the throttle body, and that the pipe on the cylinder is indeed a pressure senor feed.
330958

http://dirtbiketest.com/fresh-dirt/ktms-fuel-injected-two-stroke-here-it-is/#dWDvutkrrbkFy6Ob.97

KTM have patents so i guess we can search to see what their and Mikunis are in relation to it.
I guess if people ran vastly different petrol/oil mixture rates that the fuel injection might get a bit befuddled.
So the oil injection might be a work arround that.
I do hope the fuel injection is not as prone to low speed flame outs as the Four stroke equivilents are.

[Juho_]

Thanks for the reply, wobbly !

Yes, the case volume may not be correct because of the way it was measured.
First the case was filled with cylinder attached without piston (yes, crankshaft and reed valve were also attached), then just se cylinder with piston fitted in TDC position with pin and needle bearing and filled with oil.

The case was filled untill the oil started reaching transfer ducts.

This way the connecting rod's volume is not included (so already at this point is not a true volume).
But I did not have many options..best would have been a drilled piston.

I got the 'idea' of too small exhaust duct / exhaust adapter, because the engine did not react any modifications like it previously did (higher peak bhp rpm).
The adapter is only 21,50mm ID..previous was something like 23....25mm.

[Flettner]

http://dirtbiketest.com/fresh-dirt/ktms-fuel-injected-two-stroke-here-it-is/#dWDvutkrrbkFy6Ob.97

I do hope the fuel injection is not as prone to low speed flame outs as the Four stroke equivilents are.

No, they don't.

[husaberg]

No, they don't.

I had a look for a Patent for KTM and i couldn't find it, but here a a few that stould out some are transfer injection other are intersting.
Interstingly IHI (as in the baby turbos the CX500 had as well as the Kei class cars)has a heck of a lot for uniflow two strokes.

 Fuel injection system for a two-stroke engine
Publication number: 20020011223
Abstract: An internal combustion, two stroke engine is disclosed. The engine includes a crankcase with a cylinder adapted to house a piston. At least one transfer duct communicates the crankcase to the cylinder. At least one fuel injector is disposed through a wall of the transfer duct. The fuel injector is positioned to inject fuel tangentially to the cylinder.
Type: Application
Filed: July 18, 2001
Publication date: January 31, 2002
Inventors: Gunter Zauner, Michael Seyrl

 Control system and method and engine control unit for internal combustion engine
Publication number: 20020020386
Abstract: There are provided a control system and method and an engine control unit for an internal combustion engine, which are capable of properly determining an amount of fuel to be injected during a two-stage fuel injection combustion mode and a duration period of this mode such that stable combustion and smooth transition between combustion modes are ensured, thereby attaining excellent drivability and fuel economy. The combustion mode of the engine is switched between a homogeneous combustion mode in which fuel injection into each cylinder is performed during an intake stroke, a stratified combustion mode in which the fuel injection into the cylinder is performed during a compression stroke, and the two-stage fuel injection combustion mode in which the fuel injection into the cylinder is performed once during the intake stroke and once during the compression stroke during transition between the homogeneous combustion mode and the stratified combustion mode.
Type: Application
Filed: August 10, 2001
Publication date: February 21, 2002
Applicant: Honda Giken Kogyo Kabushiki Kaisha
Inventors: Ken Ogawa, Toru Kimura, Yutaka Kohda, Kazuhiro Ueda

 Fuel injection system for a two-stroke engine
Patent number: 6691649
Abstract: An internal combustion, two stroke engine is disclosed. The engine includes a crankcase with a cylinder adapted to house a piston. At least one transfer duct communicates the crankcase to the cylinder. At least one fuel injector is disposed through a wall of the transfer duct. The fuel injector is positioned to inject fuel tangentially to the cylinder.
Type: Grant
Filed: July 18, 2001
Date of Patent: February 17, 2004
Assignee: Bombardier-Rotax GmbH
Inventors: Günter Zauner, Michael Seyrl

 Temperature-controlled fuel injection system for two-stroke engines
Publication number: 20060016434
Abstract: The present invention provides a system and method for controlling a two-stroke engine in correspondence with exhaust gas temperature. An engine control unit (ECU) receives an output from a temperature sensor mounted in the exhaust pipe. The engine control unit controls the operation of a fuel injector in fluid communication with the intake port of the engine in correspondence with the output from the temperature sensor. In one embodiment, correspondence is achieved by determining fuel injection parameters based on a plurality of maps, each corresponding to a different temperature range. The ECU references the map corresponding to the sensed temperature of the exhaust gas. Fuel injection parameters may include injection timing and the amount of fuel injected.
Type: Application
Filed: July 20, 2005
Publication date: January 26, 2006
Inventors: Daniel Johnson, Kim Chervestad, Greg Spaulding

 Temperature-controlled fuel injection system for two-stroke engines
Patent number: 7258107
Abstract: The present invention provides a system and method for controlling a two-stroke engine in correspondence with exhaust gas temperature. An engine control unit (ECU) receives an output from a temperature sensor mounted in the exhaust pipe. The engine control unit controls the operation of a fuel injector in fluid communication with the intake port of the engine in correspondence with the output from the temperature sensor. In one embodiment, correspondence is achieved by determining fuel injection parameters based on a plurality of maps, each corresponding to a different temperature range. The ECU references the map corresponding to the sensed temperature of the exhaust gas. Fuel injection parameters may include injection timing and the amount of fuel injected.
Type: Grant
Filed: July 20, 2005
Date of Patent: August 21, 2007
Assignee: Arctic Cat Inc.
Inventors: Daniel J. Johnson, Kim Chervestad, Greg Spaulding

 TWO-STROKE ENGINE WITH FUEL INJECTION
Publication number: 20150184574
Abstract: In a two-stroke engine including a scavenging port (43b) having an open end (42d) opening out in a side wall of the cylinder bore (3a) and communicating with a crank chamber (2a), the open end being configured to be closed and opened by the piston (22), a fuel injection device (71) is mounted on the engine main body so as to inject fuel onto a back side of the piston and/or a part of the side wall of the cylinder bore located under the piston via the open end of the scavenging port or via the open lower end of the cylinder bore. The fuel deposited on the surfaces of the piston and the cylinder inner wall promotes the cooling of such parts.
Type: Application
Filed: October 15, 2014
Publication date: July 2, 2015
Applicant: HONDA MOTOR CO., LTD.
Inventors: Yoshikazu Yamada, Mashu Kurata

Direct injection two stroke engine combustion mapping
 Patent number: 6505600
Abstract: A control unit is provided for an internal combustion engine including an engine block comprising a plurality of cylinders operable in a homogenous combustion mode and a stratified combustion mode in response to an engine throttle position. The control unit is programmed to switch the engine cylinders to the homogenous combustion mode at a throttle position of greater than about 20% of wide open throttle. As such, the combustion mode is switched form the stratified combustion mode to the homogenous combustion mode at a higher throttle opening that more capably supports increased fuel injection quantities of homogenous combustion in the engine cylinders. Problematic conditions of conventional pontoon boat systems due to switching of engine cylinders to homogenous combustion at high RPMs and restricted throttle openings is therefore avoided.
Type: Grant
Filed: November 6, 2000
Date of Patent: January 14, 2003
Assignee: Bombardier Motor Corporation of America
Inventor: Patrick C. Tetzlaff

 ENGINE START CONTROL SYSTEM AND METHOD
Publication number: 20100250105
Abstract: A 720-degree motor stage storage means for holding the result of stroke discrimination for the engine E also in the period for carrying out an idle stop control is provided. At the time of restarting the engine E from an idle stop state, a new stroke discriminating processing is not conducted, but the result of stroke discrimination stored in the 720-degree motor stage storage means is used, to thereby drive a fuel injection system and an ignition device. A stage decision unit for allocating a period of two revolutions of a crankshaft to 720-degree motor stages based on the result of stroke discrimination, a fuel injection and ignition stage correlation table having predetermined correlations of 720-degree motor stages with fuel injection stages and ignition stages, and restarting time motor stage conversion means for conversion of a 720-degree motor stage into a fuel injection stage and an ignition stage, are provided.
Type: Application
Filed: March 10, 2010
Publication date: September 30, 2010
Applicant: HONDA MOTOR CO., LTD.
Inventors: Toshiya NAGATSUYU, Toshifumi OSAWA, Katsuhiro UTSUGI

 TWO-STROKE INTERNAL COMBUSTION ENGINE
Publication number: 20120024275
Abstract: A two stroke crank case scavenged two-stroke internal combustion engine, the engine including: a cylinder (2) configured to reciprocatingly receive a piston (6) therein defining a combustion chamber (8), the combustion chamber comprising an ignition means (5) for igniting an air/fuel mixture and an exhaust port (40) for evacuating the exhaust fumes, a crank case (3) including a crank shaft (18), an indirect fuel supply system (4), such as a carburettor (12) or a low pressure fuel-injection system, for supplying fuel to the crank case (3) to be scavenged to the combustion chamber (8), at least one transfer duct (20, 20?) each extending from the crank case (3) to at least one corresponding transfer port (21, 21?) for connecting to the combustion chamber (8), additional air filling means (25, 24, 27, 23, 23?, 22, 22?,26, 26?) for at least partly filling the transfer duct/s (20, 20?) with additional air from the transfer port (21, 21?) towards the crank case (3), and a direct injection means (7) for injecting fue
Type: Application
Filed: March 31, 2009
Publication date: February 2, 2012
Applicant: HUSQVARNA AB
Inventors: Joel Berneklev, Mikael Bergman

 Two-stroke engine and method for operating the same
Publication number: 20030209214
Abstract: A two-stroke engine (1) for a work apparatus includes a combustion chamber (3) configured in a cylinder (2). The engine includes a piston (5, 21) which drives a crankshaft (7) via a connecting rod (6). The crankshaft (7) is rotatably journalled in a crankcase (4). The two-stroke engine (1) includes at least three transfer channels (10, 11, 20) which connect the combustion chamber (3) to the crankcase (4) at pregiven control times. At pregiven control times, fuel is injected in the region of a transfer channel (10, 11, 20). A first component quantity of the fuel is transfer synchronously injected into the channel and a second component quantity from a preceding injecting cycle exits from the crankcase (4) into the combustion chamber (3). For this purpose, an injection nozzle (19) is mounted in at least one transfer channel (10). The injection nozzle (19) injects fuel into the transfer channel (10) open to the cylinder (2).
Type: Application
Filed: May 8, 2003
Publication date: November 13, 2003
Inventor: Heiko Rosskamp

 Stratified air scavenging in two-stroke engine
Patent number: 4995349
Abstract: A two-cycle engine has an air inlet in the crankcase, and a spiral air-fuel passage encircling the cylinder wall rising from the crankcase to an inlet in the cylinder head to effect cooling of the cylinder. A fuel injection device introduces fuel into the transfer passage. A unidirectional valve admits air and fuel into the cylinder head and curved fins impart a swirling action to the air and fuel to effect a fuel and air stratification. An exhaust passage in the cylinder wall has an adjustable throttle to control dirctly the outflow of exhaust gases and indirectly the inflow of fresh fuel-air mixture, whereby the power level of the engine is controlled.
Type: Grant
Filed: August 7, 1989
Date of Patent: February 26, 1991
Assignee: Walbro Corporation
Inventor: Charles H. Tuckey

 Two-stroke internal combustion engine
Patent number: 8677954
Abstract: A two stroke crank case scavenged two-stroke internal combustion engine, the engine including: —a cylinder (2) configured to reciprocatingly receive a piston (6) therein defining a combustion chamber (8), the combustion chamber comprising an ignition means (5) for igniting an air/fuel mixture and an exhaust port (40) for evacuating the exhaust fumes, —a crank case (3) including a crank shaft (18), —an indirect fuel supply system (4), such as a carburettor (12) or a low pressure fuel-injection system, for supplying fuel to the crank case (3) to be scavenged to the combustion chamber (8), —at least one transfer duct (20, 20?) each extending from the crank case (3) to at least one corresponding transfer port (21, 21?) for connecting to the combustion chamber (8), —additional air filling means (25, 24, 27, 23, 23?, 22, 22?,26, 26?) for at least partly filling the transfer duct/s (20, 20?) with additional air from the transfer port (21, 21?) towards the crank case (3), —and a direct injection means (7) for injecti
Type: Grant
Filed: March 31, 2009
Date of Patent: March 25, 2014
Assignee: Husqvarna AB
Inventors: Joel Berneklev, Mikael Bergman

 Two-stroke engine and method for operating the same
Patent number: 6851402
Abstract: A two-stroke engine (1) for a work apparatus includes a combustion chamber (3) configured in a cylinder (2). The engine includes a piston (5, 21) which drives a crankshaft (7) via a connecting rod (6). The crankshaft (7) is rotatably journalled in a crankcase (4). The two-stroke engine (1) includes at least three transfer channels (10, 11, 20) which connect the combustion chamber (3) to the crankcase (4) at pregiven control times. At pregiven control times, fuel is injected in the region of a transfer channel (10, 11, 20). A first component quantity of the fuel is transfer synchronously injected into the channel and a second component quantity from a preceding injecting cycle exits from the crankcase (4) into the combustion chamber (3). For this purpose, an injection nozzle (19) is mounted in at least one transfer channel (10). The injection nozzle (19) injects fuel into the transfer channel (10) open to the cylinder (2).
Type: Grant
Filed: May 8, 2003
Date of Patent: February 8, 2005
Assignee: Andreas Stihl AG & Co. KG
Inventor: Heiko Rosskamp

 Valveless two-stroke-cycle oscillating engine
Patent number: 5228414
Abstract: A two-stroke-cycle engine has a pivoted divider oscillating within a fan-shaped combustion volume. The divider is connected to a connecting rod which is connected to an output crankshaft. Seals are used instead of piston rings. Each of the two radial walls has a spark plug and a fuel injection tube located near the outer end. Each planar parallel side wall has an air inlet port near the inner end. An exhaust port is located in the center of the arcuate wall.
Type: Grant
Filed: September 10, 1992
Date of Patent: July 20, 1993
Assignee: Robert D. Hall
Inventor: Jimmye Crawford

 Two-stroke engine and method of operating the same
Patent number: 6899067
Abstract: A two-stroke engine, especially for a portable handheld work apparatus, includes a combustion chamber configured in a cylinder. The combustion chamber is delimited by a piston which moves upwardly and downwardly. Combustion air is supplied to the engine via an air channel. The air channel opens with an air channel window into the cylinder. The crankcase of the two-stroke engine is connected at pregiven piston positions to the combustion chamber via transfer channels. The transfer channels open with inlet windows into the cylinder. An injection nozzle opens into at least one transfer channel. In the region of top dead center of the piston, the air channel is connected via a piston window to a transfer channel. An injection nozzle is arranged in the transfer channel and injects fuel into the transfer channel during the induction of combustion air into the crankcase.
Type: Grant
Filed: June 17, 2003
Date of Patent: May 31, 2005
Assignee: Andreas Stihl AG & Co. KG
Inventors: Heiko Rosskamp, Christian Puchas

 Engine brake system of a two-cycle engine for a motor vehicle
Patent number: 4941441
Abstract: A two-stroke engine has a scavenge pump provided in an intake passage, a bypass around the scavenge pump and a fuel injector provided for injecting fuel in a cylinder of the engine. A valve is provided in the bypass so as to close the bypass. When deceleration of a vehicle is detected, the valve is closed and the fuel injection from the fuel injector is stopped.
Type: Grant
Filed: August 18, 1989
Date of Patent: July 17, 1990
Assignee: Fuji Jukogyo Kabushiki Kaisha
Inventor: Hideo Watanabe

 Two-stroke, homogeneous charge, spark-ignition engine
Publication number: 20090056687
Abstract: A method for combusting fuel in an engine involving decreasing a first volume of air to a third volume, in two stages, the first stage in a crankcase compressor decreasing a first volume of air to a second volume and a second stage in the engine cylinder decreasing a second volume of a gas to a third volume, injection of fuel between the two stages into partially compressed hot air to provide homogenous charge to the cylinder to begin second stage compression in the cylinder having two variable compression ratios, a first variable compression ratio for low loads to reach a compression temperature slightly below the autoignition temperature of the homogeneous charge such that spark ignited HCCI-like combustion being emission free, a second much smaller variable compression ratio for preventing pre-ignition at high loads, then increasing the pressure at constant volume via combusting homogeneous charge in the cylinder, increasing the third volume of gas to a fourth volume (an expansion process having a chosen e
Type: Application
Filed: August 28, 2007
Publication date: March 5, 2009
Inventor: Pao C. Pien

[Frits Overmars]

the case volume may not be correct because of the way it was measured.... But I did not have many options..best would have been a drilled piston.
I got the 'idea' of too small exhaust duct / exhaust adapter, because the engine did not react any modifications like it previously did (higher peak bhp rpm). The adapter is only 21,50mm ID..previous was something like 23....25mm.Juho, one problem may solve the other: that 21,5 mm adapter may provide you with a holed piston :devil2:.
25 mm should be about the right adapter size.


Temperature-controlled fuel injection system for two-stroke engines
Patent number: 7258107
Abstract: The present invention provides a system and method for controlling a two-stroke engine in correspondence with exhaust gas temperature. Great thinking: if the EGT drops, you can correct it by leaning the fuel-air mixture.
Generally this will work. There's just one snag. When detonation sets in, the EGT will drop, so the Engine Control Unit will lean the mixture, stimulating more detonation. Don't try this at home.

[husaberg]

Great thinking: if the EGT drops, you can correct it by leaning the fuel-air mixture.
Generally this will work. There's just one snag. When detonation sets in, the EGT will drop, so the Engine Control Unit will lean the mixture, stimulating more detonation. Don't try this at home.

Aimed more at low bmep more non comp engines me thinks.
What did you think of this. (Very Honda)

ENGINE START CONTROL SYSTEM AND METHOD
Publication number: 20100250105

[shnaggs]

Great thinking: if the EGT drops, you can correct it by leaning the fuel-air mixture.
Generally this will work. There's just one snag. When detonation sets in, the EGT will drop, so the Engine Control Unit will lean the mixture, stimulating more detonation. Don't try this at home.

I believe this is what the E-TEC snow mobiles do, but they have a knock sensor to detect detonation.

[casal-fan]

Hey Rui, that's a nice head. Is that for your single cylinder bike and was that done by yourself or by Martin?

Hi Juergen.
Jeah... I also like it a lot, turned out great. Martin sculptured it for me after we agreed on the design, ccs, etc.
Have you noticed it protrudes into th cyl. just like Jan spoke about a few pages ago?

And about the short circuiting caused by strangely designed piston that also came up a few pages ago.
Also encountered this problem with the Gasgas piston.
Decision was made not to open aux. exhaust pass the holed piston sides.
Engmod showed enough TA with 193* exh. duration. 72X72 are relatively big numbers, around 9500 rpm at max power with good overrev was the goal.

[Frits Overmars]

What did you think of this. (Very Honda)
ENGINE START CONTROL SYSTEM AND METHOD
Publication number: 20100250105Very Honda indeed. Who else would write "720-degree motor" instead of 'foul-stroke'. Swankers! (you may omit the S if you so desire).
My first thought while reading it was 'hit or miss', soon followed by 'hit and miss' :devil2:.

[Juho_]

Juho, one problem may solve the other: that 21,5 mm adapter may provide you with a holed piston :devil2:.
25 mm should be about the right adapter size..
Alright, thank you !

The engine seems to not detonate, knock or blow up easily. Not sure why, but it has been ran on very high compression, extremely lean conditions.. but never overheated (water temp won't get over 60C -- not sure how it would change on dyno).

I forgot to mention one important problem: the piston.
It has 2 thick (1,20mm) rings and slots above piston pin (which connect aux exhaust ports and main transfer ports) !
I'm sure it will cause some problems..and power loss.

And yes, it's only a temporary solution, because previous single ring piston was worn out (piston ring end gap 0,70mm and piston-to-cylinder wall clearance more than 0,07mm)

[wobbly]

That then is the problem with the AM6.
If you have holes in the skirt above the small end that connect the Aux and the A transfer,then it will run rich,and will not respond at all
to jet changes.
The seemingly rich mixture in the Exhaust is caused by the short circuiting, not by rich jetting, so you go leaner and nothing happens.

A file I have of a fully tuned TZR50 that puts out 18Hp Crank at 13,000 with triple Exhaust ports and this has a spigot exit area equivalent to 22mm.
This is 78% of the Exhaust effective area, and gives a Mach of 0.8 , absolutely fine.
Going slightly bigger in displacement or making more power than this would put the exit velocity close to sonic, so yes this may well be an issue as well.

The case com ratio is a very important element, guessing or not measuring it correctly isnt an option.
PS - you have a worn out piston available, drill a hole in it.

[DoldGuy]

Hi Juergen.
Jeah... I also like it a lot, turned out great. Martin sculptured it for me after we agreed on the design, ccs, etc.
Have you noticed it protrudes into th cyl. just like Jan spoke about a few pages ago?

And about the short circuiting caused by strangely designed piston that also came up a few pages ago.
Also encountered this problem with the Gasgas piston.
Decision was made not to open aux. exhaust pass the holed piston sides.
Engmod showed enough TA with 193* exh. duration. 72X72 are relatively big numbers, around 9500 rpm at max power with good overrev was the goal.

Casal-Fan,

Take a look at the KTM 300 piston, 18mm pin, 38mm compression Height(same as the GasGas), ring pins set at the 6:00 position. The cutout should not expose the exhaust/transfers on the cylinder pictured (GasGas EC300?)

Interested to hear more about your build/setup.

[TZ350]

330964

Back as far as 2013 ThumperTalk was talking about a German mag that had shown a picture of a YZ250 cylinder with Fuel Injectors and were speculating that Yamaha were about to bring out a fuel injected YZ250 anytime soon.

They were wrong.

Neil Hintz had previously successfully fitted fuel injection to a Kawasaki 350 Bighorn.

https://youtu.be/ifSEql1X4R0 and https://youtu.be/eleqBGvOM4M

And the cylinder pictured by ThumperTalk is actually the one that Neil Hintz and Wayne Blackwood fitted to Wayne's bike.

https://youtu.be/UEQli7nuak4 and https://youtu.be/1YG9ko8-Nwk

330965

The latest new KTM has fuel injectors in the self same position as Neil and Wayne did 5 years ago.

https://www.facebook.com/motostation/videos/10155289746293996/

Neil Hintz on FaceBook.

Injectors, same ports, same position!

You would have to say that KTM must have looked at the video of Wayne Blackwoods YZ250 that we set up on EFI. It looks identical but no drum valve throttle. I guess they will bring that out in a future model.

I'd had quite a conversation with a KTM representive a few years ago, about the time we got the YZ going.

He told me KTM would use something far more sophisticated than we had set up. Most probably Direct injection, he was wrong. Delayed TIP is clearly the way to go. I must give that rep a ring and rub it in.

Looks to me like Neil and Wayne successfully did big bore 2T EFI first. And certainly they were the first to be riding around at competitive events with them.

[koenich]

just found the attached pictures on instagram...interesting

330973 330974

[Frits Overmars]

330976
Ktm persevered experimenting with the Orbital DI-system for quite some time despite the fact that it "did not perform well and sounded terrible".
About that same time some Orbital engineers visited Aprilia driving a Ford Fiesta with an Orbital two-stroke triple engine (derived from a Suzuki outboard).
The engine performed very well but it sounded as if it was in dire need of valve clearance adjustment.
Culprits were the big valves that admitted air to the combustion chambers. You could hear them rattle and their mass limited maximum rpm.

330975 330977
The injector layout of the middle KTM unit strongly reminds me of the Bimota V-due. It was called the V-didn't for a reason....

[TZ350]

Looks like KTM tried to do something more sophisticated like they told Neil Hints that they would. But eventually they found that the Kiwis already had a handle on it and KTM copied what was tried and true and already working properly in New Zealand.

[husaberg]

330976

The injector layout of the middle KTM unit strongly reminds me of the Bimota V-due. It was called the V-didn't for a reason....

Did you read the stuff i posted about what tthe crowd in i think Texas had done with the V due
They identified it was a problem of a combination of poor seals and porus crankcase castings in combination to a last minute change to a less far sophisicated injector that were the main reason the bimota was erratic in running

It sounded very plausable, considering some of the bikes reponded to the updated softwear mapping, while some just refused to ever run correctly at all.


Bob Steinbugler of specialists Bimota Spirit in North Carolina says that, while switching to carbs solved some problems, the V-Due’s bigger issue was the crankcase seals.
“These seals were too small and not up to the task of sealing the crankshafts,” Steinbugler explains. “They would allow small amounts of air to be sucked past them, and that phenomenon in a two-stroke changes the mixture. The amount of air varied over time and from V-Due to V-Due, so it couldn’t be tuned out.
“For the Trofeo series, Bimota changed from fuel injection to carburettors initially and nothing really improved. Upon further observation they discovered the crankcase seal problem. This was a difficult problem to solve because there was not enough material in the crankcase castings to machine a pocket for a larger outside diameter seal to fit the crankshaft and seal it better. They used a seal that was the same outside diameter and had a smaller inside diameter, but to do this they had to machine down the ends of the crankshafts. This then led to some crankshaft failures.

“The main investment that Piero Caronni made was to go back to the foundry and have crankcases re-cast with a new design that added some material around the crankshaft holes to accept better seals. Once this was done, the bikes became predictable and consistent. The fuel-injection system still suffered from lack of development time – the original prototypes used fuel-injectors supplied by Ferrari and were precise in the range that the V-Due required. For the production versions these were not available, so they went to a production injector and these were not precise enough at the low volume end and did not have enough mapping development to sort them out really well.

[ken seeber]

WHAT ELSE CAN WE SAY:-----------------------:woohoo:

330978

[Frits Overmars]

330978The last thing I'd want to do is to turn this forum into a Facebook-clone, but sometimes it would be nice to have a 'Like'-button. Like right now :niceone:.

[Peter1962]

The last thing I'd want to do is to turn this forum into a Facebook-clone, but sometimes it would be nice to have a 'Like'-button. Like right now :niceone:.

I think that Stefan Pierer at least should invite Flettner to austria and not only to eat Wiener Schnitzel or Schweinsbraten, and Apfelstrudel for desert, but to thank him for the inspiration that he gave the KTM engineers who were silently lurking the kiwibiker forum :yes:

If Pierer is a clever guy, he will offer Flettner a 300 cc injected bike for free, for development work and ask him kindly if he would be prepared to check the quality of work that his copycat engineers produced. And maybe thow in some budget to buy some nice trousers.

[Haufen]

The last thing I'd want to do is to turn this forum into a Facebook-clone, but sometimes it would be nice to have a 'Like'-button. Like right now :niceone:.

There is one, right next to the "blog this post" below each post.
Let's hope Neil does not make it too hard for other OEMs to keep up with his current project.

[TZ350]

I would very much like to see modern engine management and EFI applied to 2T's.

Orbital

From Timothy Carl Hickox – Experimental Motorcycle Association.

It has been more than 30 years since Orbital introduced their Direct Fuel Injection system. It is still in production. It has proven to be reliable and to provide fuel consumption and exhaust emissions better than a four-stroke engine (of equal performance). (I refer here to engines, not to tailpipe emissions, which depend on catalysis.) Their design used compressed air to inject a dense air/fuel mixture at the cylinder head. A few years later, we had another option: E-TEC. This originated with Markus Ficht, in Spannleitenberg, Germany.

He invented a different system to use on the two-stroke engines that he was building. (Ficht was an innovator; I wish we knew more about him and his work.) Outboard Marine Corporation saw the potential and bought his company to acquire the patent on the injector. Why they decided to go this independent route, rather than use Orbital’s technology, is unclear. Maybe they didn’t want to pay royalties to Orbital, or maybe they just wanted complete control over the adaptation and evolution of the system. The Ficht system made use of a hydraulic hammer.

The line pressure was low, maybe 50-psi. A small quantity of fuel was then “hammered” by an accelerated piston that compressed the fuel up to about 1000-psi, at which pressure it entered the cylinder. This is called a solid-injection system (i.e. no air). After much development, the Ficht injectors went into production, but some problems were still unresolved. A second phase of development made the system trouble free, and OMC changed the name from “Ficht” to “E-TEC”.

One advantage of E-TEC over Orbital is that the former does not require a battery for starting. Decades of use have proven the efficacy and efficiency of these two direct-injection systems. The marine engines that use these must meet both air- and water-pollution standards – and the space limitations on outboards do not permit the use of catalysis to clean up a dirty engine. I go over all this history in order to explain that two-stroke engines could have been and can be used in road-going motorcycles anytime a manufacturer wants to adopt the available technology (or develop something of comparable performance). That no one is doing so does not mean that some unapproachable technology is needed.

[F5 Dave]

I presume marine applications usually means lots of constant state throttle and in my ignorance presumably throttle response can be lethargic with little penalty as there has to be lag getting the water to comply . Whether these systems are masked in this environment? I don't know.

[jasonu]

Looks like KTM tried to do something more sophisticated like they told Neil Hints that they wanted to do. But eventually they found that the Kiwis already had a handle on it and KTM copied what was tried and true and already working properly in New Zealand.

Not bad for a country with only 4 million people.....

[SwePatrick]

My buttugly racer has met some development in the looks ;)
A couple of heatcyckles more and i´ll se what it produces on the dyno.
Everythings new in the engine.
Bearings,crank,cylinder,piston.
I have ported the cylinder som more also.
Switch to methanol has been done.

It has been started since the pic was taken

https://scontent.xx.fbcdn.net/v/t31.0-8/18422456_10154933198924475_7615455308585216370_o.j pg?oh=20ffc18818c6d31efaef3c19f36b336f&oe=59A22D59

[Grumph]

I presume marine applications usually means lots of constant state throttle and in my ignorance presumably throttle response can be lethargic with little penalty as there has to be lag getting the water to comply . Whether these systems are masked in this environment? I don't know.

No - marine applications do have some odd requirements but instant response is definitely required.

The old 2 stroke powerheads had some unusual ignition features to make them work. Timing was very much throttle position related. To the point that a slow trolling throttle might actually run very retarded - but give it a handful, and there's a heap of advance comes in.

[husaberg]

The last thing I'd want to do is to turn this forum into a Facebook-clone, but sometimes it would be nice to have a 'Like'-button. Like right now :niceone:.

star shaped button at the bottom of each post Frits is user reputation
Think of it as a like and dislike button.



And maybe thow in some budget to buy some nice trousers.

Neil would go for Lederhosen
http://img1.exportersindia.com/product_images/bc-full/dir_23/677303/lederhosen-bavarian-lederhosen-trachen-lederhosen-957955.jpg

[TZ350]

https://scontent.xx.fbcdn.net/v/t31.0-8/18422456_10154933198924475_7615455308585216370_o.j pg?oh=20ffc18818c6d31efaef3c19f36b336f&oe=59A22D59

Great project, I love it. ... :niceone:

[F5 Dave]

Was kinda wondering if you'd find a dyno to fit that.

[TZ350]

330988

Posted because someone asked to get a better look at my Honda NSR cylinder to GP100 crankcase adaptor plate.

330989 330987

All the original crankcase stud holes are plugged with alloy rod glued and screwed into place. Three of the new studs for the NSR cylinder are fitted into the GP100 crankcase, the fourth is in the adaptor plate.

I have no idea how big the crankcase volume is, but it is huge, must measure it some day. Long rod, RD400 115mm original is 100mm CC, crank wheels slimmed down and with the gear box spacer plate the flywheels are 12mm further apart than standard.

330986 330985

Comparison of blowdown area of ported NSR cylinder on the left and standard one on the right.

[ief]

Hi all,

am I right in thinking that an even tubmax would make for easy jetting or is that bs?

[ken seeber]

Cracked head stud boss in pic 4.