ESE's works engine tuner

[katinas]

A couple of years back i had a (now moved) neighbour that was a financier for the ryger project.
During a street bbq he told me lots of details going on during development.
At that time he also told me that they where having trouble with the piston.
I had a private chat with a common friend of jan and me where we sometimes exchanged ideas about his zundapp with verry powerfull output. I also told him what i heared about ryger.
This information ended up at jan who shared it with the world as he likes to share his knowledge we are so thankfull for.

It kind of got me in a position where i didnt want to be. Harrie contacted me and so did my loaded neighbour.
And i felt bad for it fore a while. As a romantic enthousiast i always hoped they would succeed. First of all for the saviour of the two stroke and for the proudness of also beeing dutch. If thats worth annything.

I never signed disclosure.

Thanks, your words returned some memories from testing with rygerised NS/CR barrels and now very funny to found my own mistakes everywhere that really must do influence on engine performance. Maybe needed to write some words. ( Add pic, with another mistakes on piston that was not tested and plate that designed to do things without assistance from under piston pressure at BDC just direct flow from carb to trans).
Remember one video from short testing on straight, with really nice engine sound, but maybe this was not just separation plate with normal scavenging like showed in homologation papers.

Not in theme, but when my kids switch on to war mode, and then I tried show them peace flag, I always left guilted.

[katinas]

I remember in the late 1990's honda openly wanted to lower the cc's of the 500 class to 375 or something i could never figure out why
Do you have any ideas it was kind of playing into Aprilias hand dropping the open class size.

Looks like this was consideration between three cylinders 375 and two cylinders 500 for private teams, but 500 V2 wins. Interesting, on V2 prototype they even tested 17.5 inch front wheel to solve some problems with front and engine with firing on both cylinders at the same time with crank pins offset 100 degrees, like between the cylinders. But normal production racing version had firing between cylinders about 78 degrees with crank pins offset 22 on 100 degrees V2 engine.

[Sandokan]

Well you had the Microscope not that long back and now you want something else? That's just greedy.

Im not sure what you mean by this dave?

[jbiplane]

Implementing... Hope test soon

[Michael Moore]

below right is a bathtub head, looking rather like a bathtub, wouldn't you say?
Attachment 340972

FWIW, back in the day that Bultaco combustion chamber design was often called a "trench head" here in the USA.

cheers,
Michael

[F5 Dave]

Im not sure what you mean by this dave?

Just an attempt at humour, but if one has to explain it then I guess it was a bad attempt. I'll try harder next time.

[Sandokan]

Just an attempt at humour, but if one has to explain it then I guess it was a bad attempt. I'll try harder next time.

😂 well dave im glad. Realy thought i offended you.

[katinas]

Implementing... Hope test soon

Good to see your work and trying to save some pumping volume with smaller lower piston construction.

Worst thing with my engine was zero torque at mid rpm. In my case with upper 57mm and lower 38mm and 50.6mm stroke, pumping capacity lowered from 129cc to 71,7cc, and this reduced pumping volume, maybe do big influence on very low performance at mid rpm.

With stepped piston, tested two different cylinders, one from Honda NS 400 other from CR125, but both with normal scavening,
Whatever I try with different modifications on both cylinders, one thing was always the same - zero torque from, aproxx 3500 to 7000 rpm, . All additional variations helps boost power just in pipe working zone aprox from 8000 to 12000rpm.

Driving from 0 to 3500 rpm was acceptable and not changed from normal engine, can ride uphill easy, but just until 3500 rpm. Then, when I wanted to jump over ZERO torque zone rpm to 7000 level, I must operated with gas in the way that I never try all my life before. It took about 30 seconds in first gear (street ratio) when revs slowly rise up to 7000rpm, then all goes in normal way. It feels very similar to normal engine without one reed leap take off. Maybe much thicker reeds leaps would help.
When main central intake window was blocked on CR cylinder, power suddenly rise up at pipe working range. Big difference, remember was bests from all previous tests, but side lower windows between crankcase and transfers channels still left opened. This is where tests was ended, because when I put new ring for new test ,simply forget to adjust piston ring gap, and very soon piston was destroyed.
Another thing is very short 92 mm conrod (original 109 mm). This changed piston and flow dynamic. Piston acceleration higher through 90-TDC-270 ( pressure changed faster under the piston and compression too) and slower from 270-BDC-90 ( slower pressure build up under the piston, lower velocity through transfers, longer opened trans windows with the same cylinder in comparison with 109 mm std). Maybe not very accurate comparison, but with the same stroke its like opposite to four stroker intake . With short conrod on four stroke, intake flow dynamic is like on two stroke with long conrod.
With stepped piston there is no needed thrust on main piston skirt, so this let to do shorter main piston skirt all around where transfers windows are located and this appears possibilities switch on transfers windows in suction mode, when piston moves up and skirt opens transfers windows. This let mix flow from carb, directly to transfers if there is connecting channels between them.
On normal engine with special piston, this mix traveling way, can do work alone, without any pressure assistance, from the moment, when piston skirt side edges closes transfers windows on down stroke and until opens again when piston moves up. At this period, pressure under piston, works just like spring, as no any way to go out, as space is isolated. On this configuration, carburetor communicate with crankcase, only when piston side skirt open transfer windows. Surprisingly it works, power no worse than with normal scavening, even just with only Boyesen channels for intake, as main center intake window was blocked to arranged all flow directly to transfer channels. But this was not tried with stepped piston.
Interesting thing, that is not work, is compressor mode, when tried under piston squash at BDC with CR cylinder test. It take too much pumping looses and with bigger gap engine work better.
Best thing would be to minimize all pumping looses as much as possible and at the same time keeping flow through engine.

[jbiplane]

Best thing would be to minimize all pumping looses as much as possible and at the same time keeping flow through engine.

Hi Katinas, thanks for so detailed description of your experience. According CAD model I have "crancase" volume changing from 499 to 222сс.
The base engine is snowmobile 2-cylinder inline RMZ550 76x61mm.
Will see how it will work. For me important to have good power on high rpm, cause this engine will drive propeller (brake load depend of rpm in cube).

The next iteration should be something like this

[Tim Ey]

Hi jibplane,

you re-invented the "Kurbelschlaufenmotor" from Ficht. But on the Ficht engine, the Conrod is cylindric with a seal to divide crankcase and pre compression chamber. Also the piston can be produced on a lathe since it is screwed to the rod through the piston crown with a sunk in screw.
Benefit: Pumping likewise regular twostroke engine, very good sealing from crank to cylinder, lower conrod bearing can be pressure fed, no upper conrod bearing, no mass forces 1+2 order, no lateral forces on the piston, 2stroke oil only required to lube the piston, no piston pin.
Downsides: The "Kurbelschlaufe" that sits on the big end is quite a hassle and everything needs to be exactly parallel and perpenticular.

If you get this done as a 4cylinder boxer engine with your injection system, you may either build a 4-2-1 pipe or a 4-2 pipe.

[Michael Moore]

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

That looks like a Scotch Yoke at the crank, I thought it would need something like that. Those usually seem to be limited to slower-speeds, I've seen them used in large sheet metal nibblers/trimmers. But aero engines often seem to run at fairly low speeds, I presume to reduce the need for a propellor speed reduction drive.

cheers,
Michael

[peewee]

what was the theory of how ryger would have so much power ?

jbiplane: if i understand it sounds like good crankcase pumping is important at middle rpm but at high rpm when pipe is working then the crankcase is not so important ?

[Frits Overmars]

Hi jibplane, you re-invented the "Kurbelschlaufenmotor" from Ficht.

https://de.wikipedia.org/wiki/Kurbelschlaufenmotor
That looks like a Scotch Yoke at the crank, I thought it would need something like that. Those usually seem to be limited to slower-speeds.

Michael, you're quite right about the Kurbelschlaufenmotor using a Scotch Yoke and about it's sliding movement rendering it unfit for high rpm values.
But the video posted by Jbiplane did not show a Scotch Yoke crank, but an epicycloid crank, with no sliding movement involved, and much better suited for high revs.


Neil Hintz, aka Flettner (who else?) already showed his version some time ago.

[husaberg]

Michael, you're quite right about the Kurbelschlaufenmotor using a Scotch Yoke and about it's sliding movement rendering it unfit for high rpm values.
But the video posted by Jbiplane did not show a Scotch Yoke crank, but an epicycloid crank, with no sliding movement involved, and much better suited for high revs.


Neil Hintz, aka Flettner (who else?) already showed his version some time ago.

[Frits Overmars]

Yes Husa, we should forget about reciprocating rods and pistons altogether.
The Wankel was a brilliant idea, if only it wouldn't have such a lousy combustion chamber shape and ditto surface area to volume ratio.
What's next? Electromotors, that's for sure. But how are we going to feed them and achieve some decent mileage?
My hopes are pinned on fuel cells; not the original hydrogen-processing kind, but the kind that will accept liquid hydrocarbons like petrol or methanol.