[2stroke] Ryger engine

Yes, close the inlet 5-10° earlier, you can try this.
It is a very easy to do test.
You could also try a smaller carburetor.
Maybe a 39mm Keihin will be 'easier'

Jan what did you consider "long inlet timing?"

On the 50 and 125 engines 135/75 was used.
Anything longer I do consider a 'long' timing

You had the advantage of being allowed large carburetors. With our rules the carb size is limited to 34 mm with a 440 cc twin so in order to get the maximum power I have used 150-90 but it is very hard to start

Jan, what do you consider to be the TRUE opening point for the Aprilia?

The angled valve edge actually starts to open the inlet port at 159 degrees. The Aprilia disc valve timing template (the one used to grind the discs from) is set at 142.5 degrees, but the valve is already revealing approx 100mm2 of port area at this point. It appears that the opening edge of the disc is about half way up the port at 142.5 degrees.

One could think of lots of "soft opening" shapes for the disc. Did you try angle other angles on the opening edge of the disc?

Thanks, Paul

Frits I see that the Ryger Facebook page is quite blank now. There were briefly a couple of photos pasted of the Ryger piston that are gone. Luckily I did save them! The piston appears to use an upper ring and a lower ring on a small diameter section that the rod attaches to with only an exhaust skirt and a fairly thin head. It must rely a lot on the transfer to keep it from overheating because there looks to be very little heat transfer area to the cylinder wall. Looking at the piston head and how the lower smaller diameter portion must fit into to a small cylinder I can see how the head doesn't take any of the thrust. It would appear that the effective area below the head is about 1/2 that of the actual displacement though the primary compression still appears be extremely high. That would effectively "force feed" the transfer through the transfer ports at a high velocity. The intake appears to be fed directly through the reed into the transfer ports using the momentum and the pipe signal to help it. Is my imagination correct? Or can I read a lot into your silence?

Howard, I'm very curious about those photos you saved. Could you post them here?

Howard, if you were referring to the picture (which I couldn't insert for some reason) which included a con rod, then I must say it was a dodgy mock-up made by some dodgy guys in Perth, WA. The intent was to stimulate some discussion and thoughts as to the configuration of the Ryger engine. However, it is an arrangement that is "sort of possible" to be configured within the envelope of the engine externals that we have seen posted: VM crankcase, 20 mm spacer plate and a standard outwardly appearing KZ style cylinder (albeit with the reed entry into the cylinder, rather than the crankcase), plus other features such as the 90 mm rod, 54.5 stroke and a full skirt piston when viewed through the exhaust port.

Howard speaks about photos, not 2D pictures, his description seams very right with the patent technical data. We like to see them.
Dan

The two photos were taken down for a reason so I suspect they are legit. One shows someone holding the piston by the narrow part with the head only showing and Ryger embossed on it. The other photo shows the side view with the rod connected and plastic caps over the ends of the pin. In order not to piss off whoever deleted them I will keep them to myself for now. I can't believe nobody else saw them!

Howard Gifford a écrit:

The two photos were taken down for a reason so I suspect they are legit. One shows someone holding the piston by the narrow part with the head only showing and Ryger embossed on it. The other photo shows the side view with the rod connected and plastic caps over the ends of the pin. In order not to piss off whoever deleted them I will keep them to myself for now. I can't believe nobody else saw them!

From your description I can guarantee that those photos did not show a genuine Ryger piston.
Now I'm doubly curious, so let's see them!

Then there is no reason to show them if they are not legit. Very curious that they disappeared so quick if they were a hoax.

I also downloaded a picture today of a skid of Ryger cylinders stacked like chord wood with Ryger clearly cast onto them. In the photo you can see into the Reed cage by blowing it up to maximum magnification.  The inlet port seems to  communicate directly to the transfers.

Howard, this is the dodgy piston I was referring to:

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No that isn't even close

I think it will end with a big disappointment.....
No power, no revs, no reliability

Hi. Where the Ryger Facebook page is going? Deleted? What's going on there? Best Regards

In the circumstances, it sounds like you might as well post them up Howard.

Best Regards

Ian

As I said im not going to repost them but if you look on Kiwibiker one of the photos is still there. It shows the end of the piston with someone holding what appears to be a smaller diameter section
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Howard Gifford a écrit:

As I said im not going to repost them but if you look on Kiwibiker one of the photos is still there. It shows the end of the piston with someone holding what appears to be a smaller diameter section
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If you won't, I will, Howard. There are two pictures on the Kiwibiker page you referred to.  Below you'll find both of them.
The piston with 'Ryger' written on top is genuine Ryger; the other picture is not.
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And while we're at it, here a couple of Ryger cylinders:
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And the first picture of the Ryger 125 Revo production run:
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The photo of the piston is one of the photos. The other photo I have shows the same piston with a side view showing the rod attached. I'm glad you confirmed it as genuine. The drawing you posted isn't what I was referring to but the exhaust skirt is the only similarity. Both photos were on Facebook but disappeared. Whoever deleted them I am sure didn't want them to become public

In the mean time I've had more thoughts on the Ryger and have come to the conclusion that the FOS might make a real nice base for a Ryger test cylinder. A modified version with the same exhausts but different transfers and a tight crank case pump. The Ryger uses the tight crank case pump AND open straight though ports. The transfer ports are double action both piston ported to this tight crank case (short piston), at TDC AND straight through at BDC. There is a reed in the transfers but it's also a diversion valve. Will shut off either straight in port or transfer port depending on the pressure it "sees". Sprung to shut the crank case transfers normaly, as the transfers open the high pressure port wins and out shoots a charge but not much volume, as pressure drops the reed will shut and the chamber will start its normal action with some help (augmentation) from the initial high pressure shot, now drawing straight from the carb. This system automaticly adjust for cylinder pressure, so blow down is no longer a problem. The 30mm carb "sees" draw at both top and bottom stroke, double time, with the piston porting setting up a sharp induction wave to help (this could be set to be most efficent at perhaps the time between 13500 to about 15500 when the chamber is out of phase?). As the engine increases in speed (chamber and exhaust outlet are the same size as normal) the pressure inside must increase so I would imagine the wave action would become more savage (energetic) and work much harder than normal, above normal speeds.
Dynamic compression would increase a lot at high RPM, being that the exhaust is the same size as normal, there by helping the HCCI process. Runs normal spark at low rpm. there I said it.

For me, the piston top is conical, like a cup ( female ): the size of the R R ( Ryger name) are différents, the smaller close to the center. The reason? to increase the combustion chamber volume and réduce the compression ratio, other: to center the piston under combustion load?

A mon avis, la calotte du piston est creuse, conique; les R de Ryger sont de taille différente, le plus petit près du centre. Pour quelle raison? augmenter le volume de la chambre de combustion et réduire le taux de compression( si volume de chambre imposé), autre: centrer le piston lors de la combustion ( réduction des forces latérales).
Dan

uniflow a écrit:

There is a reed in the transfers but it's also a diversion valve.

not confirmed and I still think there are none.

An interesting factor should also be the difference in displacement between the combustion side and "pump side" of the piston. From what little I could see on the forums, I estimate that the pump side has about 2/3 of the engine displacement. My guess is that plays a role in the amount of fresh mixture that ends into the exhaust duct.