ESE's works engine tuner

[2005bully]

Perhaps the primary compression chamber is quite small, much smaller in volume than the engine capacity, but still acting as a pump at low speeds to get enough gas in to run the thing until it gets on the pipe. Then the pipe takes over and the volume of the compression chamber becomes unimportant, as long as it can flow well enough to allow good filling.

Lodgernz.... One side effect of a very high primary compression ratio is that the transfer mixture enters the cylinder at higher velocity. This increases the incoming mixtures chance of intermixing with residual ex gasses. But it certainly would create a low pressure in the ports immediately after the mixture was uploaded to the cylinder. Separating the engines lubrication oil from the fuel and still using crankcase methods of pumping is not a simple exercise. A diaphragm between the crankcase and a secondary transfer chamber might be one of the simplest possibilities. If such a diaphragm had limited displacement it might get the whole process started, while limiting its negative effects at higher rpm's. But adding movable parts goes against keeping it simple. Stumped....

[MotleyCrue]

You will only get the power if you get the scavenging and the combustion right, and then the fuel economy and the emissions will come automatically.

Just thinking out loud here.

Since torque is no greater than for a regular top level 125, then combustion wouldn't really be better in the sense of creating more torque, unless ........... combustion is a little better and scavenging is a little worse so net torque is pretty much unchanged.


The engine can only at best retain in the cylinder what its able to get to the cylinder in the first place, so the overall flow through the 30 mm carb has to be more, quite a bit more, at 17000 rpm than at 13500 rpm. The only thing creating a big suction is the exhaust so the exhaust must be "seeing" the carb better or for more time (or both), than in a regular engine.

In order to have good emissions and economy, the scavenging must be such that any and all air/fuel getting into the exhaust port gets shoved back into the cylinder, easy enough when the engine is on the pipe but not obvious how this would be done at low engine speeds, part throttle, idling. Maybe figuring that part out is the real key to this riddle and the rest is gravy. I dont remember any poster's suggestion addressing this aspect but maybe I haven't read far enough back.

[jonny quest]

Did I miss where it was posted that the torque of the Ryger is that of a top level 125, and no greater?

[jonny quest]

If "primary compression" isn't really a pump anymore, the velocity wouldn't be very high anymore.

And if it's not a pump anymore. .. it really shouldn't be called primary compression ratio anymore, should it Frits?

I am just egging you on now Frits 😉

[MotleyCrue]

Did I miss where it was posted that the torque of the Ryger is that of a top level 125, and no greater?

I'm pretty sure Frits said is was slightly less than the Aprilia and that the Aprilia still holds the "title". Might have been posted on a different forum though.

[lodgernz]

Lodgernz.... One side effect of a very high primary compression ratio is that the transfer mixture enters the cylinder at higher velocity. This increases the incoming mixtures chance of intermixing with residual ex gasses. But it certainly would create a low pressure in the ports immediately after the mixture was uploaded to the cylinder. Separating the engines lubrication oil from the fuel and still using crankcase methods of pumping is not a simple exercise. A diaphragm between the crankcase and a secondary transfer chamber might be one of the simplest possibilities. If such a diaphragm had limited displacement it might get the whole process started, while limiting its negative effects at higher rpm's. But adding movable parts goes against keeping it simple. Stumped....

You misunderstood me, or I didn't make myself clear. I'm not talking about a high primary CR, I'm saying that maybe the primary compression chamber only sucks in a small amount of gas.
For example, if the engine capacity (swept volume) is 125cc, maybe the primary compression chamber only sucks in 30cc, then pokes that up through the transfers at a normal sort of rate, depending on the physical size of the chamber, let's say 50cc. Once the motor is on the pipe, the volume of the chamber is less important as the pipe will be pulling the mix through it, especially if it has a shitload of transfers...

Forget about diaphragms. Crankcase isolation will be via the piston, whatever that may look like.

[2005bully]

You misunderstood me, or I didn't make myself clear. I'm not talking about a high primary CR, I'm saying that maybe the primary compression chamber only sucks in a small amount of gas.
For example, if the engine capacity (swept volume) is 125cc, maybe the primary compression chamber only sucks in 30cc, then pokes that up through the transfers at a normal sort of rate, depending on the physical size of the chamber, let's say 50cc. Once the motor is on the pipe, the volume of the chamber is less important as the pipe will be pulling the mix through it, especially if it has a shitload of transfers...

Forget about diaphragms. Crankcase isolation will be via the piston, whatever that may look like.

I'm confused ...... If the primary compression chambers pressure is directly influenced by piston movement what limits the volume sucked in to the example of 30cc. Then where does the extra 20cc come from when it pokes up through the transfers? On the other hand if the primary compression chamber is not directly influenced by the pistons movement then what causes this chamber to produce any draw? Excuse my miss understanding.... What am I missing here.

[seattle smitty]

Am I wrong in thinking that Frits disclosed what might be THE essential hint about 15 pages ago, and that the discussion has remained somewhat peripheral to that hint? Top of page 1295 . . . detonation . . . ???????

[husaberg]

You misunderstood me, or I didn't make myself clear. I'm not talking about a high primary CR, I'm saying that maybe the primary compression chamber only sucks in a small amount of gas.
For example, if the engine capacity (swept volume) is 125cc, maybe the primary compression chamber only sucks in 30cc, then pokes that up through the transfers at a normal sort of rate, depending on the physical size of the chamber, let's say 50cc. Once the motor is on the pipe, the volume of the chamber is less important as the pipe will be pulling the mix through it, especially if it has a shitload of transfers...

Forget about diaphragms. Crankcase isolation will be via the piston, whatever that may look like.

Ill bite, How do you separate the crankcase with just a piston. Whist still maintaining a pumping chamber?

[lodgernz]

Yes, it was Honda's ARC (Activated Radical Combustion). The Honda EXP2 had an exhaust power valve that could severely restrict blowdown, so a lot of hot residual exhaust gas remained in the cylinder where it mixed with the next charge of fresh mixture, heating this mixture so it would self-ignite at the end of the compression phase. In Honda's case this only came into play at part-throttle. The Ryger is cleverer: it does not need an exhaust power valve at all and it works at WOT too.
Attachment 315837Attachment 315836

Certainly looks like a hint Smitty

[lodgernz]

I'm confused ...... If the primary compression chambers pressure is directly influenced by piston movement what limits the volume sucked in to the example of 30cc. Then where does the extra 20cc come from when it pokes up through the transfers? On the other hand if the primary compression chamber is not directly influenced by the pistons movement then what causes this chamber to produce any draw? Excuse my miss understanding.... What am I missing here.

Ill bite, How do you separate the crankcase with just a piston. Whist still maintaining a pumping chamber?

I was thinking maybe a stepped piston?

[jonny quest]

Top hat. Brim down.

And could this brim also close the transfers to prevent flow out the exhaust? Could this piston have a mission for emissions?

[peewee]

In order to have good emissions and economy, the scavenging must be such that any and all air/fuel getting into the exhaust port gets shoved back into the cylinder,

or maybe no unburnt a/f ever makes it to the pipe (or escapes the cylinder, which ever way you want to look at it), which might be what frits was suggesting on pg1295

[husaberg]

I was thinking maybe a stepped piston?

Already ruled out as supercharged.
FIM says 2 diameter pistons are illegal from memory

[Flettner]

Top hat. Brim down.

And could this brim also close the transfers to prevent flow out the exhaust? Could this piston have a mission for emissions?

No, other way up. So the pumping volume is the difference between the large size and the small size. So it will be less than 125cc.