The GMS .76 engine is a ringed engine with a steel sleeve. You can buy replacement sleeves from TH for $17.00

At that price--I could try a few mods to it.

Has anyone ever done any mods to this engine?

I wonder how much you could get out of it if you checked and increased the intake and exhaust duration? I wonder what polishing it and matching the ports would do?

I saw a website that stuffs the case by wrapping a very thin steel sleave around the crank counterweight. Then they fill the area around the counterweight with lightweight material--to keep from throwing the balance off. They claim it works REALLY WELL!!

If ya think about it--there's probably about 3 or 4 cc's of volume around the counterweight area where it's machined up to the rod pin. If you could fill up that space and decrease the swept volume in the case---think of the acceleration into the transfer ports!!![X(] A couple cc's of volume in such a small space would probably make a huge increase in transfer velocities.

I'm really wanting to buy one with an extra sleeve for it. Maybe a ring too. Get out the dremel and the degree wheel--and go to town!!

What say you? Anyone ever tried it. Anyone willing to try it with me?