I started flying my Thunder Tiger Giles 202 1.40 size plane a few weeks ago and this has gotton me back into tweaking my Ryobi combination.

I have a long shaft old style bottom end that is basically stock, I swapped in a double ring piston the other day and it was suprising how much more compression it has. My starter would barely turn it over. I am running a bigger carb, a thin base gasket (.020), and a pits style muffler from wacker engines I think. The cylinder is n older single port per side with the decompression slots, no mods to the cylinder.

It will spin a 18x6 Zinger wood prop at 7500 RPM and I just bought a Xoar Sword 18x 8 which it will turn to 7000 RPM,
I have yet to fly it with the Xoar prop but am looking foreward to it.

Also I just found on ebay a brand new short block and a new cylinder, it is one of the old cylinders without the decompression slots. I am anxious to get these to give them a try. I am hoping the new cylinder will boost the compression even more and hopefully get some more RPM out of the 18x8 Xoar prop. I may even do a little grinding in the exhaust port to increase the exhaust timing.
where do you usually have to grind it out , on the top or bottom of the port?

I also have one more carb to try it is a big one, has a 32 stamped in the venturi, we'll see if it helps or hurts!

chris