Originally posted by kevin mcgrath
Well I sold my large two strokes a while back and memory fades,so the best way to answer your question is to say a decent Ryobi will turn an 18x6 or 16x8 Zinger at 7000 with no problem,but will outweigh a 1.2 2stroke glow by a large margin.Trying to replace a stout 1.2 2 or 4 stroke glow with a Ryobi,even with a CH ignition is a marginal deal,and probably not a good idea if performance,such as the dreaded hover and unlimited vertical is your idea of fun.This would be the work of something like an RCS 1.4 IMO.
Gas looks better and better the farther up the size scale you go,and 1.20 sized planes are about minimum for conversion.
My C$.04 worth.... 
I did a lot of work on Ryobi engines, and am/was stumped by the many changes they made to the cylinder setup, just to reduce the maximum RPM that the engine would be able to do in a weed whacker.
On the elder types, I experimented with enlarged membranes and rotary inlets. I finally got about 7000 rpm with a Menz_S 18x10. The work, and drawings of the modifivations are documented on my personal web at
www.reivers.myweb.nl
The plate valve now flies somewhere in Texas. I traded it with a Ryobi engine.
I hope the information is useful.