On the question of the cost of conversion of
a Ryobi 31 cc. For my part, I have done this conversion and I have a great
engine for less than $150.00 (less than half than comparable "model
airplane" gas engines). With that said, I just read a review of the Zenoah
G26 in an issue of Fly RC mag. Guess what? My weed cutter Ryobi
conversion turns a 16x10 prop at a higher RPM (8,100 vs. 7,260) and idles
lower (1,400 vs. 1,860) than the G26. And my tests are at 5,500 ft altitude
with 15% thinner altitude, which knocks the crap out of engine horsepower.

As for weight my Ryobi is almost 1/2 pound lighter (51.1 vs. 58.3 oz.). I
should add that I added a homebuilt electronic ignition and dumped the stock
one pound flywheel/coil assembly.

Granted my $150 total cost doesn't include some of my labor and my friends
machining (I owe him a lunch). I should add that I pulled the Ryobi out of a
new, reconditioned weed cutter from Harbor Freight. Cost $49.95.
Also my 31cc is 22% larger displacement that
the G26 @ 25.4cc which slants the comparrison in the direction of the Ryobi.

Therefore my observation is that the engine conversions are at least
comparable to other gas engines in their displacement class and cost less.
What's wrong with this logic?