IS THE "WEED EATER"BRAND FEATHER LITE 18CC A GOOD ENGINE TO CONVERT?
AND ALSO THE 25CC SAME BRAND ON A STRING TRIMMER.

RCM243

The 25 makes a pretty good engine but forget about the 18. Its not worthwhile.

Can you explain more why the 18cc ins not worth the effort? I do not need anything particularly powerful. I have a Sig AstroHog covered in Koverall that I have avoided flying with the OS61 glow in it because of the mess. A really small gasser would help in that respect. Is there anything lighter than the 18cc that you would recommend?

The little featherlite will only turn a 14-8 at around 7000

it might fly a "Hog"?

You would need to shorten the nose a couple inches for balance.

how are the 18cc featherlites after some porting and an increase in compression. if they are lighter than the 25cc then, i think it would be worth the effort. that is if you are a tinkerer like me

You need to at least change the carb to a 5/16" venturi version with both high speed and low speed needles.

ive heard of guys who can make the 25cc turn a 16-8 (i think) around 9000 rpm. doing the same mods to the 18cc should produce very good results with a 15-8ish prop. that should fly a 1/4 scaler around pretty good eh?