I have never flown Gas only glow, but I was given two stihl string trimers. The label on the cover has FS51av electronic. I don't know any thing about the conversions,but I would like to try it. Would one of these engines make a worth while conversion? Any info on displacement of these engines would be appreciated.

On the trimmer you mentioned, you may need to clarify and obtain some info from local Stihl dealer. Get us some displacement size and pics if possible. One good point is they were free and you have two of them for parts and experimenting.

Get some more info and there is a lot of assistance available .
Had my curiousity up and could not find where Stihl shows trimmers on their site but it was just a quick look.

hi
just converted a stihl51av electronic to to spin clockwise .. Had to make a adaptor to house the new da ignition ( lighter ) and remove unwanted housings .. After getting it going it spins a 18/6 prop 5000 rpm ( a little bit under compressed ) but not too bad..Estimate it to be approx 27 cc is all the info I can find still to confirmed.. Ignition cost $220.00 money well spenteasy to convert...

$220 ? Couldn't you buy a whole engine for that much?
I think G-26 cost around that much. My buddy got one in a Sig rascal 110, and it flys great. It will even hold it in a hover (kind of).

antslake, can you provide ANY helpfull information or just be arbitrary to others?

sprocket, Good place to start on the rpms. see if you can get a slightly larger carb and make sure your muffler is free flowing, no baffels, you might gat another 1k rpm out'a it. Piper

thanks for the support pipercub
I tried it with and without the baffle using an os 160 pipe not too bad but max rpm was without the baffle , even tried without the endcap 5000 was max remember the engine is worn and not much compression . Also the carb is a Wilbro off an echo whipper snipper a little bit bigger with a velocity stack....keep in mind the currency rate $220.00 aust...about $130 us ... Just about to do another conversion on a ryobi approx 30cc for a mate seems to be a but easier with correct rotation for a start , rear carb and exhaust and a shorter nose on the eng. heaps of compression..let you know how it goes...

I have several ryobi's flying and its about the best engine out there for low cost and ease of conversion and best of all, once you cowl it you never need to worry about getting to it again. I will run the same year after year.

BTW: on my ryob's im getting about 7500rpm on an APC 18x8 wide blade using the conversion parts and carb from www.wackerengines.com . If you can turn your own flywheel down about $50 will get all the parts INCLUDING the large bore carb from him. Spend a little extra and get his muffler too. Hands down the best one out there and not because its the cheapest. The pipes are removable so you can make two holes in a cowl to put them through instead of a huge gash to slide the cowl around them