Found what I think is a Poulan 31cc weed whacker with rear carb. Has anyone converted one of these and is it worth the time and effort. What plane and mount will work well with a converted engine with rear carb? I'm new to conversions and would like to start with an engine relatively easy to convert. Would this be it or should I keep looking. Thanks.

its probably a ryobi 31cc,the size and rear carb say ryobi.is the carb mounted in a plastic back plate? its a ryobi. check out wacker engines .com for parts such as prop hub mount muffler etc.its a fair engine to convert power wise.
recomended is 1000 sqr inches of wing no more than 14 lbs.im still working on mine ,building the plane.
good luck

Maybe is a Ryobi. It has the carb mounted on a plastic back and has a reed valve on the intake. It has a single ring on the piston. The exhaust is held on with a spring on either side and has no mounting holes. Not sure what to do about that. Turns out it looks like the engine got flooded during Katrina. Not sure if it is any good. It looks fairly old anyway, but shouldn't be too hard to convert.

sorry, now I dont know if it is a ryobi . never saw one with a spring on the exhaust ,the carb sounds right.
can you post pictures?that would be the easyest way to i.d. it.hopefully it will be something popular so you can get parts without re-inventing the wheel. maybe someone else can I.d it from your description,what make trimmer was it?

Took another closer look at a NEW Poulan 31cc, the one I have is nearly identical. The new one also has a rear carb. The muffler on the new one is secured with two screws though. The one I have must be an older model. I'm pretty sure though it is a Poulan. I'll have to check the numbers. Any ideas on how to mount a muffler? Are there stap ons for converted engines?

yep ,you got me, it is probably a polan, altho most that I can look up on line have a side mounted carb and rear mounted muffler retained by a spring.I looked at outdoor distributors .com for parts break down for polan string trimers
and there it was .sorry for the mistake. I'm not real sure about polan trimers pete at wacker engines .com can make parts for you or maybe ken lambert can help you . conversions arent hard ,its just some are heavyer than others
sometimes too heavy to use as an aircraft engine.some others dont make enough power to make it worth it. I cant find anything on this site about that engine wich I find really weird. any way good luck maybe someone else can help out I hope

Did a little research, it is a Craftsman 32cc Trimmer motor made by Poulan. Has a relatively long shaft in front. Is it okay to clip these and then re-tap? How about carb, should I try to modify or is there one I can simply swap with? I've got the case shaved down and weighed all the parts. Without muffler, all parts are just over 4 lbs including unmodified flywheel and magneto. I will shave the flywheel too if I can get the engine to run 7500 rpm or so with a 16/8 prop. That may be asking too much. We'll see.

Should get more than 7500 RPM. I am using a 16 x8 prop on two 25cc engines and get 8100 and 8200 RPM. 32 cc is a 25% larger engine.

Bill

bills: I wonder if the MB290 blower is really 29cc? A person would have to measure bore and stroke to find out. I wonder why why the model is MB290???? Thanks Capt,n[:-]

No such luck. Bore is 34mm. Box clearly states 25cc.

Bill

I know it says 25cc on box. I have run into wong data on box cc being wrong before. Tanks Capt,n