I have been busy modifying Homelite 25 cc engines over the last month or so, gathering information from various web pages. Is there any information out there regarding Ryobi port mods?

Regards,
Dogg

I did a Ryobi 31cc conversion, that I used in an airboat. The first thing I would do is to get a Frank Bowman pistonring. The stock ring has a big gap where it is pinned, the Bowman ring raises the compression a lot. Since I used it in an airboat, I built the engine for torque, and not rpm like you need. I modified the reed intake, changed to a carb with 11mm venturi, raised exhaust timing to approx 162 if I remeber correctly , widened the exhaust, ditched the base gasket and used a sealer instead, modified the transfers and made a moussecan pipe. It was a strong runner when finished, I think I managed to get 89oorpm with an MAS 18x8. I did try the WT644 carb (12.7 venturi) and it worked ok, just a little sluggish on the low end, might suit your application though. I know that some of the Ryobi engines have a rev limiter, you better check that before you do a lot of work. Check out Rcuniverse and engine conversion forum, a lot of guys use Ryobi on their planes. I´m sure you will find Bowmans e-mail there too.

www.rcuniverse.com/forum/forumid_92/tt.htm