I am aware of the Ryobi 31cc and 28cc two stroke engines. Does anyone know of any other size of Ryobi that is a two stroke? Is there any special differences in converting the 28cc model - have already done two of the 31cc models, both long shaft.

Sides7

The 31cc & 28cc Ryobi's are pretty much the same. You can use the 31cc cylinder and piston assembly on the 28s and vice versa. Most Ryobi differences come year wise rather than through displacemet. The earlier ones have a slightly smaller crankcase and there are also differences in the reed back plate shape. Early pistons will hit the later cranks but later pistons will fit the early style. And so forth......Bob

farley9n
That answers my question. The last Ryobi I got looks to have a smaller case than the other two 31cc I have converted. Didn't know for sure what I had. From other threads it didn't look like the 28cc version, but still it had that smaller looking case. Thanks for clearing up this puzzle for me.

Sides7

This is my Ryobi 31cc new engine, bought from harbor freight store, $49.99, throw away lots of parts of the trimmer, and the core looks pretty good even now the rear cover need be trimed and muffler still heaviness. Imagine the sound and power in the air........
I can't wait.