do any of you guys know the measurment of a 31cc piston? i just tore down two engines and have two different size pistons!
both were suposed to be 31cc ryobi engines i dont get it.HELP!
FJ54

In some cases you get a 28CC Ryobi which the piston is smaller than the 31CC
I look at the crank case it is totally different than the 31CC case I'll take some pictures and post later as soon as my daughter brings my camera back.

aeronut: Your da Man!!!! Capt,n said that!

thanks you are correct its a 28cc no pics necessary. but it all worked out for the best
fj5

Well anyway here are some pic's as promised it may serve as reference for some one out there!!!! The one on the lefty is the 28CC and the one to the right is a 31CC

aero nut
thanks for the info hopefully someone else can use it to avoid my problems
however neither of those looks like my 28cc but thanks for responding
fj5

this engine is 20 years old its got a rough cast lower unit and the top three fin r small and has a square block behind the plug
its a long shaft and also is stripped \damaged crank shaft good for parts
i gotta stop saving all this stuff without checking it out first.
fj5