JUST FINISHED CONVERTING A POULAN 69 cc ENGINE AND AM SPINNING A 20X10 PROP AT 10600 RPM IS THIS TO HIGH.WHAT IS THE BEST RPM TO PROP FOR?IT SEEMS MOST ARE RUNNING THERE ENGINES 7 TO 8K.IS THIS THE BEST RANGE FOR ENGINE LIFE?
I DONT WONT TO BLOW UP THIS ENGINE BUT IT REALY STARTS TO PULL AT 9K PLUS.
WHAT DROP IN RPM IS NORMAL PER EACH ONE INCH INCREASE IN DIA?I AM ORDERING A 22X10 TO SEE HOW IT WILL TURN.
THANKS FOR YOUR INPUT

On my 70cc Brison I use a menz s 24x10 I usally prop for 6700-7000rpm on the ground. My g62 likes a 22x10 but I think it will be too light for your engine.

Randy

thanks for the info i think i will try a 24*10 also
where do you get menz props i am using a zinger and have read that some think they are junk
what do you think?

I just got my Ryobi 31cc converted and today I put about 30 to 45 minutes break-in on it. It was swinging a 18-10 Zinger prop at 6,300 RPM on a 32:1 gas-oil mix. It was running on the rich side and throttle down to a steady 3300 RPM. I monitored the head temp and didn't allow it to exceed 300 deg F. After 10-15 minute runs I let it cool down to the ambient outside air temp, about 75 deg. I'm a bit concerned that the exhaust oil residue is very black. I hope it isn't from engine metal. Anyone have any ideas?

After today's test runs, the engine was noticeably easier starting and better running. It has been recommended that the Ryobi have a break-in of 4 hours of which 2-3 hours can be inflight time!