I converted a 28cc Ryobi a year ago and have been flying a 1/4 scale cub with it. As this left me with no string trimmer, I picked up another new one on sale. It never ran worth ____. Almost impossible to start, and when it did run, it would not rev up at all.

The problem turned out to be that the ignition timing was way off. When I compared the sick motor to the one I was flying, I could see that the timing was off (retarded) by at least 30 degrees in the sick engine. I filed off the cast in key and tightened the flywheel on the taper at the same position as the healthy motor. The motor starts fine now and revs up normally. I never determined if it was the cast key or the machined slot in the crankshaft that was off.

Just something else to watch out for!

Thanks to your knowledge gained from converting engines, you just fixed it?

Good job,

Jim

Nice catch Sprotflier. Your the man. I wonder if you put both engines at TDC... top dead center...then look and see if the slot in crank is posistioned the same with each engine. Thanks Capt,n

After my second Mac's crankpin chewed a hole in the backplate, I fixed one by driving the crank pin back into place with a drift and filling the hole in the back plate with JB Weld. Has held up for a few years.

Enjoy,

Jim