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I just repaired my 18.5 HP OHV engine (replaced the connecting rod) and now when I try to start it, it will not start. It backfires and sherd the key on the flywheel (twice). I verified that I aligned the two dots (Crank shaft and cam shaft). I also adjusted the valves. Not sure what I am missing here, can anyone help me?

Scott

Start with removing any oil or grease residue from the crankshaft taper as well as the taper on the flywheel, and then torque to proper limit Backfire shouldn't be shearing the flywheel key, but if it is shearing on start attempt could result in the problems that you are having.

ILENGINE,

That will address the issue of the sheering key, what about the issue of it backfiring. I checked the alignment marks and the valve adjustments. It looks like a timing issues, but I am not sure what else to check.

Here is all the work I did:

replaced the connecting rod, piston, rings.
honed the cylinder
reassembled

it tries to fire but only backfires and will not start.

Scott

I was thinking that the key was shearing which could be causing the backfire. if the timing marks on the crank and camshaft are correct, and the valves are adjusted correctly you shouldn't have a backfire problem. Possible that one of the valves isn't sealing properly.

ILENGINE said:

I was thinking that the key was shearing which could be causing the backfire. if the timing marks on the crank and camshaft are correct, and the valves are adjusted correctly you shouldn't have a backfire problem. Possible that one of the valves isn't sealing properly.

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I suspect torquing flywheel by gosh and by golly partially shearing key just trying to start.

Walt Conner