Briggs engine won't fire after new piston rings on Craftsman mower---15.5HP

theticket said:
I got a compression tester and it read 125. I have not adjusted valves yet. I read on B&S website that they don't publish compression PSI, that they prefer a leak down test. Does this 125psi sound correct? The flywheel is turning and I wouldn't think that it would turn if the key snapped off or fell out, would it?
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125 psi is high, so check the valve clearances to start with. The engine will crank with a sheared flywheel key but will not fire at the correct time.
 
Possibly didn't put cam in correctly or the rings but thinking the valves is where u should start first before another tear down.
 
Check that your muffler didn't get plugged by some critter during your rebuild.
If it can't exhaust, it won't run.
Ever pull the potato up the exhaust pipe trick?
 
ILENGINE said:
125 psi is high, so check the valve clearances to start with. The engine will crank with a sheared flywheel key but will not fire at the correct time.
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I thought 125PSI was high also after reading other posts. I will check clearance on valves and check muffler for blockage before tearing back down. I will repost on results.
Thanks a bunch to all.
 
Sure enough, the key sheared off. I will get another one. Any advice on how to prevent this from happening again. Is there a correct way to insert the key to make sure it won't shear off again??
thanks for all the help
 
A taper needs to be clean & dry to lock in.
It also needs to be a close fit.
If a little lip has formed on the edge of the keyway on either the crank or the flywheel it will need to be removed or the taper will not lock no matter how tight you do up the nut.
 
OK, new key installed and flywheel torqued properly and everything is working like it should so far. Thanks to all!! I learned a lot....
 
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