I have a Murray riding mower model 425600X8 with a Briggs & Stratton engine Model 31D777. When I try to get the engine to start, the flywheel turns as if to make a complete round. But when it gets to a certain point it will not complete the turn.
It seems as if there is a compression build up that stops the spin. The battery is fully charged, so there is no lack of power.
When I take the spark plug out the flywheel spins freely. Can you help me? Ben.

Ben Thorne, November 2007

started my riding lawnmower and all it does is smoke real bad and looks like its spitting oil...what can I do to fix it or what could the problem be?

mike, August 2012

I just had this problem and it was solved by resetting the valve clearances to .005 exhaust and .003 intake.

Craig Severson, September 2009

the problem you have is internal engine problems. briggs and stratton had some problems with heat treating of the camshaft lobes. after a period of time of running the lobes become swiped causing the valves to not open to a proper clearance, thus causing compression buildup causing the flywheel to turn one revolution and then stop abruptly.

denny edwards litchfield outdoor power, November 2007

Sounds like the timing of the engine is wrong ....have you hit anything lately>?
Sounds like the shear pn has been disturbed
Will need to remove flywheel and check the shear pin for correct position .........Proably find your problem here

bg, November 2007