I've a Honda GCV135E unfortunately I got to close to a lamp post with a bolt sticking up it stopped the mower dead now there's a backfire when starting and it runs now with some vibration anyone know the timing belt set up I'll check the blade for straightness first though.Is the retaining bolt for the blade a left hand thread.

Peter, January 2014

Blade bolts usualy normal thread. Vibration may not just be from damage to blade. A severe shock can also bend the crankshaft, check it for true. Also check flywheel key for a partial shear caused by shock of the sudden stop. This could cause a back fire as it will alter timing. Hope this helps

Smudge, February 2014