17hp Kohler backfiring through the carb. Water was in the gas but now O.K.

Dear wassup

I have a John Deere lawntractor with a 17 hp motor.
Backfiring through the carb sounds like a blown exhaust gasket...

I tried to single out the causes of carb backfire which I know could be water in the gas, timing, or hung up intake valve. I never thought the timing could be off due to the mower being belt drive but Sears was called out and the flywheel key was bent thereby throwing off the timing. If an obstruction is hit on a push mower it can bend the keyway. On a belt drive mower usually the belt will absorb the shock. I think, since there was water in the gas, that backfiring caused the keyway to shear and once sheared the timing was thereby off and it backfired even more. Just trying to help out the neighbor.

The flywheel key will shear usually, I don't think I've saw one "bent". There are however, offset flywheel keys on some units.