I have a john deere L110 tractor mower with a kohler 17.5cc engine,the engine turns over but will not start just back fires through the carburator.fitted new carb new spark plug clean petrol but still keeps back fireing throgh the carb (the machine has only done 120 hours ). It feels like the timing is out but how this has happened I don't know. Please inform me how to check this out and how to retime the engine.

Hi,
Flywheel key is sheared; a fairly common occurrence on the Kohler Command single caused by not idling the engine doen before shutdown.
Peace,
Clarke