Small Engines (Lawn Mowers, etc.): back lash, honda gx390, stump grinder

Question
i have a stump grinder powered with a honda gx390, it has a back lash ever time i pull the core, does this engine have a pressure release value to start it.

Answer
Sal

Sounds like the timing is out,check the key way on the engine shaft. To see if they are lined up together,When the engine suddenly stops or gets a quick pulse especially  when using a stump grinder,the momentum will cause a sudden jerk,Like hitting a stump or a pipe when using a regular mower the sudden stop causing the shear pin to break rather then your engine crank,pistons,cam and valves.