I just acquired a Deere JX75 self-propelled lawnmower w/ 6hp kawi engine. When I start it, it vibrates like a jumping bean. It will literally vibrate sideways a foot within 10 seconds.

When I engage the blade it runs smooth and I can even engage all five speeds with it running smooth. Mow the lawn, etc,etc.

The motor is bolted securely and I would think it would vibrate even worse with the blade engaged if the crankshaft was bent.

Can anyone help with a diagnosis?

Thanks!

Hi,
Something I found out years ago is that it is almost impossible to straighten a Kawasaki crank. Sounds like that is what you are looking at, the crank will bow instead of straightening.
Peace,
Clarke