good input...yes it could be an out of balance spinner or it could also be a bend crankshaft? If the engine was dropped at some point this can happen pretty easily. I dropped a brand new prototype 160DZ a couple years ago and bent the crank. We had to wait about 60 days to get a new crank for it as there were not any around! It had to be made in Japan. The 160 crank was beefy compared to the 140 version and it was not recommended to use the 140DZ crank...on the 160DZ

It would fit but was not strong enough and could give you problems.

Troy Newman
Team YS