It is the engine, In neutral when I give it gas it shakes worse. It has power just shakes. Is it something to do with the balancing of the motot?Does the shaking increase with speed or RPM? Just trying to determine if it's engine or wheel related.
If speed related look for bent rims / loose spokes. Maybe a gob of mud or a rock stuck in the knobs. If it goes with RPM I'd say something in the counter balancer is broken or out of time.
With the oil cap off and running it's normal to feel what you describe, just venting of the piston reciprocating.