yeah i have the bolts very tight but when im riding i can see the motor moving a lil bit..i guess ill ditch the rubber
There is one simple test you should do at least every time you add fuel:
Grab the top bar with one hand and the top of the head with the other.
Now try as hard as you can to shove the engine back and forth.
No kidding here, give it all your arms can do.
If it moves AT ALL that is a fail.
A big common mistake is not getting the back motor mount to a nice 90 degree angle from the seat post, all of your engines pulling force is here and it has to have full contact, not just an edge of the mount.
All your lateral torque has to be handled by the front mount.
I don't dink with the stock front mounts, I use a muffler clamp that fits the downtube, a steel plate (via the SickBikes front mount kit or shop fabbed), pull the studs out and bolt the plate to the engine with good bolts.
The difference with a muffler clamp opposed to just a U-bolt and flat plate against the downtube is the all important grab to resist lateral twist.
A bonus with the SBP front mount kits is an assortment of spacers for those really wide bike cavities and you can put them on the nice fat U-bolt.
This won't help vibrations from a poorly balanced or timed engine but it will make it more bearable and your engine won't fall out ;-}