exactly. now, if our motors had, say, four mounting points in the frame spaced out equally, a rubber mounted situation would probably work perfect. it would allow the motor to vibrate, but it would vibrate equally, or uniformly inside of a cradle. if balanced correctly, one vibe would cancel out another, and they would all share an equal load.
our main problem is we have two unbalanced, uneven mounting areas, attached to basically whatever we can find to bolt it to.
it's like a front wheel drive car with a broken torque strut (usually a dog bone lookin' motor mount if you haven't seen one.) as the name implies, when the car accelerates, the motor wants to twist. the torque strut keeps it from doing so. with a broken one, it will twist, and mike breaks an axle (i had a 75 civic hatchback with a non-cvcc 1600, dual mikunis, etc. 1/4 miled in 12's. had to build all solid motor mounts
)
now, applying this to our little two stroker, the torque is provided by the chain, especially at start up, where it wants to (and does) jerk the whole motor to one side, the engine chain side. there's no lateral mount, so we have to rely on the two in-line mounts to keep that motor from twisting.
with a rubber mounted set up, it will twist, and shear off the motor mount studs, or twist the rear wheel off it's axis if not tightened properly, or the motor flops completely out of the frame (all problems encountered on this forum.)
and honestly, if the motor was better balanced and we were able to mount it properly and securely, a cushioned motor mount would probably be freakin awesome.