Originally Posted by crassius
you need some kind of solid front mount - the noise you're hearing is due to the motor leaning to the left so the chain can't run true
Absolutely correct. If the front mount isn't secured to the frame the engine is free to twist to the left which causes chain/sprocket misalignment.
Fix the front mount before you ride the bike again. You're setting yourself up for possible injury if that rear mount gives way and locks up the rear wheel. Not just a maybe, but a matter of time before it happens. Fix the mounts!