Internal geared hubs, Whats good,What ain't

ive been using the alfine 8-speed and have had nothing but problems.
here are my specs:
68 cc skyhawk, piratecycles high comp. head
sbp h/d shift kit
30t sprocket off of the kit
24t sprocketto the rear wheel
23t sprocket on hub
the motor pulls strong and has plenty of torque starting up
at high speeds it skips and then slams into gear. i have broken the nubs off of the hub sprocket and today the axle snapped while trying to start it
it may be because of the 1:1 ratio of the pedal crank to the rear sprocket, which multiplies the torqu particularly when its pedaled but the 44t wont fit under the motor on my bike.
also, whe souldnt it shift properly when being driven by the motor? torque is torque and if the motor has only enough to move the bike from a standstill, then it shouldn't blow the hub!?
does anyone have any suggestions?

Most internal hubs require a 2:1 or higher ratio, or else the transmitted torque might be too excessive.

But, I think your problem is that you don't have the hub's shifting mechanism adjusted properly.