Re: when replacing motor is it better to buy the motor or the whole kit?
If you replace the motor, you will have plenty of spare pieces already. The only way I would replace the motor is if I were carrying a spare on a long tour or something. Most of the pieces of the motor can be purchased for repair purposes. The non-motor pieces in the kit I would not bother having spares for their own sake. If you want a spare sprocket, get one a different size. If you want a spare chain, buy an upgrade. If you want a spare tank, make one from scratch. Cables you can scavenge. Most things you can fabricate or make do from locally available stuff.