Re: 2 tires down, I must be doing something fundamentally wrong here...
Whenever I assemble a bike, I always lift the rear pull the clutch and pedal the bike a bit, watch and listen to the chain. I also do this spinning the rear wheel backwards. If all looks okay, and I hear no popping. Then before I ever fire the motor I pedal the bike around a bit. If I have a problem with the chain, sprockets or tensioner. This will usually allow me to catch the problem before I go buzzing down the street at 30mph.