I feel if it was just misaligned when he tightened the chain, that it would pull all the time. He says its only when he is on the gas, leading me to believe its the chain pulling on a loose bushing or bad bearing. If it does the exact same thing even when the front tires arent on the ground, dont waste time looking at the front end, it has to be in the swinger/carrier somewhere. Keep us posted on what you find/dont find lol