I can not get my new motor to fire for the life of me. It will turn over for a few seconds then a huge sonic boom comes out the tail pipes then nothing. All of the plug wires are correct and there is spark. Plugs gapped at .045 just like they are supposed to be. When I set the motor at TDC I watched when the intake valve opened then closed. As both valves were closed I lined up the timing mark with the pointer. Shouldn't that be #1 TDC? What am I doing wrong? Everyone around here says it is 180* out. So that would be one full revolution of the motor after my inital setting. This whole thing is going to end up on the camp fire.