I recently got my LA out and decided to find out why the former owner referred to it as the fire breathing dragon. It also appearantly burnt down a shed he had by belching out a fire ball. I rebuild the mag. New sediment bowl and cleaned the carb out. New plugs and wires. 120# compression on all 4 cylinders. Farts and bangs but if you put your hand over the air intake it smoothes out. Has good power. Valves are all set right, timing is spot on. What am I missing here?