I own a 1979 low rider 1200 bored out to a 1340, it is a great bike.The problem is the rear cylinders plug fouls out on a regular basis. It is a custom bike with exhaust pipes that are a bit larger in diameter than original pipes. I have been told that if I have a carb jet replacement that it will correct the problem. If anyone is `an expert on this matter please let me know if that is correct. Thanks.. Jeff K.