Originally Posted by
rapidroy
Hey buddy, one old goat to another here, you mentioned going through the fuel system when you first acquired the machine.
Did you perhaps change the fuel pump? These are relatively low pressure pumps approx. 3 psi, if say a 6 psi pump is installed it will lift the float needle and permit excess fuel in the manifold which will richen up the fuel mixture. A rich fuel mixture is akin to driving around with the choke pulled on which could possibly foul the spark plug in one or both cylinders. RR
PS; just noticed you mentioned it is original fuel pump, oh well maybe previous owner changed it or the pressure relief failed, would not hurt to check fuel pressure at the carb just in case...