Hi,Rob! Along with what the others said,I've got a feeling you may have an air restriction or too rich mixture.(That's if they're fouling)You didn't say what was wrong with the plugs(how they failed). If they're blistering the porcelain electrode sleeve or melting at the tip,you might have a too-lean mixture or air intake leak.Man,that is really hard on a spark plug and can burn your piston! If your spark is weak to the plug you'll get fouling also.BYE!