#4 cylinder fouls sparkplug after i ride for awhile turn it off and start up after awhile. all the jets in carb are tight and clean.what might cause this besides bad valves. only #4 is doing it???

 

the sparkplug itself
change it

 

He stated only #4 is doing it, as in more than once... right? Have you had the carbs adjusted/tuned? Sounds like #4 carb is running a little too rich.

 

Sunk float, misadjusted float, bad or clogged float needle and/or seat, or sticky diaphram slide that is hanging open. You could check the compression to see if the rings and valves are good. You could also check the resistance of the spark plug wires, but if the spark plug is firing, it's probably the carb, since number 1 and 4 cylinders share the same coil.

 

t

 

its happend more than once. i checked the coil and wire and those are good. could it be the air screws can that cause it.if so where in carb are they.the people that did my jet kit didn't plug regulater back in but if that was it wouldn' all carbs. do it??