#2 plug continues to foul out

[Guest]

I was cleaning my bike the other day and noticed the #2 exhaust pipe wasnt as hot as the others. I pulled the plug and it was jet black. Smelled the plug and it smelled like fuel. I replaced the plug with a new one and went for a ride. I came back and pulled the plugs and the #2 was the only one that was fouled. All 3 of the other plugs are nice and tan. What would cause the fouling in the #2 cyl and how can I test/fix this?

[tkent02]

A leaking petcock diaphragm will send way too much fuel down the vacuum hose into the #2 carburetor. Pull the hose off and look, it should be dry as a bone in there. If there is any fuel, that's your problem.

[ChicagoBob]

Perforated petcock diaphragm, which draws fuel into the vacuum line when the bike is running. You have the CV carbs, right? and the vacuum line to the petcock comes off #2? A pretty common problem. To test, plug the vacuum line and run the bike with the petcock on Prime.

[DrImodium]

can I safely run the bike on prime until I get a new petcock?

[Steve]

Yes, as long as you remember to turn it back to RUN or RES when you stop the engine.

Just test it before you order the petcock. It's remotely possible that there is a pucker in there that can be straightened out, but a new diaphragm wrapped up in a new petcock is a good idea.

.

[cowboyup3371]

Just remember to turn it off when not using it.