Fouling Plug

[luv2valk]

Hello everyone. I have a plug on the number 6 cylinder that keeps fouling. My first time noticing that it was not running right I thought that I may have gotten some bad gas so I added about a half bottle of Sea-Foam to a nearly full tank but nothing changed. After doing a plug check all of the plugs looked great, especially with 78,000 miles on them except for the number 6 plug. Looking at the ends of the Cobra 6-6 pipes read the same thing, all of the ends were clean expect the one that lead from the same cylinder.

I've adjusted the valve lash on all cylinders and put in a new set of plugs but nothing changed. I've also added the second half of the bottle of Sea-Foam on my second fill after running nearly a full tank though, tapped on the carb float bowl with a hammer and opened up the drain screw and nothing has helped. The spark plug is getting fire as I have pulled the plug, started the engine and ground the plug to the side of the engine and it's getting plenty of spark. I've been at speed and been able to pull the wire off the plug and there is a noticeable drop in power so I know that it's trying to light the fuel but it seems like there's just way too much fuel for it to burn.

I've also checked for any loose hoses and it appears that the intake boot is secured to the air box. The air filter (K&N) was cleaned a few month ago. I wonder if it may be a stuck float but I wanted to run it though this board to see if anyone else has had a similar experience and could pass on some information before I start tearing into it.

Any help is much appreciated!

[timmer]

Could be a small tear in the petco*k diaphram which allows gasoline to be pulled into the #6 Cylinder through the vacuum line connected between the two. That is what caused the same problem for me this spring.

timmer

[Challenger]

Long shot here, but the vac line for the petcock is hooked to the #6 intake runner, if the diaphram is leaking it will suck in raw fuel to #6 cylinder and would more than likely foul a plug, (ok) I see Timmer beat me the keyboard

[timmer]

Great minds think a like challenger!

[luv2valk]

Thanks guys for the tip, I will look at that before tearing the carb apart. Is the diaphragm inside the petcock?

[NITRO]

Thanks guys for the tip, I will look at that before tearing the carb apart. Is the diaphragm inside the petcock?

Yes, you will need the petcock rebuild kit to fix it.

[luv2valk]

Just a followup. I ordered the rebuild kit from HLD which came in the mail yesterday. I tore the petcock apart and the diaphragm was torn big time. I installed the new one, reassembled everything plus cleaned the plug and went for a ride and no more miss. It felt good to get back on the bike,it had been a week which is was too long. Thanks for everyone's help!

[Challenger]

Glad you got rolling with just a rebuild and new spark plug. could have been much worse.