Fouling Rear Plug in '06 SJ

[x2skier]

My 2006 SJ has not skipped a beat this whole season until this weekend. I went through 5 different plugs on the rear cylinder from fouling. I would get about 20 minutes of riding time before it would completely foul again. So far I have cut the plug wires back, replaced the OEM plug caps and swapped the front and rear wires. None of this helped; still fouling the rear cylinder only. Could it be a carb issue?

Here's the setup:
62T / 61X Big Bore
ADA Head
OEM ignition with MSD Enhancer
OEM dual 44s

 

[WILKEY]

runnin to rich

 

[x2skier]

double post

 

[x2skier]

Riight, but why all of a sudden after 15 tanks of fuel on the same plugs and zero adjustments to anything is it now running rich........and only the rear cylinder?

 

[Polish jet pilot]

You should be checking your plugs for color more often - vibration and other harsh conditions do not help the carbs at all - take a fresha pair of plugs and ride it for 10 min - stop the motor and check plugs - should be nice brown/tan color (the darker the more premix you have burning) - if the plugs look wet (you are running rich - safe - but losing performance and fouling plugs...)

 

[SUPERTUNE]

Go through the carbs and see if anythings wrong...go ahead and replace the needle valves too, as they cause this problem when they start to leak and go bad.

 

[wrxman60]

yo weren't kidding man, everytime I saw you out there on Saturday at Corson's, you were heading back to the ramp running on one cylinder, what is your premix ratio?