01' plug fouling question


My '01 426 has recently begun fouling plugs.. but only during the first cold start of the day. And then only after I start the bike and let it idle without riding it, then shut it off and leave it for a few days. After doing this on the very next cold start it will fire a few times then foul the plug and die. Drop in a new plug and it starts and runs great. Of you who have delt with this already and fixed the problem with a new CDI, what did the bike behave like before and after the new CDI? I'm not convinced that it's a CDI problem but I'm ready to start looking into it.

I'm at sea level with 100% stock jetting, the bike runs flawlessly and starts easily once I get it started for the day.


I had the same problem on a 4 month old 01 426 and according to Brian Kinney this is a carbon build up problem holding moisture in the combustion chamber causing the plug to short.

One quick way to find out is to just pull your header pipe and look in it and your exhaust port for build up, if its there clean it, and then go to a quality fuel and you'll have no more cold foul problems.

My plugs burn white now that I went to race fuel, after BK's recommendation.

Hope this helps..............Later.


You've mentioned checking the header before and I'm gonig to have to try it. But first I'm going to take your idea on changing gasoline brands. Now that I think back I didn't have the problem until I started using the gasoline from a specific name brand gas station. I'll change brands and if that does the trick then I'll post the brand that wasn't working for me. Thanks for the idea!!

I have to agree with the fuel recommendation, running a mix of 92 pump and VP 108 (1:1 ratio) cured my fouling problems and now coupled with performing the BK mod on my carb my 426 nows runs like I always thought it should!

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