spark plug fouling when cold

2 replies to this topic
  • sirthumpalot

Posted August 24, 2001 - 03:36 PM


I Just fouled my second plug and the only thing that I can contribute it to is starting the bike (to show a friend :) ) and letting it run for only about 30 seconds and turning it off without ever fully warming up. The next time I tried to start it, no fire. Not even a sputter. Put in a new plug and it fired right up. Never fouled one while it was running (yet). Has anyone else seen this particular problem? This is an '01 and otherwise has run flawlessly.

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  • jaybird67k

Posted August 24, 2001 - 04:52 PM


If it is only fouling on start up, then pull the header and look for a carbon build up in your ehaust port and in the header it self.
I had the same problem with a new 01 426 and jetting did not help, but after explaining my problem to BK(Tim Ferries engine mech)he said this is a classic example of carbon build up which holds moisture in the cylinder causing the plug to short out.
He suggested running race fuel, and since I did I have been on the same plug every since.
# 67

  • sirthumpalot

Posted August 24, 2001 - 04:59 PM


It must have been shorting because after I put a new plug in it I hit the old plug with some throttle body cleaner that I had in the garage (spray can) and then put it in the plug cap for an old yz80 that I have in the garage and it got a nice blue spark. I haven't tried it in the 426 yet but I'm wondering if this is all that is needed to save a plug?

I'm going to try to avoid removing the header if I don't have to for sake of time (I don't have much to spare these days). If it keeps doing this then I guess I will pull the header and check, but the bike has so few hours on it that I cannot believe that there would be a significant amount of carbon in there yet (still on the stock chain!). Thanks for the tip though. :)

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