someone pleas help. after a days ride, i let the bike sit in the garage. it isnt cold outide, about 55-65 at night. and the next day the plug is fouled. the hgas wasnt left on, i dont twist the throttle when its off, and im jetted right with a 165 main! this is the 3rd plug ive fouled in 3 days! someone PLEASE help me as im about to smash my 01' 426 to pieces with a baseball bat! BTW, ive already cut the blue ignition wire!

Welcome to the club. I went through 15 or so plugs and two trips to the dealer, one bottle of Prozac and 15 cases of beer to get mine running good.

This is what worked for me, fine tuning of the carb and I drop the main way down to 158 runs great.Been on the same plug for three weeks. :)

try this: when done riding, turn fuel off and let it idle for about 25 seconds, just let it idle. dont touch throttle. then kill it. put it away. then lets say you want to ride it tomorrow....turn the gas on, turn the choke on, put your right hand on the master cylinder and then go through the drill

ill try those ideas. thanks alot, i dunno how much hair i woulda ripped off my head or how many times i woulda pushed my bike off the stand onto the cement if i didnt have TT to turn to.

I started having the same exact problem on my '01 as you're having. In my case the solution was to change brands of gas, but different solutions seem to work for different people. Hope this helps..

Had the same feeling. Mine's an '02 and started to foul a plug after every ride, also started a minor poping (more than normal) on decel. This is what fixed it for me. I cleaned the carb, made special attention to the pilot. Leaned out the pilot/air screw 3/4 turn. Cleaned and made sure all of the connections/rubber boots between the intake, carb and airbox were tight and not leaking air. They I took off the exhaust and used high temp sealant between the motor and head pipe, and between the head pipe and silencer. That solve my problems for now, knock on wood. I was reading a lot in the red forum to see if they had this many problems, thought about converting. I'm glad I have it going smooth now, love it when it's running good. Good luck.

Hey all you guys, one more thing. Make sure you oil level is right. Ive herd of guys fouling plugs when they shut off their bikes. It sounds crazy but if you have too much oil in your bike, when you shut it off the oil gets sucked back up into the cylinder some how and fouls the plug real quick! Just a tought check your oil WHEN THE BIKE IS WARMED UP!!!!

Don't run oxygenated gas if it is in your area.

Check your float bowl level.

Other than proper jetting, these two things were killing my plugs. Now everything is fine.

My first suggestion would be float level. Me thinks the 01's got a bad batch of carbs from Keihen.


I would first clean the carb, especially the pilot jet (and the hole it comes out of) and the fuel screw hole. Be sure to get the air jets.

Then I would reduce the fuel screw until it ran slightly bad and leave it there. If down to 1/2 turn out before that happens, a smaller pilot and do it again.

Then I would suspect my ignition. If you have a buddy with a 250F/426F, swap coils and CDI with him.

Good luck,


It took a new coil and running VP 100 octane on my 01' for it to finally run right but know I can get months on the same plug and runs great!

my bike was doing the same is what you need to do. put a 42 pilot in it , it will run great. I have had the same plug in it for a month. let me know how it does

I have found that letting the bike idle before shut down, coupled with using my DR. D. Hotstart until it quits works well--much like "cleaning the plug" on a 2 stroke. It leans out the mixture and burns the crap off of the plug.

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