Fouling Plugs

I have a 2002 400ex completely stock, it started to foul plugs 3 days after I got it. My buddy bought one the same day and he is having the same problem, We have had the bikes 3 weeks and are both on our 4th plugs. The dealer said it would stop after they broke in. WRONG!! then he told us it was because we were choking too much, ??? I have read the other threads on fouled plugs, and some people have mentioned using higher octane gas, I run 89. any suggestions?

use 92 octane, It helped me out. YOu should also check to see if it's running to rich.

[Guy400]

BS, take it back and asked that it be fixed. If they don't, DEMAND that it be fixed. Most dealerships jet the bikes when they uncrate and prep them. Maybe they got the jetting a little fat. This is especially odd considering your friend has the same problem. The only way you'd foul plugs constantly was if you were riding with the choke always on in which case the bike would richen way up and then stall. If you're only using the choke to initially start the bike then there should be no reason that it's fouling plugs on a consistent basis.

You may want to try removing your airbox lid and see if that helps. That may lean it back out just enough to counteract the overrich state you might be experiencing.

My dealer said to just run regular 87 octane. I got my ex home and read the little manual they supply and it said run at least 92 octane. I don't know if this is your prob with fouled plugs but I would run premium and do what guy660 suggested about taking it back to the dealer if you can't figure out why it's fouling.
John
One more thing, choke is all the way up, then there's a half way, and choke off is all the way down.