WR Carb. Problems

I had just purchased an 02 WR426. I have been doing some reading on mods for this bike, and I have done just a few of them. I cut down the throttle stop, cut open the air cleaner lid and put a FMF powercore 4 exhaust on. Now the problem. The bike is street legal and I have not had a chance to take it out in the dirt as of yet, but I did ride it around town. So far it starts fine, even when warm, but if you back off of throttle it stats a little back firing and at idle if you snap throttle it will try to die. If you have RPM's up in nuetral and left off throttle it will cough and die. This is my first four stroke, so my first thought is air/fuel mixture. adjust air screw first before playing with any jetting. If this is correct, any suggestions as to where to start with screw turns.

Thank you all.

P.S. I live in the Arizona Desert 300 Ft. A.S.L. if this should help. :banghead:

sounds lean from all of the uncorking you did.

probably needs a full rejet, but try backing out the fuel screw a half turn...see what that does.

have to agree, sounds lean. what are your needle and clip settings?

I would assume stock, because I just purchased the bike about a month ago, and I was told it was stock, but you know how that goes, never assume right. I will try to check out what my jetts are in the next few days. Thank you. I don't want to sound stupid and all, but on this bike I do need to pull the carb off to check the jetts?? Can't just turn the carb to access float bowl like on older bikes??

Again thanks

I have pretty good luck with loosening both boots, and working the front boot off...leaving the intake boot on...and pushing the carb toward the left side of the bike. Gives you sufficient access to the bowl, and the needle.

It sounds lean to me. A quick check would be to turn on the cold start knob (choke) while you are riding in 2nd or 3rd gear and see if the poping goes away. If it goes away richening the jetting will fix the problem.

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