Carb Question 99 WR400

Right off idle there is a glitch with this carb, it hickups and acts if it is not getting any fuel. Everywhere else it is fine. The bike is stock except for free mods, I don't believe this to be purely a jetting issue(could it be TPS, air jet etc.), it is an annoyance when trying to ride very slow speeds. We've cleaned the carb, adjusted the fuel screw several times, tried different pilots etc. Any suggestions.........TW

Hey TW.

I have a '99 WR400 with this problem also. If you have cleaned the routine crud buildup out of accelerator pump bowl, then try searcing for the "Taffy RC collar accelerator pump mod" in the TT archives. This mod involves mounting a tiny radio-controlled model wheel collar onto the acc. pump shaft. Set the shaft movement for 0.32 (+ -) and tighten the little allen key down. This will restrict the amount of "acc pump squirt" into the engine on initial throttling.

I would also HIGHLY SUGGEST replacing the timing chain on the bike. As the chain wears and stretches, your timing gets worse and worse. This timing error may be a significant part of the bog problem.

Hope this helps.


Thanks Jeff, I'll give it a try, if only I had my old 99 back to do a quic carb switch it would have made life simpler :thumbsup:............TW

Check carb slide also

drop the needle once and if ok drop it again. that should be the start. if you want to go further i would drop the MJ to a 165 maximum. by now it should come good.


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