accel pump and jetting

O.k. I admit I am new to the bike and racing and have some questions on the whole plug fouling and jetting area. First, going up on the needle seemed to decrease the soot on my plug and help throttle response. Second I am thinking of going to a 168 main jet to head in the same direction (leaner). Additionally if the bike doesn't bog out of corners do I need the accel pump mod. on a 01 426 that was remapped by the dealer to help with fouling, it also has a new cdi and carb.

any help would be appriciated.

I don't know what your main jet is in the bike now. But, I would guess that a 168 would be richer. My 01 came with a 162 stock. It now has a 158 in it. I went with the thrid clip on the needle and 1.5 turns on the fuel screw. This and the major reduction in choke use have cured my fouling problems and gave me a much crisper running bike.

I don't feel I need to do the accelerater pump mod. I may do it just to play, but my bike is running great.



01 YZ426F #85 Vet C


What area are you located, elevation? I'm in New Mexico at about 3500-5000 ft. and I run the stock jetting. Maybe I could go a bit leaner as well though.

I'm in houston Texas. Zero feet 90% humidity.



01 YZ426F #85 Vet C


That is slightly more humidity than we have here :). I guess that contributes to your lean requirements huh.

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