bog sometimes?

00 426f stock rejetted for elevation. so here's the deal, been reading a good bit on this and cant seem to nail it down. sometimes its fine on accel others its not. I do a lot of trail riding, and so far this bike has worked pretty well for everything, with the exception of the occasional stall due to operator error. it doesn't seem to matter if I roll on the throttle or just crack it full open sometimes it'll stand right up, other times I get a bog with slower acceleration. here's my question, which mod will work best for this bike? the bk, the o-ring, or the taffy mod to cure the bog completely? thanks in advance

If you read the two mods, the Taffy mod specifically states it is only for the YZ400, and the BK mod is only for the 426.  Before doing either, be sure that the carb is thoroughly clean, and that the pump diaphragm and both pump check balls are in good shape and working right.  Then do the BK to start with.

thanks gray, i'll start with cleaning the carb real well again, and then i'll do the bk mod. appreciate the clarification on the mods.

Pay attention to the part about using a stiff bristle, fine wire, or a number drill on the pilot. 

you could also try a dial jet, it might help with the bogging. It helped on my 03 YZ450. they are like $10

a new pilot was installed about two months ago when I first got this bike, I cleaned the carb out but I would imagine I could've easily missed some crud as the bike had sat for some years with fuel in it. sat long enough for the fuel to completely evaporate, and leave a weird green residue everywhere that was really hard to remove

O-ring mod for sure.  Even with this mod, remember to check the timing of the AP squirt so that it does not hit the slide.  


I still ride my 01 WR426 and the O-ring was the single best performance mod I have done.  My carb is set up like a YZ for jetting and a disabled ACV so it would be identical to yours.  I still use WR timing however. The O-ring mod completely stopped the occasional surge or lean-bog off the bottom.  Which would happen, surge or bog, I could not predict most of the time and was really frustrating.  I had the BK mod for a while, but it really didn't seem to improve things much for me.

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