throttle bog

i just left the 2-stroke ranks & bought a 2000/yz426....i read where the 2001 model has eliminated the bog you get when you blip the throttle from idle.....are there any fixes or bandaids for the 2000,or does this not cause as much of a problem as i think it might during a moto?

read the post "weighting the flywheel"

I had a slight hesitation with my 2000 426. I cured it by going from the stock #162 main jet to a #160 and installed the accelerator pump bottom plate from Factory R&D. It's called the P38. I live and ride in metro New Orleans which is at sea level and quite humid most of the time. My jetting might not work for you.

thanks for the replies.....boit, i will take into consideration your elevation

anyone got a website or email for "Factory R&D"

Nothing in my local dealers catalogues for the p-38



Smitty: When I had ordered the P-38 a few months ago via phone, I asked about a web site and was told that they are working on it. A small ad in Cycle News has only a phone number. 949-206-0894

I fixed my "boggin" by learning to roll the throttle insted of poping. Good luck on fixing it.


I have a 98 YZ400 and it also bogs if you quickly "twist the grip", I was used to this with my TT600, I have been reading the service manual and it states this is NORMAL behavior due to the accelerator pump. I noticed other posts about thumpers trying to remedy this, with nobody really getting rid of it completely.

[This message has been edited by shredder (edited 01-16-2001).]

Really, try rolling instead poping the griper. Its not a 2stroker. If your a poor boy like me you will learn insted of buying a "acc pump". I think thats what boit said.

I don't know why you guys have to roll your throttle on. I can whack mine full open right off idle coming out of a slow tight corner and the response is instantaneous.

Boit, how much did you spend on the acc. pump

bottom plate from r&d?

Thumper426: If I recall correctly, it was $78 U.S., plus about $7 to have it UPS'd to my door. That might sound exorbitant for such a small aluminum plate, but take into consideration a few factors. The company's R&D expense, CNC machining, and whether it works or not. From my perspective, it has been one of the best investments I've made to get my engine to perform as I demand. I can't tolerate an engine that doesn't respond briskly. If I could not have correct this hesitation, I would have sold it to some poor unsuspecting soul and moved on to a different bike model.

Thx for the great info Boit,

I got one on order now.(p-38)

Do you still have the 00 426, what are you running for a clutch assembly?




Did you have to make any changes to the jetting when you installed the P-38 ?

Dennis '99 YZ400F

mine had this same hesitation when I would snap the throttle. I took it down to my dealer here in salt lake and talked to a guy who races for the dealer, he did a couple of adjustments to my vavles and my carb and the blip was gone I have had no trouble with it again. He only charged me $45.00.

Smitty: I installed the Hinson basket, and yes, I still race this bike. I think I might have lucked out and got a "good" one.

DPW: The only other jetting change I made was to go from the stock #162 main jet to a #160. A little fine adjustment on the fuel screw and my carburetion is spot on.

i noticed my 400 bogs right ot the bottom of the rev range.

ive just fitted a white bros exhaust and oddly enough the bogging has all but gone and it seems now not to be stalling when braking or on tight turn.

infact i may now rethink buying a flywheel wieght

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now