2002 wr426 engine cutting out when the throttle is cracked

2002 wr426 bike runs ok all the way through unless you crack the throttle then it just cuts out and stays like that if you keep it held open. As soon as you let off just a little bit it takes off. Right now I have stock carb accept a 170 main, white bros tapered pipe, R4 silencer, yz cam timing, bk mod, and the air box lid off. I have tried 48 pilot, and adjusting the air screw. I have tried adjusting the accelarator pump all the way to shut off. None of this has changed a thing to keep it from cutting out. If anyone has a good idea of what might be wrong I would really appreciate your help.

It sounds like you are bogging when you whack it. That sounds like a rich condition to me (way rich)

Whats your altitude? After you are coming down off high revs does the bike backfire (gunshot) or sputter alot or a bit?

If you come down of revs and it backfires then I would say lean it out across the board until you get what you are looking for.

If it just pops a lot then you would be lean, maybe more on the pilot than the main. Hence go up a bit.

My best guess is raise or lower your needle. Raise needle/lower clip = richen up Lower needle/Raise clip = Lean.

I would check the above on the jetting ques before you go any farther but, I would bet you are rich and you are going to be able to fix it by raising and lowering the needle, or, replacing your current needle with a leaner one.

JMHO

Race

If you come down of revs and it backfires then I would say lean it out across the board until you get what you are looking for.

If it just pops a lot then you would be lean, maybe more on the pilot than the main. Hence go up a bit.

I'm the worst to ask about jetting, but I thought it was the other way around. Popping = rich, backfire=lean. I'm probably wrong so please correct me. :)

Go back to the stock pilot. Way to much there and you are flooding the motor!

Then do a search on the BK carb mod. Also a ZipTyracing fuel screw is worth every penny!

What is the main benefit of the Zip Ty Fuel screw. Do you have to adjust the mixture that much on these bikes????? At around $22 the Zip Ty set-up is definitely cheap enough. :)

thanks alot but I tried moving my clip up one but it didn't help it from dieing when you wack it. other than that it seems to run fine no backfiring or poping when you let off the gas. I'm in ohio and it's only 40 degrees out but it still shouldn't do that right?

The bog can be caused by either to rich or to lean. Set the squirt to start as early as possible without hitting the carb. slide. Set the squirt durration at less that one second. Spend $65.00, order the JD Jetting kit from the TT Store. Use the jetting in my signature and have a blast. :)

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