01 yz426 ISSUES!!! HELP?!

Hey Guys,

I just bought an 01 yz426. Here are the issues I have with it:

-Only runs with the cold start pulled out. As soon as I push it in the bike dies.

-Popping or snapping and flames coming from exhaust.

For performance it has a DR.D full exhaust and a k&n filter. I was thinking the jets are too big and its drowning itself. I know for sure that the MAIN JET is a 180..Is this too big??? I'm not sure what the size of the starter and pilot jet are. I live in AZ and the elevation is 1200 ft w/ and average temp between 80 and 90 F. ANY suggestions would be appreciated!!


Just as a start, have you pulled the carb and cleaned it?

Yeah I pulled the carb the other day. Cleaned out the jets. Everything was already fairly clean. That's when I noticed that it had a 180 main jet..

has the bike sat for a while? mine did the same thing after about 2 month of sitting. i just drained the tank, put in new 94 octane pump fuel and rev'd blipping the throttle until it cleared up (about 1 minute). but b4 that reving part i pulled the valve cover off to insure the timing was still correct because that has never happened b4. i have a big bore kit and cams in the bike and run a 40 pilot 168 main and thats still rich in the summer here in canada (30 deg. C). i dynoed the bike and can run a 165 with no problems, but just to be safe run a bit rich. when i ride indoor tracks around here in the winter (-10 deg C).i just swap the 40 pilot for a 42.

but just by hearing you need the hot start to run the bike hints to me that your pilot/fuel screw is way to rich. and the 180 main i would go back to the stock 162main 42 pilot and fuel screw 1 1/4 turns even with the aftermarket pipe do to your alt.

Thanks for the input! I'm heading to the store tomorrow to pick up a smaller main jet. I really think this thing is running way to rich and drowning itself. I'll let you know how it goes...

If it is too rich, why does using the choke make it run?

The pilot circuit is clogged, or you've assembled the vacuum release plate on the engine side of the slide upside down.

I tried a 168 main and a 42 pilot. It still runs horrible and only with the choke on. Finally decided to take it into the shop today. It's like it has a mind of its own..

what part of AZ. you live?

I live in Gilbert, AZ

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