2000 WR choke problems


I just picked up a WR400 and it is having the infamous won't run without the choke on problems. I was told the carb needed to be cleaned when i bought it and so far i have come across a few things. The throttle slide was in upside down, didn't fix the issue. The pilot jet was sorta plugged, i soaked it in the ultra sonic and it looked brand new again but didn't fix the issue. The only other thing i can think of is the "mixture screw" (i think thats what it is called) does not have an o-ring on it, it looks like it is supposed to in the parts diagram. Will this cause problems? Other than this stuff i am open to suggestions, its killing that i bought the bike but can't ride it:bonk:



that could be a part of your problem. by the sounds of it, you completely tore apart the carb and made sure it is all clean - did you blow out all internal passages? Sometimes, crud blocks the actual passages in the carb, not just the jets.

Is your float set up right?

Did you check for air leaks where the carb and cylinder meet?

When you said the trottle plate was upside down - you made SURE right? Because it's proper position makes it look like it's upside down.

You're running fresh gas and a new plug correct?

I only use Shell 91 octane (has no ethanol) - I find my bike runs very well on it.

Where in Ontario are you located?

Buy a new pilot jet.

I put the throttle plate in with the little hole and half-moon cut out to the bottom, like it shows in the parts diagram. I blew out the carb with compressed air and it seems really clean. The pilot jet i let soak in the ultrasonic cleaner for about 10 min, and that gets just about everything imaginable out of it. I have fresh gas but i have not tried a new plug. Does anyone know where i can get that tiny o-ring that's not from yamaha? Its very, very pricey. Matt4x4 i am in Ottawa.



I would shine a light up in the mixture screw passage and see if that o-ring is jammed up in there, that could be your problem. You can buy the o-ring, spring and washer from www.jdjetting.com or I'm sure you could find just the o-ring on thumpertalk.

Thumpertalk has that o-ring for $1.21, part number 3TJ-14562-40-00 . That's for an 07 WR so you may want to cross reference it to make sure it works but I'm sure the fuel mixture screw setup hasn't changed. And yes that oring is important.

Thanks guys it was the o-ring, swapped one in from another bike and have one on order.

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