I'm in, but need help

Off the 2 stroke and on the 4 stroke. I just picked up a 99 wr400 last saturday. I got a deal on it as it will not idle. I took a chance that it is something simple. The bike has been sitting for 5 months and fired up first kick but will not idle. Sounds to me like the pilot jet circuit, I cleaned it out but no good. I will also check the throttle shaft adjustment. I checked the tps setting also, all looks good. The bike will let out a couple of backfires out the carb when bringing it down to an idle then dies. Any other ideas as I have done the search thing. The bike only has 1638 kms.


I could be way off here, but I've seen earlier post of same description. Accel pump dirty, clogged jetts, even carb slide in upside down as both ends look closely alike during disassembly. Spark plug?


Carb slide first!!!

(been there done that)

Make sure your clear what we are talking about

so you can make sure


Definitely check the carb slide and the valve clearance as well.

Steve T

Thanks for the replies..I checked the valve clearances all within spec. I can get this bike idling now sort of...What happens is when I bring down to an idle it will stay at fast idle like the choke is on, (I definetly know that the slide is all the way back down) then about 5 sec later the engine will drop down to the proper idle. The carb slide plate looks good ( no cracks). Do these carb slides tend to wear out and leak air through the sides?

lets be clear about this carb slide.

if you pull the whole slide out you'll find a plate that comes loose. it must have the 1.5mm "arch at the bottom.

check for free movement of the carb slide. the idle knob should be 4-5 turns out from closed.

make sure that you have cable slack.

make sure that the carb has the float height det at 9mm, make sure you have the piece of plastic that clips onto the MJ area.

have you pulled out the two air jets in the pillbox slit and blown them out?

you may have an air leak somewhere, so how does it run higher up the revs etc?


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