WR 400 stalling

HI guys, just joined the forums hello to all...

Bought myself a 1998 WR400 2weeks ago, the rear suspension appeared to be seized, the speedo didnt work, it wouldn idle, front disc is bent, has no rear blinkers & a very loud exhaust, picked it up cheap as a result but otherwise it is quite good has had a fresh top end.

Everything has been sorted through apart from the idle, i pulled the carby down cleaned every jet put it back together and it will now idle but stalls after a while and is diff amount of time every time. Pulled the Pilot and Main jet back out, they'r both factory pilot is #45 and main is #165 yesturday i bought a #48 #168 to replace them as it has a full exhaust which is a quite a big one, im unsure whether it is because the bike is lean that it stalls or because the tps is not plugged in, when i plug the tps in it idles far too high and stalls eventually anyway.

Im having trouble adjusting the TPS going to give it another go today but can the TPS cause the bike to stall if not plugged in or is it totally unrelated as they obviously run on a 2d map without tps so i cant see that it would cause the stalling but i am probably wrong?

Have you tried a new plug?

Sometimes, the old plug shows it's faults as it starts to warm up.

Also, the old plug should give you an indication of rich or lean, from where you can better adjust your jetting.

Don't just start changing your jets on a whim, you should really ride the bike to hear what the bike is doing - it's easy to tell by ear whether you're running lean or not.

Sometimes the problem also lies in a dirty carb, if the bike was rough, I'd expect the carb to be filthy and coated in varnish.

Adjusting the TPS is pretty simple but you need a OHM meter. If you have the Clymer book on this it give some straight forward guidance.

Thanks for the replies :eek:

Basically the first thing i did was clean the carby out thoroughly, now the trouble i was having was stalling and backfiring as i backed off, in order to stop it backfiring i had to wind out the mixture 4 times, this made me think the pilot jet was not big enough so i thought id step up to a #48, basically my reasoning for the #168 on the main was that the carby was stock but the exhaust was huge and the plug was slightly white tinged, so i though 1 step up on pilot and main maybe a good idea. My query is whether the TPS can cause the bike to stall because i know they run a 2d map without the tps plugged in which says to me it should be fine and wont stall, so i can then assume its a fueling issue. In the process of buying new jets i lost my starter jet (someone moved the parts on me) now im waiting for the bike shop to order one in it should be in today so im yet to try the bike with the bigger pilot & main. As far as adjusting the tps i think best way would be to get 2 pins and stick them through the wires then hook the multimeter up with aligator clips and adjust from there, somehow i think i will have to stuff around alot because i have adjusted the TPS in all angles with the bike running and it doesnt help so im thinking it will be right out and i will have to pull the carby out, its a pity i cant adjust the TPS without the engine running, it such a exhaust and my neighbourhood doesnt agree with it, annoying.

Hmmm... Yep, sounds like your on the right track in tweaking the carb. If you get in touch w/ Ed Sisneros AKA burned at the jetting forum he can probably help you get your jetting dialed in.

After reading your response about the TPS it makes me wonder if your checking the correct side of the TPS connector. You should be checking the carb side (male side). The pins should be pretty easy to hook your aligator clips on to. I'm not sure why you would need the additonal pins to attach your clips too:confused: I'm also not sure that you go to alternate mapping by having it unhooked. As far as I know the only way to get to the alternate map(yz timing) is to lift ground to the CDI by diconnecting the grey wire. From what I understand you can start and idle w/ the TPS off but you'll get backfire etc.. trying to run without it because the TPS is not advancing the timing as you turn the throttle...or something like that:excuseme: Anywho, aside from being within your adjustment parameters you want to see nice smooth movement on your ohm meter as you move the throttle wheel. Any thing else and the TPS is junk.

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