99 wr400f help please

Well i got rid of all my carb problems. BUT the problem persists, Fuel flow is not the issue and the carb is sparkling clean! It seems to do just fine then all of a sudden cut out it even revs pretty well. Any ideas guys??? thanks


One other question, anyone live in san diego that might be able to help me out in person? Im just at a loss to what to do next?? I live in Carlsbad thanks guys


I'm in San Diego, Lemon Grove area.

I had a similar problem with my WR400 when I first got it and it was a loose wire on the CDI. It still seems like carb problems to me though.

My 2000 pilot jet is extremely sensitive and it will not run unless perfect. I have to take it out and clean it with a single strand of a throttle cable unraveled. Once this is done it is like a new bike. Did you do that or just dip it and use spray cleaner on it? that will not do crap. I know some say dont use a wire but sharing what has worked and worked well. Without that jet clean this bike is crippled.

Let me try to clean the jet again just to see! Ill look at the CDI too thanks for the tip! I was wondering it couldn't be a problem with the TPS sensor could it? would that effect idol and what would happen if i unplug it? thanks guys!


TPS sensor wouldn't cause those issues. I have run without my hooked up for a while. Keep messing with the carb, a buddy of mine had a YZ400 that wouldn't idle and we cleaned the carb three times before we got it right. Sounds like you're close!

gotcha! SHOOT i was hoping youd just say unplug the darn thing! Ive taken the carb off about 15 times (given i am TOTALLY new to this) Im gonna give it a go in a bit and maybe i can take some pics! thanks !

mine does exactly the same so your not alone.

I have cleaned all the jets and checked float and was sticking.

Anyone suggestions on what to use on the float to stop from sticking.

When cold it starts first kick but when warmed up it just dies and have to wait till cold again before it will fire back up

Ya please if anyone knows let me know im STILL pulling my hair out over this!!!

I think the float assembly comes comes as one piece that includes the valve and everything and just pops in. Either order a new one or clean the valve and seat. Do you have a manual?

When cold it starts first kick but when warmed up it just dies and have to wait till cold again before it will fire back up

Sounds like your choke is stuck.......

what kind of breather hose you have on your tank?

Try running with just a piece of hose - no other connectors on it.

checked your spark plug wire for continuity at different temp levels? Could be a break in the wire that spreads as it heats up and separates.

Mine only ever quit like that once and wouldn't fire again for the life of it - ended up the plug died.

Ill check both of those things thanks guys! I did have an idea could all this be caused by my intake valve being too tight??? thanks guys


Very well could be caused by tight valves, as they heat up they will get tighter and may eventually not close at all until they cool. However, this is also usually accompanied by a hard start when cold. Valve clearance and timing would definitely be worth checking even if you weren't having problems. Easy to do, and you may even consider replacing the timing chain while you are in there with this bike being so old. If you need help with that we can sure give that as well. Hope this helps.


one last carb thought the oring around the float valve seat looked pretty tired, could a defective float valve seat be causing that problem?? thanks again guys for all this help it really has made a world of difference and ive learned so much, i cant ask for a better community of people!


float valve seat stops fuel from entering bowl when full, if leaking your bike would dribble fuel out the overflow line.

But the bike will continue to run since the jets are submersed inside the fuel in the bowl anyways so it really doesn't care about it being 1/8th higher in the level....

valve clearances??tight maybe

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