2002 WR426 won't stay running once black cold start button is pushed in?

25 replies to this topic
  • james2082

Posted May 14, 2009 - 01:38 PM


The bike will start and run with the black cold start button pulled out. Exhaust turns bright red after about 1 minute? Once I push in the button, it dies. Could one of the jets be blocked? The guy who had the bike prior always ran 100+ octane fuel, since then, I've been putting 93. This is the first time I tried to start up since the winter. Thanks Jim.

  • ww44wrf450f

Posted May 14, 2009 - 02:39 PM


Ya, I'd say give it a bath, and some fresh gas and probably a new plug would help. Thats a long time to run the choke, the plug is probably sooted up, maybe put the new plug in it when you get it to idle properly? The pj. could be clogged, if so just get a new one? or have one on hand? Make shure their's no mouse nest in the airbox or muffler lol.:doh:

  • GCannon

Posted May 14, 2009 - 03:18 PM


Clean the carb!

  • 02WR426Cali

Posted May 14, 2009 - 03:35 PM


Yeah clean the carb and you will probably find some gunk in there from sitting all winter.

  • William1

Posted May 14, 2009 - 04:40 PM


Replace the pilot jet, do not waste your time trying to clean it.

  • matt4x4

Posted May 15, 2009 - 03:24 AM


Replace the pilot jet, do not waste your time trying to clean it.

Easy for you to say! Any idea how much they charge for one of those up here in Canada???

Seriously, spend 2 minutes cleaning it out with a toothbrush, compared to the 20 bucks the dealer wants for a 5mm piece of Brass! :doh: :snore: :lol:

  • William1

Posted May 15, 2009 - 05:35 AM


Unless you have an ultrasonic cleaners, scrubbing does not work 100%. In the US, a pilot is five bucks. The inside and all of thoise tine, precision holes must be perfectly clean, no fine layer of anything. No scraping as you run the risk of enlarging it.

You have no idea how many people swear their pilot is spotless. They soaked it for a month, they scrubbed it. Spent days trying to get the bike right. I spend two minutes putting in a new pilot and off they go.

  • WR_Dave

Posted May 15, 2009 - 06:12 AM


I'm in Canada to so I think your dealer is ripping you off in a big way. I just bought a few pilot jets and they were only $6 bucks apiece. Find a new dealer. WR Dave

  • Woodrider37

Posted May 15, 2009 - 06:54 AM


I had same problem with my 2007 Wr250. You need to clean all jets and house. Best to clean is soak them in Carburater Cleaner for 2 hours then wash them with water. Use air compressor to dry them. Polit jet is not easy to cleaning because it has tiny holes so repeat cleaning or use fine needle to pick the varish. If your area use Ethanol then you will need use additive. My suggest is K100 mg.
Good luck.

  • drtbk4ever

Posted May 15, 2009 - 07:03 AM


I'm in Canada to so I think your dealer is ripping you off in a big way. I just bought a few pilot jets and they were only $6 bucks apiece. Find a new dealer. WR Dave

Hey Matt, Me too. $5 or $6 bucks for jets.

So you guys are telling to stop wasting my time cleaning the pilot jet and just get a new one. Now you tell me. Maybe that explains the stutter while on the pilot circuit. :doh:

Hey James, I would get some fresh gas in there. Drain the old stuff to use in your lawn mower.

Here is a fantastic thread on working on your jets. With photos too.


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  • matt4x4

Posted May 15, 2009 - 09:19 AM


I live in the GTA - they assume we all make 1/4 mil plus :doh: :snore: :lol:
And then they wonder why they go out of business.

We do have some places that will sell them cheaper but you usually have to wait for them to come in, then they ordered the wrong one from parts canada! :banana: :eek: :p :cool:

My brother in law lives in Alberta and he seems to get better prices on everything too, unfortunately - around here, it's a 1 hour drive to get better prices - and with the gas prices the way they are, I'd rather spend a little time with a toothbrush.

  • james2082

Posted May 15, 2009 - 12:50 PM


How do I get the throttle cable off? Does the thottle cable need to be taken off to remove the carb?

  • William1

Posted May 15, 2009 - 02:27 PM


First, loosen the adjuster near the throttle grip oin the bars.
After the cover on the carb is removed, you loosen the lock nuts on the cables, remove them, then work the barrel ends out of the throttle wheel.

  • james2082

Posted May 16, 2009 - 05:27 PM


Guys, after taking the carb apart and cleaning, I found no plugged or blocked jets. Put the bike back together and it is doing the same thing, stalls once I put the black choke back in. It will not run without the choke. I just drained all gas and put brand new 93 octane in it. The previous owner always ran racing fuel or high octane 100 out of the pump. Could the bike be used to this or conditioned and needs this now? 300 miles on bike.

  • byggd

Posted May 16, 2009 - 05:42 PM


Not to insult but are you sure the PJ is completely clear and clean? As william1 stated more often than not you will find it’s the culprit.

  • 02WR426Cali

Posted May 16, 2009 - 07:38 PM


Maybe an accelerator pump problem? Like the diaphram cracked or dried up and got brittle. Just a thought

  • ww44wrf450f

Posted May 17, 2009 - 04:36 AM


You did clean it properly -- right?, and then take a blow gun to all the passages? --- new pj --- float level is correct --- needle is ok (worn or bent) --- the slide is not backwards or was not installed backwards before? I've read that this causes this issue? also check that the boot between the head and carb is not cracked or disformed at the matting surface of the head, be carefull and you can spray a little bit of either at the boot while you got it runnin, but if you do this make sure the motor is dead cold-- no hot header!!! -- get it runnin with choke at idle on it's own and spray a little at the boot, if the rpm goes up, you have a leak? be fn carefull? do this at your own risk? its a snowmobile seal n boot trick!

does the bike start easy when cold, 3 kicks max??

First new pj, you need to elimate this.

is the gasket on the floatbowl -- good?

make sure the slide is properly installed and verified!!!

does the gas from the tank run freely from gas line, not plugged? and or at the air vent?

and yes I am serious about the mouse nest thing in the muffler and or air box?

intake boot is alright?
no leaking at the exhaust flange?

do you know anybody that has a wr426 or 450 and could try his carb?
and was the bike runnin well last year?

let us know how you make out? we are all hoping that you can get it running soon! :doh:

  • james2082

Posted May 19, 2009 - 05:24 PM


Thanks for the response and tips. I recleaned the entire carb, one thing I did was clean the throttle valve and the wheels that attach to the valve and slide up and down. I cleaned out all the grease and re-assembled. Now the throttle sticks!!! The manual says to put fluorochemical grease near these wheels (what kind of grease is this), and do I actually put grease on the wheels that move up and down (there are 4 wheels, a little smaller than a dime). Sorry for these questions but I want to do this correct. Thanks. JIM.

  • William1

Posted May 20, 2009 - 05:11 AM


Carb cleaner will cause the seal on the vacuum release plate to swell and therefore make the slide stick. Once it evaporates, usually, the rubber un-swells.

The grease is for the the actual wheel axles, they specify flourocarbon as it is fuel insoluble.

Did you replace the pilot jet and not merely attempt to clean it?

  • matt4x4

Posted May 20, 2009 - 05:46 AM


By saying you cleaned the carb - you did take everything apart and all the jets out and soak them right? )also take out your choke and hot start and make sure everything is functioning and clean) You checked both diaphrams and cleaned them as well as the passages they feed? You cleaned the AP push rod?
you verified the slide plate is installed correct (it should look like it's installed wrong so be careful).
You can use Molybdenium (moly) grease on those wheels - it's usually dark grey.

Once you have verified that everything is good and you have your idle and fuel screw set to their default positions, put in a new plug, once it fires and runs, you'll need to fine tune the carb once the bike has warmed up.


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