2002 426 running hot

[zaxcar1]

just got a 02 426f just jumped the 2 stroke ship. when i start it cold it stalls. have to restart it 4 times then play with the throttle to keep it running. and when it idles the front pipe gets red hot. once i am moving it goes back to normal. the bike runs great when i am riding, but like i said she dont like to idle. o and the last owner told me that the carb was gummed up and he cleaned it the best he could. i do have the clymer book. o and does any one know good carb mods? i have been looking at zip tye racing. are they any good?

[tmckeown]

It is normal that headerpipe will get cherry red. None of Yamaha 4-strokes like to idle. They just get hot fast. Any fuelscrew that you can adjust without tools is a big help. There are several threads about jetting, so just use search.

Timo McKeown

[SJMC_DON]

All of my WR's have always idle'd just fine:excuseme:

You might be real lean, make sure the hot start is not stuck partially open. This will cause the bike to run SUPER lean... otherwise it might just be jetting set up. You can search the forums but there is jetting forum that will help inclusive of model year, elevation, various mods etc...

TM is right, if left to idle long enuf all WR/YZ's will get hot and the header will glow red but it should take a good 3-5 minutes of idle'ing.

[zaxcar1]

well i got the bowl off, and found the pilot jet was gummed shut. so i am gonna try and clean it.

[maxtherat]

soak the jet in some carb cleaner and use a piece of wire from a wire brush to clean. Blow out with air. WR's should idle well, but the pipe will glow within 30 secs. Ride it at night, if it still glows while moving then go richer on the needle.

[ninthrazor]

It is normal that headerpipe will get cherry red. None of Yamaha 4-strokes like to idle. They just get hot fast. Any fuelscrew that you can adjust without tools is a big help. There are several threads about jetting, so just use search.

Timo McKeown

I have a 2000 426 and it idles beautifully. When i start my bike cold, it will usually kick over on the second kick. I run it on the choke for about 30 seconds then kill the choke.I let it idle for about 2-3 minutes, then i give it throttle.

I have found that if I simply "crack" the throttle it will die every time (this is normal with the Yamaha 4-stroke machines). However, if i don't simpyl "crack" the throttle, but rather I give it quite a bit (about 1/4 - 1/2 throttle) it does just fine.

The 426 is a mean machine, i will give it that. She runs great and never given me a second of doubts!

[Alternative]

When I got my '02 426 it ran like ?. I pulled the carb and stripped it down completely and gave everything a good clean. Put it back together, put a JD jetting kit in it and now runs perfect. If you found the pilot jet clogged I would pull the whole thing apart to make sure all the fuel ways are clear and everything is working as it should, then jet it properly and everything should be sweeeet .

[matt4x4]

My Wr400F is exactly the same - starts on first kick, just don't blip it until it's warm, header glows if standing - needs the airflow to cool it, honda's are the same with the glowing header, probably others as well.

Roll the throttle on slow and it won't stall.

In the summer, you can pretty much start it and go within seconds, in the fall when it's cooler, you notice the difference in warmup that is needed.

[Birdy426]

While you have the carb apart, might want to concider the Air Cut Valve mod and the BK mod or JD O-Ring mod. See ThumperFAQ for the BK and ACV mods and search the CRF forum for red beard's o-ring mod...

[Team_Oatmeal_Pie]

Make sure to dump the gas you have in the tank and then take a look inside with a flash light, its amazing what bad gas can turn into. And you dont want to take all that time to clean the carb and run bad gas thru it again. As it will mostly likely run fine for one ride, but then the next ride start acting up again. I learned my lesson.