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bob426

02 YZ426 PLEASE help!!!

13 posts in this topic

Just bought a 02 YZ426. It will only start and run with the hot start knob pulled out. (even when starting cold, have to use hot start). It runs well with the knob out, but it will not run well or idle without the knob pulled. If I push it back in it runs very choppy, won't idle, and backfires a lot. What should I do?? Any help greatly appreciated!

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Adjust the idle. Then go to the jetting forum and it will tell you how to adjust the fuel screw on it. That should help. As far as I know the hot start lets more air in the mixture so your setting might be too rich. Look at your fuel screw underneath the carb. count the turns to turn it all the way in. Stock settings are 1.5 turns out. DO NOT ride the bike with the hot start out. You can do some damage.

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If you've had the carb apart recently (or if the previous owner had it apart) make sure the metal plate in the carb slide isn't in upside down... it looks right when it's upside down and does exactly what you are describing.

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PROBLEM: ritch....

pull the plug....tell us what collor...is the choke on?? :thumbsup:

what fuel using??? fresh???

if all else fails, plop the bottem of the carb, buy a manual....adjust float to factory specs...and yes, try the jetting fourm.

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Just bought a 02 YZ426. It will only start and run with the hot start knob pulled out. (even when starting cold, have to use hot start). It runs well with the knob out, but it will not run well or idle without the knob pulled. If I push it back in it runs very choppy, won't idle, and backfires a lot. What should I do?? Any help greatly appreciated!

I have the exact same symptoms ('01 426) you describe with one difference. I have to use the choke to keep it running at all instead of the hot start like you describe. I'm still troubleshooting the problem and I'll pass along any info I find. Any suggestions out there would be appreciated.

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I had the exact same problem, ran well with the choke out. I did everything imaginable. I tinkered until I was having nightmares. In the end, it turned out to be an exhaust leak at the header pipe where it met the muffler. I was sure it was tight as I wrenched on it. On a hunch, after another failed attempt at jetting, I unbolted the exhaust muffler from the frame mounts, and to my amazement, I was able to slide the muffler off without undoing the flange. This meant I had an exhaust leak. I installed a new gasket and problem was solved, though it did run rich until I put everything back to where I started from...Lesson learned? Start with the simplist and most basic cure for any problems. Spark, fuel and air leaks...If it isn't there then start digging..

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I had the exact same problem, ran well with the choke out. I did everything imaginable. I tinkered until I was having nightmares. In the end, it turned out to be an exhaust leak at the header pipe where it met the muffler. I was sure it was tight as I wrenched on it. On a hunch, after another failed attempt at jetting, I unbolted the exhaust muffler from the frame mounts, and to my amazement, I was able to slide the muffler off without undoing the flange. This meant I had an exhaust leak. I installed a new gasket and problem was solved, though it did run rich until I put everything back to where I started from...Lesson learned? Start with the simplist and most basic cure for any problems. Spark, fuel and air leaks...If it isn't there then start digging..

That may be my problem. I noticed last time I put my exhaust back on it fit a little loose. It's a slip on WB R4 and the clamp is tight but maybe the gasket is damaged.

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Yea if you are like me, I was switching back and forth from spark arrester and closed course exhaust. Unfortunately those fiber type gasgets are not made for frequent changes. It was the best 15 dollar fix I have made, I only wished I made it earlier.

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Pull the rag out from inside the air filter. Some of us have made that mistake :thumbsup::thumbsup:

Lol that happened to my friend once. He couldn't figure out what was wrong, he kicked until he was blue in the face and even tried to pull start it using a strap and a truck. Finally him and his bro just sat down and all of the sudden his bro says dude when we changed your air filter did we take out the rag? and then they just started laughing

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Check your timing to make sure it didn't jump a tooth, mine did and it caused it to idle badly and backfire like CrAzY, luckily i stopped right away and it didn't do any permanent damage so i just replaced the cam chain. it might not be the problem but timing isn't something you want to take lightly so i would check it out. good luck man :busted:

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