Problem after jetting - YZ426

3 replies to this topic
  • BASSic

Posted March 22, 2008 - 03:41 PM


I just put the JD jet kit on my 01 YZ426 and I have a problem - I CAN'T KEEP THE FRONT WHEEL ON THE GROUND!!!

I complained here once before about how the top end response seemed a bit flat, but after installing JD's kit it's a different animal! Low end power doesn't seem to be much different, but the low end was very good to begin with. I have a Thunder Alley pipe which supposedly gives good low end gains over a stock pipe. The top end is where I really noticed a gain.

Stock main jet was 162S (what's the S for?) and the stock needle was OBEJP with the clip on the fourth groove. Per the JD recommendations, I installed the 170 main with the blue needle, clip in the fourth groove from the top.

My idle is a little strange now. The bike stalled a few times on me while riding, but it's 10 degrees warmer than what I normally have been riding in, and I didn't touch the fuel screw yet. My bike is also backfiring on deceleration now, more than usual. Prior to the JD kit and when I was riding in 30 degree weather, it would pop once or twice, but now it backfires more. Could this be cured by the fuel screw?

I didn't even bother with the O-ring yet because I don't have bog that I can feel.

  • BRYANS01

Posted March 23, 2008 - 07:57 AM


when i put the kit in my bike i used the same settings as you but i put in the small oring and the kit gives you a starting point of 1 1/4 turns out on the fuel screw and i havent had to move it since. If your still popping on decel the yes the fuel screw can help, try going out with it a 1/4 turn at a time and see if it gets better im sure it will quickly. do a serch on here for fuel screw setting you will find a ton of info.

I was just as impressed with the kit, best money ive spend on a mod for sure.

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Posted March 23, 2008 - 07:37 PM


i experiance the terrible anguish of the front wheel not staying on the ground....... when will people begin to learn what we have to go through? when?................

  • jmckinney

Posted March 24, 2008 - 08:00 PM


I went through the same problems with the backfire on decel after the JD Jetting kit was installed. My problems were cured with a differant pilot jet and fuel screw. Sorry I can't tell you if I went up or down but the your local shop should know what to do. Good Luck!

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