2002 YZ426 Poor Mid-Range

3 replies to this topic
  • JoeBoss

Posted May 26, 2002 - 05:36 PM


Somebody please give me some tips on main jet and pilot jet and pilot settings for my 2002 YZ426... it has very poor mid-range. I live in Orange County, California, if this helps any... my 2000 YZ426's mid-range ran excellent, now I don't know what's up. Pilot jet is stock, pilot screw settings is 1 1/2 and main jet setting is up from 162 to 165, tends to run better with 165, but tstill not where I'd like it. Love some help if anyone has ran into this or can solve. Thanks.

  • Guest_mxrider426_*

Posted May 26, 2002 - 07:18 PM


Try adjusting the needle clip position. The needle adjusts the mid range, while the pilot and screw are for the bottom, and the main is for the top. I would check my float level. Mine was set wrong from the factory. If it is off, it can mess up your jetting.

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  • JoeBoss

Posted May 26, 2002 - 07:22 PM


Thanks for the tip, I'll check it out... the float sounds more appropiate than the needle... tired the needle, wasn't helping, thanks though.

  • Boit

Posted May 26, 2002 - 07:54 PM


What exactly do you mean by the poor mid-range? Does the power fall off once you get into the mid-range or is there a response issue? The more specific you can be, the easier it might be to zero in on your problem.

mxrider426 makes a valid point about the float level. However, there is also something to keep in mind about overall jetting. Changing the pilot jet affects the main circuit since fuel ALWAYS flows through the pilot jet. Think about that for a moment. If you were to increase the pilot jet by one step, it has a small enrichening affect throughout the entire range. Sometimes, making a pilot jet change will also allow a fine tuning on the main jet. Changing the clip postion affects how soon or how late the transistion is made from the pilot circuit into the main circuit. Perhaps the thing to do is to experiment with different pilot jets and clip positions. Also, some guys have had tremendous success with different needles, especially the next leaner needle.

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