2001 YZ 426 Starting issues

6 replies to this topic

Posted December 01, 2008 - 06:57 PM


Hey, my friend has a 2002 YZ 426 and he`s having major starting issues with it. It hasnt had any maintenance done to it (as far as timing chain / re-build etc.) done to it, but anyway heres what he says its doing

"It wont start, i havent tryed it lately, but i was havin` trouble, it would fire up and i`d go riding, it would run good, i would shut it off every now and then, but near end of day sometimes would be a real pain to start. I would pull the plug clean it a bit and it would fire up again"

any thoughts?

  • 642MX

Posted December 01, 2008 - 07:34 PM


Check the valves first.

  • cmore

Posted December 01, 2008 - 10:05 PM


I had that same problem on a WR 426 I was running it way to fat , ( to much fuel), 4 strokes can way leaner & never hurt it. I would look @ your jetting.
Bring your needle down 1. & If you changed your main jet bring it back to stock. I run 600/1000ft sea level. trail only not much on the main jet. As I live in MI USA

Hey a 2002 is 450, I also have yz426 never much changed jetting for the weather

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  • grayracer513

Posted December 01, 2008 - 11:20 PM


Hey a 2002 is 450,

No, it's a 426.

98-99 YZ400

00-02 YZ426

03 up YZ450

  • 1998YZ400F

Posted December 02, 2008 - 07:46 AM


i wouldnt just jump into making the jetting leaner right off the bat. i would check it and see what it currently is and go from there. but i would recommend a good thorough cleaning of the carb. i would also check the valve clearances. once you get all of that right, they are easy to start.


Posted December 02, 2008 - 07:46 AM


ok thanks, ill let him know

  • motojoe_23

Posted December 03, 2008 - 12:40 PM


on a bike that old, a good carb cleaning can make all the difference in thw world. It could be any number of things though. As stated valves is one possibility. Also the accelerator pump could be "off" for any number of reasons. Clean it up, check the accelerator pump, check the carb boots (although they usually make it leaner if they leak), check the exhaust pipe and packing, check the valves, and THEN check the jetting is what I would do

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