yz 426 questions

1 reply to this topic
  • gsev

Posted June 26, 2010 - 06:40 PM


:thumbsup:I believe i have finally got the problems worked out with my newly acquired 2002 yz426. I have cleaned and rebuilt the carb using a moose brand carb rebuild kit. Main jet 162; pilot jet 42; needle clip position 4 and fuel screw at
1.75; elevation 1200 feet. I think 94 octane, no ethanol gasoline helped as well. Today the bike started on the first kick when cold (it had sat for over a week) and started first kick after about a five mile ride with the hot start botton pulled out. So far I am really pleased with my $1300.00 yz. I have a couple of questions for the guru's.

First, The hot start button will not stay pulled out. It seems that the detent does not hold the button open. Has anyone had this experience? If so what is the easiest fix?

Second, how noise should the top end be? When I first got the bike I pulled the valve cover off and looked at the top end. Everything was extremely clean, cam spockets did not show any wear and the cam chain looked really good. I checked the valve clearance as the manual direct and found that the clearance was exactly the tightest tolerance on each valve. When the bike first starts I hear a ticking noise -- after it warms up it is about the same noise level as my 06 drz 400. Is this about normal?

Third, the bike has an FMF power core 4 exhaust that is in really good shape and very loud. I understand that FMF makes a quite core for this exhaust. If I install the quite core will I need to rejet?

I appreciate this forum -- all of the previous posts has helped sort the bike our thus far, any suggestions to these questions will be appreciated. Thanks in advance


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  • Ryan426

Posted June 27, 2010 - 12:35 PM


Mosly likely you need to re-pack your FMF muff. My 426 was way loud and when I took the muff apart all the paking was gone. When I repacked it it got alot quiter. BTW, you don't have to waste your money on FMF packing. I got rocky mountain's brand of packing for like $7 + shipping. You gotta repack about every 20-25 hrs. I suggest you try the repacking 1st.:)

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