2009 yz450 timing

11 replies to this topic
  • walters452

Posted June 14, 2014 - 04:49 AM


Head gasket was leaking so I replaced it, now for life if me I can't get it to start. I've timed it at least 10 times and I get spark from the plug, I'm struggling on this one, I've rebuilt it before and timed it and it ran. Any thing I'm oveookkng ?

  • stevethe

Posted June 14, 2014 - 06:56 AM


Well your heading is timing. If it is off it wont start. You could snap a pic. and post it to be sure. Also or look at a shop manual.

  • walters452

Posted June 14, 2014 - 07:20 AM


I don't have a shop manual, I don't know how to post a pic in here, from what I've seen from other pics and pic of manual I have it rt, mark on flywheel ligns up w mark on case, marks on cam gears long up where they are suppose to b on the head, all I get is backfire

  • stevethe

Posted June 14, 2014 - 07:34 AM



Double check it. Picture is from a WR450 but should be the close to the same. Not sure about the decompression mechanism.

Edited by stevethe, June 14, 2014 - 07:47 AM.

  • walters452

Posted June 14, 2014 - 07:46 AM


Thanks, I've triple and quaduple checked, mine is same as what is in ur pics, all I get is backfire. I rebuilt completely, new crank and piston awhile back and it ran great, just notice I had a oil leak so replaced the head gasket and now won't start

  • stevethe

Posted June 14, 2014 - 07:50 AM


Double check any wires. Got gas or put it on reserve.

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  • walters452

Posted June 14, 2014 - 07:59 AM


Checked wires, it has gas, does not have reserve it's a moto bike

  • stevethe

Posted June 14, 2014 - 08:02 AM


Did you do something or anything to the carb. Any broken hot start nut.

  • walters452

Posted June 14, 2014 - 09:00 AM


Nope, checked everything, thanks for ur help, gonna get a new plug and drain the fuel and out fresh fuel in, I've kicked til my legs worn out all I get is a shot of backfire like I have a exhaust out of time

  • stevethe

Posted June 14, 2014 - 09:18 AM


Good idea. If it sat for a while the pilot jet could be plugged.


Posted June 14, 2014 - 10:28 AM


Did any of your valve shims come out of place?  If so did you put them back in the proper place?

Its also very easy to be 1 tooth off on the exhaust cam on reasembly. The exhaust cam dot will not be straight up like the intake.

Edited by FRANTIK1, June 14, 2014 - 10:33 AM.

  • walters452

Posted June 14, 2014 - 02:28 PM


After puttin it in time a bunch if times and thinkin I was just makin small mistakes I found the problem, it keeps jumping time in the intake side, either I have a bad timin chain adjuster which it seems like it's got plenty of tension but not sure what to look for on that or the cam covers are puttin to much tension on the cams and not letting them turn free enough

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