'03 Yz450 Won't Start After Adjusting Valves

4 replies to this topic

Posted May 26, 2006 - 12:56 PM


I have an 03 yz 450 and i adjusted the valves on it. well when i put it back together it went exactly the same as when i took apart, the cam timing marks lined up, piston is at top dead center. went to start wont fire but shoots flames out the exhaust. How many degrees timing change is it if i happened to be off a tooth by chance? will it even start if its off a tooth on the cam? Whats the best way to re-time the bike?

  • grayracer513

Posted May 26, 2006 - 02:37 PM


One tooth is 22.5 degrees. Depending on whic cam is off and in which direction, it will either start or not start. Or bend the valves.

I'm not sure what you mean by "retime the back", but the only way to retime either cam is to remove and reposition the cam.

If you neglected to reset the cam chain tensioner before you kicked it over, the engine probably slipped time in a big way, and you may have some serious trouble on your hands.

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Posted May 26, 2006 - 03:23 PM


i meant re-time the bike sorry. is there a way to completly start the timing process over from scratch so i dont bend a valve?


Posted May 26, 2006 - 03:49 PM


just had same problem with mine was off one tooth it would not start at all.to retime remove cams put piston back at top dead center make sure to keep tension on timing chain so it dont jump a tooth on crank gear.follow manual on setting cam timing.turn over by hand a couple times so if it binds up you wont break anything.take your time i did this a few times before i done it right

  • MathProf

Posted May 26, 2006 - 04:19 PM


I also was one tooth off the last time I reassembled my top-end.

Don't sweat it. Take it apart. Check that the pointy part of your cam lobes are pointing toward the front(exhaust) and back(intake) of the engine and that the timing mark is lined up on the flywheel..

Then line up the marks on the cam sprockets with the top of the cylinder.

Requires no Brain.

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