yz450f timing mark

6 replies to this topic
  • Duane123

Posted December 09, 2014 - 03:08 AM


have a 2003 yz450f and I am currently putting it back together from a blown head gasket, I have the head on and I am now trying to get tdc by lining the line up with the engine cover and as it's about to line up it notches over and will not line up, as it gets to tdc it gets slightly tight then falls past its mark, has anybody had this trouble before, what can be done. Thanks

  • grayracer513

Posted December 09, 2014 - 07:43 AM


If you are rotating the engine with the starter, you'll never get it to stop in the right place.  Put a wrench on the crank and do it that way.  Asa you turn the engine with the spark plug in place, it compresses air in the cylinder.  That pressure will bleed past the rings if you give it a second, then the crank will stay at TDC.  Remember that the crank can turn 3-4 degrees either way and barely move the piston, so it's easy to rotate it off TDC as you work.

  • Duane123

Posted December 09, 2014 - 11:19 AM


Yeh mate i have been turning it over with a wrench on the crank, but I have the spark plug out, should I have it in

Visit the ThumperTalk Store for the lowest prices on motorcycle / ATV parts and accessories - Guaranteed
  • grayracer513

Posted December 09, 2014 - 12:42 PM


With no plug, there should be no tendency for it to roll over the top unless you have the cam lobes pointed down, which would be incorrect.

  • Duane123

Posted December 09, 2014 - 12:45 PM


Well I have no spark plug and no cams in, just the head on and when I crank it to tdc wig a wrench it pops past the tdc mark every time.

  • grayracer513

Posted December 09, 2014 - 06:35 PM


If you feel ANY resistance going over TDC without the plug in or the cams in place, something is wrong. 

  • 72degrees

Posted December 10, 2014 - 03:19 AM


What grayracer said. Or is not so much resistance or a tendency to overshoot TDC. Is it possible the flywheel weight momentum keeps it moving? - I suppose not.  Have you also tested for TDC with a probe through the plug hole? I preferred to do it that way and turn the motor by having it in top gear and nudging the wheel round - not an option until the motor is back in naturally ;)

Related Content


Is it worth it? (Cam and High compression piston) by macgi77

Dirt Bike   Make / Model Specific   Honda   CRF 150/230 F/L
  • Hot  36 replies

The "going back to the other darkside" adventure... by Monk

Dirt Bike   Make / Model Specific   KTM   250/350/450/505 SX-F & XC-F (4-Strokes)
  • Hot  113 replies

Thinking about Yamaha 250... by Arctic Pride

Dirt Bike   Special Interest Forums   Pro Racing
  • Hot  491 replies

Megabomb Fitment by 288yz450

Dirt Bike   Make / Model Specific   Yamaha   YZ 400/426/450
  • 1 reply

Yamaha YZ450F 2017 by Chris.GVS

Yamaha YZ450F 2017
  • * * * * *
  • 1 review
  • Last review by Tommyk_55
  • On January 15, 2017

Join Our Community!

Even if you don't want to post, registered members get access to tools that make finding & following the good stuff easier.

If you enjoyed reading about "" here in the ThumperTalk archive, you'll LOVE our community. Come join ThumperTalk today!

The views and opinions expressed on this page are strictly those of the author, and have not been reviewed or approved by ThumperTalk.