??? for 04 yz450f for those that have rebuilt their engines.........

2 replies to this topic
  • qkenuf4u

Posted March 03, 2007 - 05:50 PM


im rebuilding a guys 04 yz450f engine (crank seized to rod)
. i have the manual but i cant seem to get the balancer to match whats in the book. if ya have the manual look at page 4-64 and youll see what im talking about.
they have the special notch/dot on the gears/shafts so you cant put them on wrong but mine isnt matching up to what the manual says it should.
if i align the dots im just past TDC on the crank and my balancer weight is at the bottom of the circle. if i swing the rod to BDC the balancer weight is now at the top. they say in the book im supposed to have the balancer center line in line with the crank centerline and theres no way.
any help would be great. hope to have him up and running by wednesday.

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  • grayracer513

Posted March 03, 2007 - 07:47 PM


The crank gear can only go on the splines in one place because of the key spline. Likewise, the splines on the balancer are also keyed to prevent the gear being mispositioned on the balancer shaft. If you install the gears so that they fit onto the shafts, and the timing marks align, they're on right.

The top picture on 4-64 and the associated note telling you to align the balancer shaft in that particular manner has only to do with inserting the shaft into the cases, since there is a flat cut into one side of the shaft so that it clears the crank as you slide into place, and it has to be in that position to insert it. It has nothing to do with timing it.

The bottom two pictures on 4-64 do not show the gear in the position it would be in if the dots were aligned, so don't go by that. The balancer weight will be in the opposite position of that of the crank pin at any given moment.

  • qkenuf4u

Posted March 04, 2007 - 06:07 AM


THANK YOU !!! that makes sense but wanted to be 100% sure. :applause: :lol:

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