03 yz 450f Valve seating, ? @ timing chain pin count ?

7 replies to this topic
  • TimKade

Posted October 31, 2014 - 03:45 AM


Replacing all 5 valve's in the bike... Will I need to use a seating compound to seat them to the head ?


Also   On the 12;00 Cam marks... How many  Timing chain   ( pin's )  is there between the  two marks ?

  • grayracer513

Posted October 31, 2014 - 06:53 AM


Absolutely NEVER use lapping compound on any titanium valve, ever.  It can seriously degrade the hard coat on the valve face.  The seats have to be professionally refinished by a machine shop.



Regarding the pin count: http://www.thumperta...t/#entry6331731

  • TimKade

Posted October 31, 2014 - 07:27 AM


THANK'S Gray..

  • TimKade

Posted October 31, 2014 - 12:54 PM


Untitled-1.jpg Untitled-1.jpg Sorry guy's.. But I'm not at all a mechanic... Gray the bike I'm working on , is the same bike that you helped Nathan Stiltner with...I
got it before it got lined out... In your post's to him.. 13 pins between the 12 o'clock marks.. and I went to the link you r me. and
really didn't get my mind clear on what to do.. SORRY.. And then I found this print. and now im even more confused..   there's 14 pins on that print

Edited by TimKade, October 31, 2014 - 12:59 PM.

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  • TimKade

Posted October 31, 2014 - 12:55 PM


there's 14 pin's on that  print

Edited by TimKade, October 31, 2014 - 12:55 PM.

  • grayracer513

Posted October 31, 2014 - 01:25 PM


The pin count, as I said in the link I posted is only valuable as a cross check and an aid to assembly.  IT IS NOT the way cams are timed in a YZF.  That function falls to the timing marks alone.  With the piston at TDC (top dead center), the timing marks are to be lined up with the head as shown.


The pin count will vary from one model group to the next.  Most of the 250's are 12, a lot of 400's and early 426's, along with certain WR's will have 14, while most426's and 450's are 13.  If you're going to make use of them at all, you need to know what the right count for yours was to begin with.


The marks will not line up perfectly.  They aren't even stamped perfectly.  Old worn cam chains make that worse.  When they don't, the question to ask yourself is whether they will be closer to lining up if moved a tooth one way or other, as in the picture below:



  • TimKade

Posted October 31, 2014 - 03:07 PM



  • TimKade

Posted October 31, 2014 - 11:12 PM


The bike is Starting first kick now... it was jumping time , from backlashing ..... guide was worn and bent... Thanks Gray

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