2001 YZ426 Valve Lifter


3 replies to this topic
  • YZ Yankee

Posted September 10, 2015 - 08:24 AM

#1

Hi, was working on valve cleance and a piston and ring change.
Just noticed I have 2 valve lifers with a blue dot, 2 with a black dot and 1 with no dot.
Per the manual, the dots should be the same.

Will this make a difference?
Thanks.

  • grayracer513

Posted September 10, 2015 - 08:44 AM

#2

The dots indicate alternate size diameters for precisely fitting into the lifter bores at the factory during assembly.  The differences are very small, in the range of 0.0001" or so.  Usually, with a used head, it doesn't much matter, but best practice when disassembling the head in the first place is to be certain that each valve and lifter are identified as to which hole they came from, and get put back in the same spot. 

 

The size range runs, I'm pretty sure, from smallest to largest, yellow, black, then blue, with black being the "standard" size.  When in doubt in the case that one needs to be replaced, use the black.



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  • YZ Yankee

Posted September 10, 2015 - 10:10 AM

#3

The dots indicate alternate size diameters for precisely fitting into the lifter bores at the factory during assembly. The differences are very small, in the range of 0.0001" or so. Usually, with a used head, it doesn't much matter, but best practice when disassembling the head in the first place is to be certain that each valve and lifter are identified as to which hole they came from, and get put back in the same spot.

The size range runs, I'm pretty sure, from smallest to largest, yellow, black, then blue, with black being the "standard" size. When in doubt in the case that one needs to be replaced, use the black.


I may have lost track which lifter came from which valve..
ie. The two exhaust valves clearances measured the same and have the same shims under them.
So you think it'll make a difference if they go on the one not on originally?
Also, one lifter has no markings.
Thanks.

  • grayracer513

Posted September 10, 2015 - 01:08 PM

#4

If you end up swapping the exhaust lifters left for right, you may find the clearance will change.  In fact, it's likely that it will.  Not a big problem, but it can be annoying.

 

Also, in spite of the fact that it doesn't always do so, be sure to check the valve clearance after the head is fully torqued in place.  Some who set up their clearances with the head on the bench are surprised to find them wrong after installation.







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