2002 426 valve check?


6 replies to this topic
  • Ztard

Posted December 28, 2006 - 01:07 PM

#1

Ok so I dug into my YZ for a maint check on the valves....
Almost everything is in spec, below are my findings....
Specs EX.10mm---.15mm
IN .20mm---.25mm
my bike
EX .20mm IN .076mm
EX .20mm IN .10mm
IN .10mm

My question is since I'll be adjusting one of the intake valves, should I adjust everything to the middle of the spec? Or just fix what needs fixing? The bike fires on the 4-5th kick when cold, and 1st kick when hot. The bike runs strong, no complaints. Thanks for any input.

  • Yamahafan

Posted December 28, 2006 - 01:30 PM

#2

Ok so I dug into my YZ for a maint check on the valves....
Almost everything is in spec, below are my findings....
Specs EX.10mm---.15mm
IN .20mm---.25mm
my bike
EX .20mm IN .076mm
EX .20mm IN .10mm
IN .10mm

My question is since I'll be adjusting one of the intake valves, should I adjust everything to the middle of the spec? Or just fix what needs fixing? The bike fires on the 4-5th kick when cold, and 1st kick when hot. The bike runs strong, no complaints. Thanks for any input.


I would only reshim the one intake valve that is out of spec. I believe that the general public can only get shims in .05mm increments, which is why the manual tells you to round the factory shim number (which comes in .01mm increments) to the nearest 5.

Is this your first measurement? It is likely the other 4 may never go out of spec. They obviously haven't moved much in 4 years... which is why you bought a Yamaha in the first place!:confused: :lol:

  • grayracer513

Posted December 28, 2006 - 09:08 PM

#3

I agree. Besides, the one that's out is only out by .001". The other valves were probably set at those specs when the engine was built.

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  • Ztard

Posted December 29, 2006 - 04:15 PM

#4

OK I swapped out the shim, and have everything ready to go back together.... Here's the next question am I at TDC? I have everything lined up as stated in the manual, dots on the cams are lined up with the edge of the cylinder head etc.. But the mark on my rotor is not like the one pictured in the service manual, I'm the 3rd owner so i don't know what has been done beforeI got it. Sorry for the crappy pic best i could do.....


Posted Image

  • yzingin426

Posted December 29, 2006 - 04:27 PM

#5

pull the spark plug and stick a long screwdriver down the plug hole and rest it on the piston, then rotate the crank back and forth until you find TDC. refer to the mark on the crank and you know for sure.

  • grayracer513

Posted December 29, 2006 - 06:07 PM

#6

Here's the next question am I at TDC?

Yes, you are.

  • Ztard

Posted December 29, 2006 - 06:49 PM

#7

pull the spark plug and stick a long screwdriver down the plug hole and rest it on the piston, then rotate the crank back and forth until you find TDC. refer to the mark on the crank and you know for sure.

Thanks, brain on standby...............It's back in one piece. Thanks to all.





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