YZ Cam Timing

10 replies to this topic
  • chinesespaceman

Posted January 13, 2007 - 09:42 AM


Hi Guys,

Just been in to check the valve clearances and found what I suspect to be YZ cam timing mod has been done. However, when I set the flywheel to TDC (with the lobes facing away from each other) the inlet cam mark is about 2mm below the cylinder head / cam cover joint face. Is this likely to cause a problem?

I have attached some pics, one shot from a higher angle to show the dot on the inlet cam and one shot from level with the joint face, where the dot cannot be seen.

There is 12 pins between the camshaft marks along the top chain run.

The TDC mark I am using is nthe I mark which is about 10mm after the H mark on the flywheel so I believe to be the correct mark.

The bike runs okay, but I use only for Enduro, mostly low and mid range work - will the bike be better if put back to standard WR timing for my riding?

The bike has completely standard exhaust and airbox cover. I don't believe the UK buikes have the grey wire? Please advise.

Anyway, I would appreciate your comments, and will leave the bike disassembled until I get some feedback.



P.S. When I click to add picture it asks for a URL? How do I attach pictures please

  • old man dan

Posted January 13, 2007 - 10:24 AM


What year is the bike?

  • chinesespaceman

Posted January 13, 2007 - 01:53 PM


Hi Dan,

Thanks for responding.............
I was led to believe the bike was 1999, but when I bought rear pads the '98 ones fitted, so guess probably 1998



  • Fullbore4

Posted January 13, 2007 - 02:05 PM


for yz timing, looking from right hand side at the cams, when crank is at TDC, the exhaust cam lobe will be a little higher than the intake lobe....for wr timing, the lobes are exactly the same angle pointed outward and up....I would leave it as yz timing because these bikes run better timed that way......my 2 cents.

  • old man dan

Posted January 13, 2007 - 02:07 PM


It sounds like you have YZ timing, get a manual and verify. There are a couple of online sources for the manual, search here. The YZ timing is more aggressive and I prefer the WR timing for low speed stuff. Its pretty easy to change back and forth so try it each way and make up your own mind.

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  • chinesespaceman

Posted January 13, 2007 - 03:08 PM


Thanks guys,

I'm certain it is YZ timing, just concerned that the inlet cam TDC mark is slightly below the joint face when crank at TDC, ie the inlet timing is retarded.

Is this a big issue or fairly normal?

I will check the tensioner tomorrow.

The chain does not seem overly taught between the cam sprockets, I wonder if the tensioner is a bit lazy, or if the chain might be stretched.

If antone knows how I can post photos this would make clear



  • Fullbore4

Posted January 13, 2007 - 03:26 PM


Go to this site and upload pics and then post the links here. Its free.


  • chinesespaceman

Posted January 14, 2007 - 08:25 AM


Okay, here are the pics of the cam wheels when the crank is aligned at TDC. The shot showing the timing mark on the inlet cam sprocket is taken from a higher angle, as the dot is actually below the face of the cylinder head .

So from these, can anyone suggest why the inlet sprocket does not align when the crank is at TDC? Could it be the sprocket has slipped on the camshaft?
Or is it more likely problem with tensioner or chain?



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  • Fullbore4

Posted January 14, 2007 - 08:38 AM


I downloaded those pics and brightened em up so I could see the index marks and I'm not sure about that old of bike but on mine TDC is the 3rd mark on the flywheel when turning the engine to TDC. It appears to me you need to turn the engine a bit more to get actual TDC and then the dots will align with the case. You can verify top dead center by putting a straw down the spark plug hole and carefully seeing what TDC is I would think. Sorry I'm not much help.

On second thought, if timed per yz the dots will not align. I'm as confused as you.

  • trueblue426

Posted January 15, 2007 - 04:57 PM


thats definetly yz timing....count the chain pins between the top index marks...12 yz...13 wr looks just like mine:thumbsup:

  • trueblue426

Posted January 15, 2007 - 05:02 PM


haha i guess i didnt really answer the real question there. it looks right by my recolection but to be sure go to the sticky thread in this forum there is a procedure for timing with alot of good pictures you can compare with


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