New to me '05 YZ450 valves



30 replies to this topic
  • 72degrees

Posted April 04, 2014 - 04:41 AM

#21

I'll confess I got mine one tooth out on the exhaust cam at the first re-assembly attempt after shimming. Take your time and double check TDC and cam wheel marks after the tensioner goes back on then re-check clearances. It's a wonderful moment when it bursts in to life again first kick :)



  • Outlaw45

Posted April 05, 2014 - 12:46 PM

#22

Ok changed shims, bolted down cams, and installed chain tensioner. 

 

Rotated flywheel to look for correct "I" mark.  Yes I see that now, before I was lined up on the dimple.  When I lined up the "I" mark the cams were pointing in towards each other, I rotated the flywheel around one more time and then they pointed out.  Like this.

IMAG0569_zpssqtp8wxu.jpg

 

IMAG0570_zpsubu2qqnr.jpg

 

IMAG0572_zpsm3rp3oen.jpg

 

IMAG0574_zpsqxmnsxhc.jpg

 

Is this the way its supposed to be?  I checked clearances again.  Both exhaust valves are 0.203mm.  Intake is 0.152, 0, and 0.229  I'm going to leave the exhaust and just change out the two intake shims 0 and .229.  The .152 intake clearance is right at the limit.   

 

How am I doing?  I'd like to thank all of your for your help and input.

 

Rob



  • Outlaw45

Posted April 05, 2014 - 03:44 PM

#23

I'll confess I got mine one tooth out on the exhaust cam at the first re-assembly attempt after shimming. Take your time and double check TDC and cam wheel marks after the tensioner goes back on then re-check clearances. It's a wonderful moment when it bursts in to life again first kick :)


How did you know you were a tooth off? What did it do?

  • Hoosier-Daddy

Posted April 05, 2014 - 06:48 PM

#24

How did you know you were a tooth off? What did it do?

Should be 13 cam chain pins between the 12 o clock marks on cams at tdc.
I jog mine around by hand after everything including tensioner is put back together. Then recheck.

  • 72degrees

Posted April 06, 2014 - 11:16 AM

#25

It wouldn't start! Just one big backfire in the muffler. Then I re-checked it with the aid of brighter light and strong reading glasses (my rheumy old eyes at fault again!)  and could see the exhaust cam wheel mark was not lined up perfectly at TDC. My mistake was not to check it after putting back the (manual) tensioner. That 13 pin tip is useful !

 

It survived without damage and started instantly once correctly set up.

 

It was going very well today and took my lad to 6th in an NHCA Top Ten run off in awful horizontal rain conditions.

 

Your photos look right to me now but best get an expert opinion from Greyracer.



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  • grayracer513

Posted April 06, 2014 - 04:47 PM

#26

Ok changed shims, bolted down cams, and installed chain tensioner. 

 

Rotated flywheel to look for correct "I" mark.  Yes I see that now, before I was lined up on the dimple.  When I lined up the "I" mark the cams were pointing in towards each other, I rotated the flywheel around one more time and then they pointed out.  Like this. 

 

How am I doing?  I'd like to thank all of your for your help and input.

 

That's how they should look.



  • Outlaw45

Posted April 07, 2014 - 08:55 PM

#27

Grayracer,

 

Do the cam indictors look TDC or do they look like they could be one tooth off?  Intake one tooth the rear and exhaust one tooth to the front?  But then the lobes would point up more.

 

Also, I have 13 chain pins between the the indicators on the cams.  Is it important if there is more chain on either side of the flywheel, between the cam and flywheel?


Edited by Outlaw45, April 07, 2014 - 09:04 PM.


  • grayracer513

Posted April 08, 2014 - 06:53 AM

#28

The only thing that matters is that the crank is at TDC, aligned with the mark, and that the cam sprocket timing marks at 9:00 on the exhaust and at 3:00 on the intake line up.  The pin count between cams is irrelevant, and only useful as an aid to assembly and as a double check. 

 

Obviously, there is more chain on the back side run than on the front.  The chain goes around the tensioner shoe on the back.

 

As I already said, they look right now.



  • Outlaw45

Posted April 08, 2014 - 12:19 PM

#29

Thanks, never done any engine work of any kind and was a little nervous I in over my head and would screw something up. Everyone here has been very helpful.

Rob



  • Outlaw45

Posted April 10, 2014 - 11:27 PM

#30

I think I finally got it.  I had to remove the intake cam three times before getting it right.  What a pain, at least I know how to do now. 

 

Intake clearance spec is .10~.15mm. 

 

My clearance is .15mm.  It's on the high side.  If it's not in the middle like .13, is it better to be closer to the low side .10 or the high side .15? 



  • grayracer513

Posted April 11, 2014 - 12:03 PM

#31

The tight limit is the ideal, but realize that the whole specified range is only .002" from tight to loose, so in the end, it doesn't make too much difference.







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