2004 WR450 cam timing -- what have they done to this bike?


8 replies to this topic
  • DeepPurplishBlue

Posted February 25, 2014 - 10:54 AM

#1

Got a good deal on a 2004 WR450 that is extremely difficult to start.   e-start is out of the question

and my foot still hurts from attempts to light it with the kickstarter, which was successful only

twice.  Not just that it is hard to start, it is extremely hard to kick...  as in excessive compression.

 

Guy that sold it wasn't the original owner and said he thought the exhaust cam had been "changed

to be like YZ450"     So, that sounded to me like someone monkey around with the cam timing.

 

When the bike is running it idles nicely and seems to run OK but we can't have these starting

issues so I popped the valve cover off to take a look.   What I found makes no sense...

 

What you see in the picture is with the mark on the rotor aligned at top dead center, cam lobes

pointing away from each other.

 

None of the marks on the cams align with the edge of the head, and I count 15 pins between marks... 

Yikes! No wonder this thing is so hard to start!   What were they thinking?  If moving it one pin is

good, two pins must be better?     Not only that but the overall timing is wrong now as well.

 

Planning to set it back to proper factory timing but this is a new low for bad, misguided "performance

mods"    ugh...

 

 

cams.jpg



  • grayracer513

Posted February 25, 2014 - 02:33 PM

#2

Let's start by recognizing that counting the pins between the cams' 12:00 o'clock marks IS NOT how cams are timed.  The pin count thing is useful only as an assembly aid, and as a secondary cross check method. 

 

Then, it would be nice to know whether those were original WR cams, or where they might have originated.  Currently, it's timed with the intake 22 degrees retarded and the exhaust 22degrees advanced.  Very odd, and apart from the fact that advancing the cam that much will greatly increase the cranking compression, retarding the intake by that much would hardly make the bike more willing to run. 

 

What do the lobe positions look like from the right side in this position?



  • DeepPurplishBlue

Posted February 25, 2014 - 03:05 PM

#3

Let's start by recognizing that counting the pins between the cams' 12:00 o'clock marks IS NOT how cams are timed.  The pin count thing is useful only as an assembly aid, and as a secondary cross check method. 

 

Then, it would be nice to know whether those were original WR cams, or where they might have originated.  Currently, it's timed with the intake 22 degrees retarded and the exhaust 22degrees advanced.  Very odd, and apart from the fact that advancing the cam that much will greatly increase the cranking compression, retarding the intake by that much would hardly make the bike more willing to run. 

 

What do the lobe positions look like from the right side in this position?

 

 

Well, yes, I am aware counting the pins is not the way to set the timing.  I was mentioning that as a conversation point because that

is what people that try to "set the exhaust cam to YZ timing" are following.  

 

I did not take a picture of the lobes, but they were fairly flat with respect to the edge of the head rather than pointing slightly up

as should be expected.

 

I am expecting they are the original WR cams since the bike is pretty much unmolested from stock but no way to be sure.



  • flyandride

Posted February 25, 2014 - 07:15 PM

#4

Here's what the cams should look like, stock cams in stock position.  I've highlighted the alignment marks with yellow dots to show up better. 

 

Also, in your picture it looks like the chain is either loose or kinked.  Looking at the pins in the chain between the cams.  450stockcams.jpg



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  • DeepPurplishBlue

Posted February 25, 2014 - 07:46 PM

#5

Here's what the cams should look like, stock cams in stock position.  I've highlighted the alignment marks with yellow dots to show up better. 

 

Also, in your picture it looks like the chain is either loose or kinked.  Looking at the pins in the chain between the cams.  attachicon.gif450stockcams.jpg

 

 

Yea, that is what it looks like now after fixing it...     still scratching my head wondering what they were thinking changing

it to how it was...    :excuseme:

 

Planning to change the chain later after I get this sorted out.



  • grayracer513

Posted February 26, 2014 - 07:33 AM

#6


Also, in your picture it looks like the chain is either loose or kinked.  Looking at the pins in the chain between the cams.  

 

...Which may be how it got to be the way that it is.  Kinking, binding timing chains are a primary cause of these engines jumping time.  The tensioner is designed only to remove true slack, not to press out the kinks in a sticky chain.



  • DeepPurplishBlue

Posted February 26, 2014 - 07:49 AM

#7

...Which may be how it got to be the way that it is.  Kinking, binding timing chains are a primary cause of these engines jumping time.  The tensioner is designed only to remove true slack, not to press out the kinks in a sticky chain.

 

 

That is my thought as well, but one cam moved forward and the other backwards...    seems unlikely for a chain jump but stranger things have happened...



  • grayracer513

Posted February 26, 2014 - 08:03 AM

#8

Didn't happen at the same time.  A kinked chain will jump the sprocket that is farthest from the driving load.  With the engine turning forward, that would be the intake cam.  If the engine kicks back a little on startup, or bounces off compression on shutdown, the exhaust will jump.  Lucky it was only one tooth.



  • mebgardner

Posted February 28, 2014 - 11:40 AM

#9

That is my thought as well, but one cam moved forward and the other backwards...    seems unlikely for a chain jump but stranger things have happened...

 

May I request you re-post your original picture?  The link is broke when I attempt to look at it.

 

I've never seen this condition, it would give me a leg up for future reference...

 

Thanks.






 
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