2004 Wr450 Cam in a 2000 Wr400


5 replies to this topic
  • paul_roca

Posted August 06, 2010 - 11:16 AM

#1

Hi guys

I have a old shot Wr450 engine laying about and im fed up of kicking over my manual de-comp 400 :banana:

I understand the exhaust cam will work in the 400?

What do i need to look out for when timing it up? Is it the same timing as the 400 ?

Any help will be apreciated and pics would be a bonus!

Thanks

Paul

P.S i done a search but most relevant post i could find was a YZ cam not a WR

  • JSanfilippo

Posted August 07, 2010 - 10:09 PM

#2

Grayracer or william1 will likely have the specifics on the cam timing, but you will need a plug for the head where the decompression arm goes.

  • grayracer513

Posted August 08, 2010 - 10:23 AM

#3

I understand the exhaust cam will work in the 400?

What do i need to look out for when timing it up? Is it the same timing as the 400 ?

...i done a search but most relevant post i could find was a YZ cam not a WR

Treat the WR cam the same as if it were the YZ cam in the instructions.

  • Align the crank at TDC
  • Position the INTAKE cam in its normal timing position
  • Set the 450 exhaust cam in place so that it is one tooth farther advanced (rolled forward) than the OEM timing mark would put it.
  • Check that all three shafts are in this alignment when the cam chain is tensioned.

IMPORTANT: If you were working YZ to YZ, there would now be 14 pins of the cam chain between the two punch marks at 12:00 on each cam. Some things I have read regarding older WR's have left me uncertain that this is true of the WR or not. The pin count may be different.

Also, because you will be using a WR cam, the lobe position of the exhaust cam viewed from the right side will appear a bit more upright than the pictures you've seen of the YZ swap.

My advice is this: Remove the spark plug before you start the swap. Before removing the OEM cam, align the engine at TDC and note the position of the exhaust cam lobe. Take a picture if you can. You'll be trying to match that with the new cam.

Once you think you have it right, install the chain tensioner and SLOWLY turn the engine through one cycle (two revolutions) stopping immediately at any sign of resistance. If it turns freely, proceed.

Install the spark plug and check for compression. If you've done things right, the bike will still have a definite compression stroke, but the compression will be about as easy to kick through as the typical 250 2-stroke is. If not, the bike will either have no decompression, and feel like the stock cam, or have so little compression that it can't start.

Use an 18mm freeze plug (core plug, cup plug) from an auto parts store to block off the hole in the head. Dirt cheap solution.

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  • paul_roca

Posted August 08, 2010 - 12:47 PM

#4

Thanks alot for the help, I have installed the cam after alot of messing about. I was keeping the intake cam in its origional position and couldnt seem to get it right. Turns out the intake cam was in the WRONG position! I moved it forward 1 tooth then run the exhaust cam 14 pins away from the first mark. The bike is so much better and delivers power like my 450 now. So the timing must of been wrong in the first place.

The only problem i have is a ticking sound. Obviously a valve clearence issue i just need to find out what size shims i need to get. Do you have any idea?

I have been riding it all day and apart from the ticking sound it has been 100% spot on!

  • JSanfilippo

Posted August 08, 2010 - 02:49 PM

#5

The only problem i have is a ticking sound. Obviously a valve clearence issue i just need to find out what size shims i need to get. Do you have any idea?


Thats one of those deals where you have to measure the clearances to see how far you're off. Its not uncommon to have to adjust valves after a cam swap.

  • grayracer513

Posted August 08, 2010 - 02:54 PM

#6

You have to determine what your current clearances are, then what shims are in place. Then you can do the math to determine which ones you need. There's no way to know without looking, unfortunately.




 
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