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WR426 auto-decomp - freeze plug, decompression plug and a few Q's

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So, after searching around on TT, it appears that there are 2 methods of sealing off the decompression shaft when converting to the auto-decompression exhaust cam.  

 

The 2 methods are to get a "freeze plug" from an auto parts store, or to buy a decompression plug like this one in the TT store https://www.thumpertalk.com/shop/cart.php?search=decompression+plug&m=search_results .  This plug does not show that it fits the 2001 WR/YZ426, but does it?  Would the #15 plug from a 2003 WR450 fit the same hole? https://www.thumpertalk.com/shop/oem.php?partcategory=871319&manufacturer=7&category=5&year=2003&model=28790

 

Regardless of which method is used, would I need to have the oil seal in place?  #15 on the diagram https://www.thumpertalk.com/shop/oem.php?partcategory=897306&manufacturer=7&category=5&year=2001&model=28895

  • Just read on ThumperFAQ (http://www.thumperfaq.com/) and it sounds like the oil seal is not necessary.  Would still like confirmation.

If I ever sell the bike (unlikely) and the new owner wants to go back to manual decompression for some reason, can freeze plugs be removed? I have never heard of them until today.  Is there any worry about the freeze plug popping out.  That scares me to be honest, and I'd rather spend $20 to have something that physically locks in place, vs a $1 cheap fix.

 

Lastly, which is the preferred cam to purchase (keeping WR timing)...Hotcams or OEM exhaust cam from a WR450, and if there is a preferred year for the OEM cam.

  • ThumperFAQ stated "The 450F cam gear has a different tooth pitch, even though the tooth count is the same.  the new cam will work for a while, but the chain and gear will ahve accelerated wear."  Sounds like Hotcams is the answer.

 

Thanks.

Edited by Pooley

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Hey Pooley. Super good questions, I'm wondering the exact same thing. In fact, I created an account just to reply to this ancient post. Did you ever get your questions answered? I've got a 03 YZ450 cam in the mail and am trying to figure out what to plug the hole with.

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The freeze plug will work with no seal and the plug with bolt should use the seal.

You will be better off with the Hot Cams decompression cam rather than the YZ 450 cam because the pitch of the cam chain is different on the 450 cam chain. the YZ cam does not fit the 426 chain perfect.

I  use both the intake and exhaust hot cam on a ported heat. Works great.

I also left the decomp cable inplace I use it to clear a flooded engine after a crash and the bike has been on its side. Helps get it started quickly without me wasting a lot of energy kicking it

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