Auto de-com cam question

12 replies to this topic
  • woodsk

Posted June 10, 2004 - 03:51 PM


I have had my WR400 for about a while now, I absoutly love the bike. However I am really tired of the de-comp lever. I do most simple maintence on my bike myself, but I am no mechanic. So I do not think I want to jump into changing my exaust cam.

Has anyone had a dealer do this for them? what was the shop cost?

Also what cams would you recomend, the Yamaha cams or an after market company.

Thanks :thumbsup:

  • sabin

Posted June 10, 2004 - 06:08 PM


It's not rocket science. There is a compleate instruction on the yz side. Dave has made great PDF document describing the preaty everithing. I thing it is better to get aftermarket replica of the original wr cam, if it is available. A lot of peapole are using the yz cam to het more hit from the wr, but I'm not a racer and I did not liked this mod. It's just that the bike tires me more quickly. Check out the first post in the yz side and you will find more info than you want :thumbsup:

  • The_Missile

Posted June 10, 2004 - 09:34 PM


It is easier than it seems. Just be methodical and careful.
You should use a torque wrench though on cam shaft housing bolts, so if you dont have one, buy one.

  • tcmII

Posted June 11, 2004 - 09:03 AM


The most important thing to keep in mind from the posts above is the choice of cams: YZ, WR or other. Unlike the non autodecompression cams you will not be able to take a WR cam and re-align it for YZ timing without having an effect on the autodecompression.

Once you pick a cam, have the tools and you are mechanically inclined you should be able to do it. There are a number of posts with PDF instructions that appear to be very good and similar to the original owners manual for cam replacement and shim adjustment.

The only reason I haven't done the swap yet is I don't have much time to ride and want to be able to go on short notice, so I'm saving it for a winter project.

  • galant2nr

Posted June 11, 2004 - 02:16 PM


I did this mod about 6 months ago, and I never thought about it again. There are a lot of advantages besides the loss of the lever. I desert race and the new powerband is great for lifting the front wheel whenever you feel the need.
Everytime I have to start my bike at some lousy sidehill angle, I am glad I can do it while sitting on the bike instead of jumping up and down using the routine...
I did it myself in one evening. If you can change your own sparkplug and oil, you can do this mod...
I bought my cam from for about $106.

  • XR600

Posted June 13, 2004 - 09:39 PM


Have read number of posts around de-comp cam, but most people seem to ride the WR with YZ-timing. Which cam (YZ orWR) should I pick if I have a WR400 with original WR-timing and just want the de-comp feature?


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  • kevs_wr426

Posted June 14, 2004 - 01:12 AM


I went YZ cam and love the thing.

  • yam314

Posted June 14, 2004 - 03:21 AM


The main thing you have to be careful about is the the little half-clip thingy that is sitting in the groove of the camshaft. if you are not careful, it can drop inside of your engine cases and be a real pain to get back out.I have not personally experienced this, but know of people that have.

  • Littlefoot

Posted June 14, 2004 - 05:58 AM


I changed form stock WR timing to the YZ decomp cam. I did not notice any loss of luggability. :thumbsup: This thing can still pull stumps.
I didn't really notice any "hit". It did make the front easier to loft over say a water trap at speed.
I did already have a YZ needle.

I ride tight trails with rocks, roots, water, etc., typical Michigan woods terrain.

  • R_Little

Posted June 14, 2004 - 06:02 AM


Changing the exhaust cam is the same procedure as changing your valve clearance. If you own a WR you are going to need to learn to adjust the valves so do it yourself with a shop manual. Buy a 1/4 drive torque wrench and just take your time. I'm sure you can find a WR auto-cam cheap on TT or Ebay as most guys swith them out to use YZ Cams.

The YZ cam makes the bike more like a 2 stroke, great for everything but tight trails.

  • bcavmechanic

Posted June 18, 2004 - 07:27 AM


I have the hotcams camshafts in my bike and I love the easy starting. I can't say that I really gained any power over the stock cams (at YZ timeing) though.I think If I were to do it again I would just put in the exhaust cam. I let the guys at Hotcams talk me into using both because they said that they work best together to make more power.The only trouble I had was lining up the marks because of the cheesy painted on dots wern't very acurate.I just set them at the most obvious spot. I did have to re-shim all the valves though and it did take a couple of evenings.

  • HotCams

Posted June 18, 2004 - 11:03 AM


Check your PMs. I'm curious what problems that you had with the painted timing marks. Those are put on using a jig, and the chances of being incorrect are slim to none. You should have also seen about a 10% gain in performance. :thumbsup:

  • stevedon

Posted June 19, 2004 - 07:32 PM


I wouold go for the hotcams as it is easy to fit , i did mine in about 2 hours the only bit that takes time is re-shimming. it makes the bike a doddle to start.


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