Auto Decompression


8 replies to this topic
  • Nathanael

Posted July 22, 2008 - 12:12 PM

#1

I am looking to add auto decompression to my 02 426, and I've found several options...two have me confused though. They appear to be the same thing, and I don't know for sure if they even include auto decompression (because it says exhaust cams are separate and that they include auto decompression).

Here they are:
http://www.hotcamsin...w&productid=488

and

http://www.hotcamsin...w&productid=483

They appear to be identical except for price...any help here?

  • CAVSCOUT96

Posted July 22, 2008 - 03:47 PM

#2

the first one is the one you need.

OR

get the OEM '03 YZ or WR EXHAUST cam

  • Nathanael

Posted July 22, 2008 - 04:34 PM

#3

So the first one includes the auto decompression mechanism? What's the difference between what I posted and the exhaust cam you mentioned?

Sorry if I'm newb at this...never really modded motorcycles before.

  • husqvarnarider

Posted July 22, 2008 - 05:01 PM

#4

The first one is the exhaust cam, second is the intake. From what I understand, the 03 yz/wr cam has a slightly different chain pitch, but still works. The hot cams is specifically made for the application. Someone will correct me if I'm wrong on that.............

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  • CAVSCOUT96

Posted July 22, 2008 - 05:37 PM

#5

The auto-decomp is the small, spring-loaded, cam on the end of the exhaust cam in the picture. You'll note if you look closely that the intake cam does not have it.

The simplified explaination is that as the piston moves through its stroke and reaches close to Top Dead Center (TDC) the kicker gets very difficult to move because of all of the compression built up in the cyclinder. The auto-decomp allows the exhaust valve to open and relieve the built-up pressure so that you can continue to push the kickstarter / electric starter. The intake cam/valves have no role in allowing the starter to complete it's mission. That's why you ONLY need the Exhaust cam to make the conversion. If you want more performance at the same time... Replace BOTH cams with the HOTCAMs. If you JUST want Auto-Decomp.... by an '03 WR OR YZ EXHAUST cam.

Here is the link for the YZ exhaust Cam from TT store:

http://oem.thumperta...5TA-12180-00-00

$112.00

  • Nathanael

Posted July 22, 2008 - 06:59 PM

#6

Awesome, thanks for the replies!

  • maxtherat

Posted July 22, 2008 - 07:28 PM

#7

The first one is the exhaust cam, second is the intake. From what I understand, the 03 yz/wr cam has a slightly different chain pitch, but still works. The hot cams is specifically made for the application. Someone will correct me if I'm wrong on that.............


Correct the 03 cam gear does have a slightly different pitch. If you are curious then retard the timing on your current cam and see if you like the power difference. Weather you like it or not then you can decide what cam to buy. Remember that the hotcams is for both the yz and the wr and the timing is the same for both bikes. If you get a yamaha cam then you get to pick between the YZ or WR. I'd suggest the hotcams just because it will be easy for you to set the cam correctly.. Remember to check your valves once complete; don't assume that it will be the same.

  • wakemaker

Posted July 22, 2008 - 07:36 PM

#8

the first one is the one you need.

OR

get the OEM '03 YZ or WR EXHAUST cam


I put an 03 450 exhaust cam on my 98 yz400f it worked so good I can't believe every one doesn't do it.
If anyone gets a 400 or 426 do this first it work perfect.
follow the tips on this web site. now I love my 98 yz400f.:thumbsup: :thumbsup: :thumbsup:

  • wakemaker

Posted July 22, 2008 - 07:38 PM

#9

the first one is the one you need.

OR

get the OEM '03 YZ or WR EXHAUST cam


I went with the yz and again i wasn't diapointed:thumbsup:




 
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