XR650r Hotcam, I'm I loosing the auto decomp?

5 replies to this topic
  • rbhman

Posted March 12, 2005 - 09:45 PM


I'd like to install a stage 1 HotCam on my 650r :D . Problem is: I've read that the mod will make me loose the possibility to use the autodecomp. :D By viewing the pictures of the Hotcam, I thought that I could still use the auto decomp by installing the stock gear on the hotcam. On the other hand, I've read threads on this forum that states that the mod will preclude usage of the autodecomp. :p

Could somebody explain how the autodecomp works (or is installed) on the 650r and why would an HotCam preclude the autodecomp from working?

Any hot cam available on the market that would allow autodecomp to work? :)

Thanks for your input :)

  • qadsan

Posted March 12, 2005 - 11:30 PM


Hotcams does not make a cam for the 650r that retains the use of the autodecomp mechanism. I don't believe web cam offers a cam that allows the use of the auto decomp mechanism either. You can however buy the factory HRC cam and all of its associated parts if you want a cam that has the autodecomp mechanism which costs considerably more than the aftermarket cams. Your Honda dealer can get you part numbers, pricing, etc.

  • mountainrider

Posted March 13, 2005 - 03:06 PM


I installed a Hotcams cam in my L.Doing away with the decomp. did not hurt a thing.I think it starts better.Bump the starter and she fires right up. :)

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  • Dave102429

Posted March 13, 2005 - 08:14 PM


XR's Only sells a HRC copy cam for $180 (http://www.xrsonly.c.../camshafts.html) and it retains the auto decomp. I heard the genuine Honda HRC cam is in the $600-700 range. You do loose the auto decomp when installing a Hotcams cam, but you still retain the manual decomp using the decomp lever on the handle bars.

It was explained to me the benefit of the auto decomp is when you try to kick the engine over and if the kick starter tries to kick back (backfire, compression stroke, etc.), the auto decomp engages, preventing the kick starter from kicking back. Without the auto decomp, the kick starter may try to kick you back. But if you know the starting routine, kick through to just past TDC then stomp on it, loosing the auto decomp should be no big deal.

  • qadsan

Posted March 13, 2005 - 08:48 PM


I wonder if their HRC copy cam uses the autodecomp mechanism or not based on the following note on their web page just below the 650r listed cams...

NOTE: All cams, except Honda OEM camshafts, are sold on a core exchange basis. You must send in a useable cam core for the purchase price noted.
NOTE: All of our cams do not use the auto-decompressor.

  • Dave102429

Posted March 14, 2005 - 12:58 PM


When I was at XR's Only, the guy showed me the two cams (Hotcams and HRC Copy) side by side and explained how the HRC Copy cam retains the auto decomp mechanism.

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