XR650L noisy cam decompressor

13 replies to this topic
  • tntmo

Posted April 20, 2004 - 10:41 AM


Anyone ever have a problem with the auto-decompressor on the cam? Mine is making a clicking noise, once every revolution as I turn the engine over with a ratchet, and when it's running it's very annoying. Can I remove the decompressor without any problems?

  • ShaiDanny

Posted April 21, 2004 - 04:47 AM


I can only guess that something happened to the one-way rotation assembly on the camshaft. If this is true, your decompressor, or at least parts of it are turning with the camshaft. This maybe the reason for the clicks.
But then again, if the decompressor is engaged, why would the engine run at all...

As far as I can tell from the 650L's microfiche, the decompressor parts are available for purchase separately (you don't have to buy a new camshaft). This is only a guess - ask your local dealer.
The whole assembly consists of very few small parts.

In regards to removing the decompressor assembly - It could work OK.
I installed a hot-cam in my bike without the decompressor and it starts fine. Of course this may be because of the longer valve lift with this hot cam, so I don't know about the original one.
You could check and see, but don't forget to remove the oil plunger and its spring from the head after removing the decompressor.

  • slip

Posted April 21, 2004 - 12:33 PM



I like your bike. Nice job. :)

  • JetPilot

Posted April 22, 2004 - 05:11 AM


One Way Rotatoin assemby ? What does that mean, that if you turn the camshaft backwords that it will break the decompresser. I ask because I hear the same click sound on my XR600R when I turn the engine :) I did turn the engine backwards while working on it, will that break something on the XR ?
"NO FEAR" If you have no fear, you didnt go as fast as you could have.

  • ShaiDanny

Posted April 24, 2004 - 08:38 AM


First of all, thanks Slip :)
Now, JetPilot, here goes...:
Generally speaking, turning an engine againt its normal direction is not advisory.
Regarding the XR650L, the automatic decompressor encorporates a one-way clutch that is fitted to the camshaft. The decompressor is only engaged while starting the engine (up to about 400-500 RPM) and is released when the engine is running.
As far as I know, the XR600R also has an automatic decompressor on top of the manual one.
Judging from how the decompressor is built, I can't see that rotating it backwards will harm it, but for the sake of your engine, don't turn it backwards.

  • terrordactyl250

Posted March 20, 2010 - 03:35 PM


you ever find out what the problem was? i opened up my engine to find a rattling cam reverse.(sits right next the cam decompresser)

  • ThumpNRed

Posted March 20, 2010 - 04:22 PM


you ever find out what the problem was? i opened up my engine to find a rattling cam reverse.(sits right next the cam decompresser)

Six years...:thumbsup: probably found it by now

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  • terrordactyl250

Posted March 20, 2010 - 05:22 PM


im running out of options. gotta get my bike on the road.

  • dino3310

Posted March 20, 2010 - 10:51 PM


all parts replaceable, just done mine. couldnt afford a new hot cam so i just replaced the couple of parts on the auto decomp. you can remove the auto decomp from the standard cam but you have to weld up the hole on the cam shaft, head trauma's got some photos posted up of it on a thread somewhere in here.

  • terrordactyl250

Posted March 21, 2010 - 06:42 AM


yea im just going to go with a hot cam. i got the money and a can use a little more power. i just hope this stops the ticking. its not real bad but i like my bike to run like new

  • dino3310

Posted March 21, 2010 - 11:36 PM


i forgot to mention i replaced the rocker arm(the one that the decomp is on) it was really worn which might have been caused by the broke decomp, im not sure...
but any ways i cant see any negatives from the stage 1 hotcams, everyone who uses them speak highly of them.. :thumbsup:

  • mitchn06

Posted March 22, 2010 - 04:44 AM


i'm also going to replace the cam on my R, same problem, or so i'm hoping. just gots to wait for the dang thing to get here.

  • terrordactyl250

Posted March 22, 2010 - 07:50 AM


haha yea same here. i wish i can just pick it up and put that bad boy in my bike so i can get back to riding. too bad i snaped one of the bolts on the head while it was comming out...so i got some more work to do before shes back on the road...or better yet the mud

  • jaredc28

Posted March 24, 2010 - 11:44 AM


I had the same problem with the autodecomp ticking on my 93 L. After many many attempts at adjusting the valves, I finally decided to go to a .006 instead of a .004 on the exhaust valve and the ticking went away. bike runs fine, no problems.

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