New camshaft - auto decompression ?

9 replies to this topic
  • jwi

Posted November 09, 2003 - 03:07 AM


I´m changing the cam on my XR 650R, putting in a Hotcams stage 1.
The auto decompression doesn´t fit the new cam so it will be taken out. No problem.
But there is a little springloaded pin in the head which actuates the auto decompression.
Do I have to take this out or do you think I can leave it in there ?
It is assembled with some kind of retainer ring so it doesn´t fall

Thanks for any advice.

  • HotCams

Posted November 10, 2003 - 07:09 AM


Take the pin and spring out.


  • The_Dave

Posted November 10, 2003 - 11:42 AM


What kind of improvment can you expect with this cam?



  • jwi

Posted November 10, 2003 - 12:34 PM


I´ve been writing to Hotcams and here is the answer (thank you Tony for a quick response):

"It depends on where you want your power at. Usually an increase in power in one place is a decrease, or tradeoff to another area. The stage 1 cam gains mostly in the middle at an 11% gain, and a little on the top with about a 4% gain. The stage 2 looses some on the bottom, and has a very healthy increase in the middle with most of the gain on the top, at 14%."

I got the stage 1 cam and if I can get near these figures I will be very happy. I´ve heard a lot of good about Hotcams from others also.
I´m in the middle of installing it right now, will be fun to try it.

  • Old_Man_Time

Posted November 10, 2003 - 09:06 PM


I left the spring loaded pin in. The reason according to the Honda shop that they always took the decompression parts completely out is because of the danger of them coming loose and falling into the motor. The shop mechanic saw no reason to take it out on the XR650 because it was held so securly in place by the retaining clip. So I left it in when I installed the cam. You will note that Hotcams makes no reference whatsoever to the spring and pin. I found that the cam improved my bike performance from the get go. Not in the form of more top end but simply more hard pulling grunt in 1st 2nd and 3rd. You seem to get to the top speeds in each gear just a little bit faster. I didn't notice it as much in forth and fifth because by then your going so fast its hard to tell anything.

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  • mzanden

Posted November 11, 2003 - 10:09 AM


What jetting did you find that works best with this cam?

  • jwi

Posted November 11, 2003 - 10:46 AM


I have just done the breaking in of the cam. The pig started on first kick. I´ll be doing the last adjustments tomorrow, then I´ll take her for a spin to see if the power is there.
I also wants to know if I have to do some rejetting.
Maybe Old_Man_Time can give us some info ?


  • Old_Man_Time

Posted November 11, 2003 - 09:00 PM


I have Honda's power up Kit installed ie. the needle, intake manifold and exhaust tip. I use the 68s slow jet and have used successfully the 170, 172 and 175 main jets. I find that the 170 runs clean in the mountains at elevations from 3000 up to about 6000 feet. I like the 172 the best for all around performance. The 175 definately gives it more all around grunt but doesn't seem to burn as clean.

Also I should add that I have had more trouble jetting my 2002 XR650R than I did my 2000 model with this cam. Still don't know why that is but it looks like I may have to go to the 70 slow jet because it pops on compression with the 2002 bike. I just gave the 2000 in trade for 2002 2 months ago, new off the showroom floor. Im beginning to think I should have stayed with the 2000. Don't get me wrong it runs just as strong but I don't like the popping. I will first mess with the fuel screw to richen it up before I go to the 70 slow jet. In fact I did richen it up with the fuel screw today while I was riding and it did help some. but if I have to turn the fuel screw too much beyond 2 1/2 turns out I will go to the 70 slow jet. I haven't yet checked to see how far out I am on the fuel screw right now. Hope this helps some.

  • jwi

Posted November 12, 2003 - 03:36 AM


I´ve got the power!
Did some riding on gravel roads and the bike feels just great with the new cam. I run 14/43 gearing and now it wheelies on third gear in the same way it did on second earlier (when I could find traction). Don´t think I lost anything down low either, feels the same as before.
Haven´t done any rejetting yet, I have to do some more riding to see if it´s needed.
I also changed the clutch springs to XR´s Only heavy duty, probably a good thing to do.


  • CleanGoggles

Posted November 12, 2003 - 05:05 PM


Congratulations one the cam.
I did mine and it ROCKS.
One of the top five improvements :)

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