XR650R hot cams stg 1 installation question...

4 replies to this topic
  • arctic954

Posted November 05, 2006 - 05:34 AM


I just installed (2 days ago) an XR650R Hot Cams stage 1 camshaft....

Have broken in the camshaft and everything is running well ---

But --- am starting to 2nd guess something.

When I had the cylinder head cover off --- looking at the valves & cam .... and with the flywheel mark on the T denoting Top Dead Center of the piston on the compression stroke....

The timing markings on the cam sproket were not perfectly in-line with the cylinder head. The EX marking on the sproket was a little higher than the left marking (the timing marks were not perfectly in-line with the cylinder head)..... but, when installing the HOT CAMS, I made sure that both lobes were pointing down.... (both valves to be closed at TDC) and I also made sure that the sproket and chain were immediately zip-tied to the frame as to make sure nothing slipped a tooth. (in other words, if the chain slipped a tooth...it was slipped before I installed the new cam)

------ is it possible I'm off a little bit on my timing? (maybe the bottom sprocket slipped a tooth? I also made sure to align the sproket flange mark to the hot cams alignment dot...)

------ does the engine run like crap if the cam sproket is off by a single tooth or two?

------ is this normal when installing a Hot Cams?

The reason I am second guessing this....is because the XR at intersections would not want to idle down to the standard 1200 RPM at times....(it would sometimes like to stay around 2000-2300 rpm even while warmed up) Not sure if this is a valve timing issue, or maybe an intake vaccuum issue.

  • overrev

Posted November 10, 2006 - 07:06 AM


your timing isnt a cam issue. you are using the same crank, chain and cam sprocket as you started with, so it will line up the same. (you have to turn the cam to match the bolt holes, correct?)
If its off a tooth you will likely know. sounds more like a jetting/ air leak issue.
a tooth off in either direction will make the marks noticeably high/ low. chain stretch will affect alignment a little

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  • rdahl

Posted November 10, 2006 - 07:43 AM


don't worry...i just installed my stage 1 Hot cam a few weeks back and encountered the same issue. Even took the chain off and tried the next tooth but that was way off. BUT THEN when installed the chain tensioner Wa La the marks lined up. I think the slack in the chain is what throws off the marks, once the chain is tight everything was good. I have noticed a slight variation in idle....but i know that just goes hand and hand with more agressive cams.

  • zackary

Posted September 01, 2007 - 07:14 AM


Are there any tricks to the Cam install on the 650R? Anything I need to know to install the stage 2 and remove the decompression device? Hot Cams instructions are very basic. Also wondering about all the cautiions about carbon on the head- I'm sure not going to pull the head and scrape pistons and head, to install a cam ;-)

thanks, ed ed8300@yahoo.com

  • Old_Man_Time

Posted September 01, 2007 - 07:12 PM


This is normal when installing the Hotcam. As long as you were close as you could get in lining things up it is right. You already said when you tried to change it a tooth off in either direction it was way out of alignment. This means you were spot on with your final installation.

You should be able to set the idle so low you can almost count the crank turning by ear (slight exaggeration) . The hanging idle can be caused by several things:

1. I assume you already had the power up kit installed (68s idle jet, changed to the power up needle on 3rd clip, and 168 to 175 main). If the power up kit is installed and you correctly adjusted the valves (The valves must be correct if they are not clacking and it runs good when you open it up).

2. Then move on to the next possible hanging idle cause. You have the idle set too high. If you do it will always hang for a few seconds after quickly throttling down.

3. The throttle cables may be routed incorrectly (make sure the cables are routed above the tank mount not below) and it is hanging up and not snapping shut completely. Lube the cable. Could have a pinched cable but check to make sure the throttle cables are properly installed into the throttle grip and that there is not too much slack.

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