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Discussion Starter #1
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)

------ 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.

:headscrat :headscrat :headscrat
 

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the "hanging throttle" is an issue that plagues MANY BRP's. First, make sure there's an appropriate amount of slack at BOTH ends of the throttle cables. Also double check the routing to ensure there's no binding (I mess that up almost every time I pull the carb out) Also, double check your valve lash. I'm uncertain as to how the bike would run if the valves were floating at idle, but I've been told that can cause the problem. Aditionally, (not that you're dumb, but I have to put this in) check that your idle set screw is functioning properly. Then set it accordingly. There are quite a few good resources for this bike online. Look around and see if anyone esle has had the same problem, and see if they have a good solution.
 

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Discussion Starter #3
hummm.....thanks for the post.

o.k.

Let's assume the idle thing isn't happening. (I know the valve clearance is right, the idle set screw on my Edelbrock is set right - I also can check the idle RPM via. my Vaypor computer, and I have had the throttle cable thing happen --- but doesn't happen nearly as much with the motion pro cables supplied with the Edelbrock)

I guess.... my main question is --- with the cam sprocket alignment....

What are the effects of having your cam chain timing off? Will it run like absolute crap?

Has anyone else installed a Hot Cams Stage 1? Did you have the same cam sprocket alignment, or was it dead flush with the cylinder head?
 

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Discussion Starter #6
Chain never changed --- 1,500 miles on bike..... head cover never taken off....

Not sure about retard or advancement on the Hot Cams Stage 1 ---- this may be the answer to my question.....maybe the hotcams is set to have a slightly differernt timing....(if it is....question answered --- DONE!)



The cam lobes are straight down.... the flywheel is on the T mark for Top Dead Center of the compression stroke ---- but, the cam sprocket alignment is slighly higher on the exhaust side. (not perfectly aligned with the cylinder head)

funny thing.... the service manual has one pic showing the sprocket that looks like mine (with the exhaust timing mark slightly higher), and another photo that shows the timing marks perfectly aligned with the cylinder head....
 

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Not sure about this particular application but on a few of the engines I've done you had to play with the cam timing. You run up to 3 deg of advance or retard, depending on the engine and where you want the power to move to. You advance to move the power to a higher range (cam designed for 2,500-4,500 rpm, adv 1 deg and it works better 3,000-5,000). If you wnt it to align you have to use a stepped key(on the shaft) or other technique to change the relation between the lobe and the gear....
 

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Discussion Starter #8
After reading about retarding or advancing the cam timing.... I'm starting to think that Hot Cams has purposfully changed it a little to compliment the cam. I could also just simply keep riding it and see if I get any overheating of the headers... I do know.... the different is in the 3 Degree range --- even though I haven't specifically measured the difference.

To bad....the Hot Cams instructions are horrible. They simply ship with a small data card. (if I looked closer of which probably says they have slightly different timing)



Thanks goodness for the Forums! :thumbup:
 

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even so you can do as i did.take the camshaft sprocket to a machine shop so you can adjust your cam..its easy and cheap..but in your case (hotcam) i would get more information with someone who haves more experience with that kind of situation...
 

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Discussion Starter #10
with it being the weekend ---- couldn't call HOT CAMS. I plan to call tech support first thing tomorrow morning....

I'll post up what I come across....
 

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Try the thumpertalk.com (XR650 forum). I have seen similar threads on that site, most people have great information.
 

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Discussion Starter #12
Although.....went riding today again....

did I mention the XR will now do 3rd gear wheelies without the clutch? ----and with semi-highway gearing! 15-48...

The timing can't be that far off.....and if it is....it's for the good.
 

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if your timing mark on the exhaust side is high and the mark on the inlet side is a little low it indicates a worn cam chain ............. actually normall for an XR6 , i probably would have replaced the chain while you were in there ........... too late now i guess. One tooth out and they start and run like crap.
 

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Discussion Starter #14
I took the cylinder head cover off again....(the cam sprocket and chain look brand new...although I wouldn't be surprised if it has streatchd a little)

This time --- with ONLY the timing in mind.

I found out something interesting..... with the flywheel on TDC, and the CAM CHAIN TENSIONER out.... the cam chain sprocket/chain has a little bit of movement at the countershaft before it engages. (just enough to have me question it) With the cam chain tensioner in.... it is solid as a rock.

This is what had me questioning it....

Also --- the idle isssue --- I figured out to be a LEAN condition of the Edelbrock carburator. I dropped in a richer needle this morning....

It is RUNNING PERFECT!

:D :thumbup:

This mod has been worth its weight in GOLD!
 

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Discussion Starter #16
The power difference has been huge!!!! It is like what it was like after un-corking the pig for the first time.

I read that the Hot Cams STAGE 1...DOES NOT hurt low end grunt. I can confirm this --- I would even say that it has MORE low end, with a very, very meaty middle. (its the stage 2 to stay away from if you have a stock engine...most guys running the stage 2 also compliment with a 680 kit to make up for the loss in low-end)

The bike itself now has a different low-end growl. It just sounds MEAN.

I've also noticed.... the bike can handle more aggressive Edelbrock accelerator pump settings as well..... which = wheelies....weeeeee!
 
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