XR650L Hot Cams - advance cam timing?

10 replies to this topic
  • CheGuevara

Posted July 05, 2005 - 09:03 AM


A quick run-down of the motor being built; 675cc, 10.25:1 wiseco, mild porting by Jay Wright of BareBones Machine, and installing the Hot Cams Stg1 cam.

When Jay sent my head back (this was a while ago - I'm moving pretty slowly on this project) he suggested that I advance the cam timing 4 degrees from standard. To quote him exactly: "Advance the cam a bit... 4deg or so from the std settings... This will make it a far nicer street-bike... You’ll feel the effective bump in compression immediately... If it pings, it shouldn’t, retard it some..."

Now I trust that Jay knows what he's talking about, but at the time the cam I would be using was undecided. I'm curious if anyone else with a similar set-up has tried this on the L, or bothered to slot the sprocket at all? What were the results?

I've fired off an email to Hot Cams to see if they have any advice, but figured I'd cover my bases and ask here as well (I also searched the forum but came up with nothing).


  • Rover31

Posted July 05, 2005 - 06:48 PM


I am having the same moter set up getting done right now also. My ? to you or anyone is this... with this higher comp. piston and the hot cam not alowing the decompressor how is starting? is it going to kill my starter?

Also White Bros. is not listing a cam now are they avail?
I may have to go with the HRC I guess?

  • XRL_Rider

Posted July 05, 2005 - 07:50 PM


I am running a J&E 10.5/1 piston and the stage 1 Hot Cam with a pumper carb. The E-start handles the combo fine. I dont know how well things would work with the stock carb though.

  • Rover31

Posted July 05, 2005 - 09:32 PM


I actually have been running a pumper for the last year also... Ain't they great!

  • Rover31

Posted July 05, 2005 - 09:35 PM


Hey I didn't mean to highjack your thread. I do know that if you study the cams & their timing/duration you will notice that the roadrace cams have a longer opening, this creates more time for the intake valve to be open = more top end.
I have just been looking at all of these recently. Look at megacycle cams they provide a lot of info on that stuff.

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  • frankstr

Posted July 06, 2005 - 05:17 AM


I would not advance the cam that much unless i had actual dyno time doing so. Dial the cam in according to spec......IMO
Advancing a cam improves the bottom end power and retarding cam timing helps top end power..
Unless you have time to play on a dyno with cam timing and different cam grinds, Install the cam according to the cam card specs..... :)

  • CheGuevara

Posted July 06, 2005 - 11:15 AM


I did get a reply back from Hot Cams (and a very quick reply at that) -basically stating that the lobe centres for their cams had been altered from stock to present what they felt was the best possible curve. As a point of interest I asked if the lobe-centre specs were readily available (they are not on the website or the card for this cam), but it seems they have been long-ago misplaced or forgotten for this particular cam.

Kudos to the folks at Hot Cams (Sean Johnson in this case) for being quick to reply and as helpful as possible.

  • XR650L_Dave

Posted July 06, 2005 - 01:59 PM


Dial-guage, Vblocks, degree-wheel.
That's all you need to check.
They just don't want to tell!

  • CheGuevara

Posted July 07, 2005 - 12:06 PM


LOL - I'm not so sure they don't want to tell as they list it for every other cam.

  • anttismo

Posted July 09, 2005 - 12:02 AM


.....Kudos to the folks at Hot Cams (Sean Johnson in this case) for being quick to reply and as helpful as possible.

I don't have anything specifically to say about your topic, but I agree whole heartedly with this. I also asked a question recently for my particular concern, and the reply was quick and helpfull :)

  • The Bossman

Posted July 09, 2005 - 06:01 AM


So these guys make a camshaft that they don't even have the specs for?
I would like to see ANY self respecting company in the HOT ROD world try that.
So you wouldn't mind if JE had no idea what their pistons compression should be or what thickness the rings are?
Each camshaft should come with ALL the information that is needed for a proper installation.

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