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Valve clearance settings

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SO can valve clearances that are set a bit too tight cause the engine to randomly die at idle?

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Tight valves will generally result in a rough idle and poor throttle response in my experience. The engine wouldn't run good and then randomly quit, it would run poor, stumble and possibly stall all the time.

Tell us a bit more about the behavior and perhaps we could offer more insight.

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I have found that with the XR650L, it is easier to set the valves than to accurately measure the clearance.  I'll probably measure anyway the next time I'm doing a valve adjust, which should be sometime soon.  I want to know if they've changed at all.

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So the reason I asked this question is because I don't work on my bike because I'm not good at it.Im good at riding bikes and playing drums.I have a good friend who is however good at working on them and was in fact the head mechanic at a reputable local shop.When he set the clearances, at first he had trouble finding TDC,then as I watched I noticed that he had trouble with a couple of the settings, almost having to forceably pull the feeler gauge out,hence my thoughts on the too tight settings..since on three rides ..(Just one time during each ride ) the engine died.I've owned the bike since 2008,the bike has never "Just died at idle" ever..hence my conundrum.

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You don't need any serious mechanical skills to set the valves on an XR650L.  Just follow the directions in the service manual.  Buy a feeler gauge set and bend the two that you need for intake and exhaust checking about half an inch from the end.  You only need a few wrenches and a flat blade screwdriver to do it.

I guess you also need the "skill" to take the seat and tank off first so you can get to those little round valve covers.  I think I might just go check mine today, to prove to myself that it's as easy as I'm claiming. :cool:

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Well you are right to question what you saw. Feeler gauges should slide out with slight drag when used properly. Sounds like they may be a bit tight.

I had a buddy who fancied himself a great technician. He would always try to get the clearances as tights as possible but often times they were in fact too tight. You should check them again. 

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On 9/20/2017 at 10:08 AM, Jon K said:

...almost having to forceably pull the feeler gauge out...

That's one of the two trickiest parts of the process.  Knowing how much drag is enough is not easily learned.  Using straight feeler gauges adds to the difficulty. 

The second problem spot for some is keeping it there while locking down the jamb nut.

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So I checked the valve lash again...the motor still has a slight tick....should there be any tick at all??

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I know joe,I bought this bike new in 2007,I hadn't checked the clearances until 5000 miles I've had trouble ever since.Ive never heard it tick like this.The tolerances are set correctly, I'm sure of it.Im wondering if I have some other problem....

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You have to go PAST TDC when you set the right exhaust valve or you end up with excessive clearance on that valve due to the auto decompressor mechanism on the cam. I usually tell people to go 45*/  1/8 turn PAST TDC.  If you are setting them at TDC on the exhaust stroke , they'll ALL clatter from excessive clearance.

Edited by JoeRC51
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Makes total sense Joe,since I believe that is the valve that is making noise.

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I'll assume that you are talking about an XR600. If the idle is too slow, the auto decompressor can engage and kill the engine. 

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Well, I appreciate all the help guys on setting the valve clearances, but the service manual is wrong. I've tried to set these several times and I still have a tick.OFF TO THE DEALERSHIP.

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