TDC trouble during 650L valve adjust

7 replies to this topic
  • barchetta

Posted September 22, 2007 - 11:00 AM


I'm having a problem getting to the TDC mark when doing a valve adjustment.

First, about the bike. I picked up a 2000 XR650L with 1500 miles on it. I have removed the smog, Dave's mods (55/158, 2.25 turns out), snorkel removed, Uni filter, 15/49 gearing. The bike runs great, no smoke, starts easy.

Now, about the valve adjustment.
I am using a racket to turn the crank, and as I am approaching TDC, I can feel more resistance. Then as I get near TDC, the crank rotates by itself. So, I can never get it to stop at the T mark. Matter of fact, I have never seen the T mark because I can't hold the crank in place. I have tried this with the spark plug in and out.

Am I being stupid here? Is there a trick to this? Is there too much play in the piston? I am quite surprised that the engine will continue to rotate by itself, especially with the plug out so there is no compression.


  • cleonard

Posted September 22, 2007 - 11:11 AM


With the plug out it shouldn't really do it that much.

I don't even use the TDC mark anymore when doing the valve clearance check. It's not really critical that it is exactly at TDC. The cam justs needs to be away from the lobes, so if you are a little before or a little after TDC on the power stroke then it doesn't matter. If you are one turn of the crank at the end of the exhaust stroke (same as the begingning of the intake stroke) then the lobes will be engaged. This puts force on the crank and may be the reason for the turning that you are seeing.

  • martinfan30

Posted September 22, 2007 - 01:14 PM


+1 on this method. like he said just get the tip of the lobe(of the cam) about 180 degrees away from the follower. then make your adjustment.

  • barchetta

Posted September 22, 2007 - 02:19 PM


Thanks guys I'll do that.

After my mild frustration, I just bolted everything back on and went for a ride. Now, I'll wait until it cools down overnight.

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Posted September 22, 2007 - 04:20 PM


Had the exact same problem trying to get the T mark to line up just this past Wednesday. Asked the motor head down the street how he gets TDC on his Yamaha and he said to just raise the rear wheel and turn the tire slowly with the bike in the gear. Haven't tried this yet on my L but it sounds like it should work. May give it a shot later on when I find some feelers that will actually fit into the lash space and a thin wall plug socket.

  • barchetta

Posted September 22, 2007 - 06:10 PM


On both my XR, and my VStrom, the best spark plug socket is the one provided in the bike's toolkit. On my Strom, it was the ONLY one that would work.

Oh, and I like your idea of raising the rear wheel. Now, I have some options.

  • gnfreak

Posted September 22, 2007 - 06:19 PM


had the same thing going with my 600r. finally got it after many failed attempts. kinda drives ya crazy! next time i'm checking valves i'm going to use the wheel method. thanks for the tip

  • XR650L_Dave

Posted September 24, 2007 - 08:12 AM


If you use a breaker bar instead of a ratchet, you can ease it to TDC, you hold it there for a sec and then it won't move on its own.


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