How to get tdc

5 replies to this topic
  • 3ECRFX

Posted December 04, 2007 - 04:57 PM


My dad rides a 2001 xr650r. I was going to check the valves and was wondering how to get top dead center, so all valves are closed. I have done it on my 250x but the 650 seems different.

  • jclaus98

Posted December 04, 2007 - 05:04 PM


Its the same as every other Honda before and after it; remove the two plugs in the left side crankcase cover, one will be large, the other small, one will have a bolt inside and the other will be a sight hole. Rotate the bolt in a clockwise direction while looking in the sight hole until you see a small mark with a "T" marked next to it, that is TDC. Good luck.

  • 3ECRFX

Posted December 04, 2007 - 05:09 PM


Thank you for the quick reply I figured it had to be pretty simple!!

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  • creeky

Posted December 04, 2007 - 07:00 PM


Make sure that the piston is coming up on the compression stroke when you line up the "T" mark. Don't confuse the "F" mark with the "T" mark.

  • dmvmechanics

Posted December 15, 2007 - 10:44 PM


just kick it over slowly w/out pulling the decomp lever. when it gets hard to move, you should be at tdc

  • HawkGT

Posted December 15, 2007 - 11:41 PM


And there's only one cap on the left case cover of the XR650R--the sight hole cap. Some people remove the whole cover to access the flywheel nut for turning the crank (that's what the service manual says to do). I just remove the sight hole cap and peer through it with a small mirror while I turn the engine over with the kickstarter. It's easier to turn the crank over if the spark plug is out (although I usually don't take it out).

One way to know if your at the compression TDC instead of the exhaust TDC is to feel for slight play in all the rockers. Only on the comp TDC will all for have some play (assuming none of the valves have gone to zero clearance).

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