question on Valve specs for those who have worked on them

3 replies to this topic
  • jlm400

Posted October 03, 2000 - 05:19 PM


Ok, I pulled off all the junk and got out the feeler guage. On the Intake valves the specs in MM are .15 to .2 I was able to get a .127 in quite easily and a .152 was good and snug. Since we can only get shims in every .05 mm should I shim up my intake valves or not. I guess it depends on which measurment you take the .127 or the .152. So that asks another question how snug should it be when you take the measurment.

Also when you measure the clearance it is very difficult to slide the feeler guage into the gap at a straight angle. You end up coming down at a sharpe angle and in my case the feeler guage seems to bind up a little until you get it under the cam lob. Then it seems to free up a little. This makes me think that one size larger feeler guage would fit if you could slide it in at a straight angle. Did anyone else experiance this or am I just getting way to particular.

sorry about the long e-mail and thanks for the help.

Also just an FYI my exhaust vales were both measured at .203 snug and .229 tight on a spec of .25 to .3. Both of these will get a one size .05 larger shim.

It has been an entire year of riding on these measurments.

  • Hick

Posted October 04, 2000 - 06:00 AM


I use a feeler gauge with angled ends and had the same problem. Increasing the bend at the end in a slight curve helped some, but they still bind when you stick them in there. I don’t think the binding alone would prevent you getting a size wider under there. If you can feel some resistance with the .152 then I would say that is your measurement.

My exhaust valves also tightened up a bit quicker than intake but that makes sense to me.

I didn’t have to face quite the dilemma you are, it sounds like your intake clearance is pretty close. If forced to choose I would opt for a bit loose over a bit tight. On the other hand your clearance does fall within spec in the strict sense so I wouldn’t worry about riding it like that either. I’m no help at all am I?

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  • jlm400

Posted October 04, 2000 - 06:32 AM


Another question. The reason I pulled my bike apart is that my valves were making a LOT of noise the other day in an Enduro. Does anyone thing that the .203 clearance I have on my exhaust vlaves on a spec of .25-.3 would make my valves make that much noise or am I tracking the wrong problem. That just doesnt seem to be out of spec enough to make that much noise to me. Maybe I am wrong.

  • Hick

Posted October 04, 2000 - 11:06 AM


I would think that looser would be louder. I know that in tappet style car engines too much lash results in an audible ticking sound while too little creates premature wear and bad performance but no extra noise.

My 426 was making noise that I originally assumed was valvetrain (it sure sounded like it) but turned out to be coming from somewhere else. Fire it up and stick your ear down there and see if you can’t determine the area of the motor responsible for the noise. Someone (Matt Porritt?) here suggested holding one end of a piece of steel pipe against your ear and the other against the motor as sort of a moto-stethoscope to detect the source and maybe cause of engine noise. I haven’t tried this but it sounds like a good idea.

If I were convinced the noise emanated from the head I would check the chain tensioner and the cam chain tension. The manual also describes the wear limits of the cam chain. I doubt this would have happened but maybe the tightening valves have resulted in an overly taxed (loose and stretched) cam chain.

I hope its nothing serious.


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