measuring valve clearance

[998Cruiser]

Originally Posted by TomTom

I Start with the closing shim binding a bit and then sand until it doesnt, so 1 to 3 hundreds of a mm or so, depending on how many times your patience allows to remount and check I wouldnt fall into tears over 5 hundreds either.

Especially with fresh seats I want to keep them zero as the will move up a bit.

Do you rotate the cam to find where the tightest spot is or do you keep it at its TDC position and measure?

Sorry, all these questions, but I'm learning a lot. Great information guys!

[TomTom]

I you go by the bind method you just turn the cam for the whole of the closing lobe and see that it doesnt bind. If you'd prefer say 0.10mm then push a 0.10mm gauge in there and do the same should work.
The cams I have been shimming has been very consistant for the whole lobe.

[chris steedman]

Some cams have a very inconsistant closing ramps. Therefore there is no choice but to go 0.10 closing or obove.

I had a 998s the other month. Usually i go tight but this one was binding on every cam so looser than usual had to do.

Someone mentioned the other day that one of the desmoquattro race cams had unusual closing lobes on purpose to stop valve/collet hammering. This meant you could still set the bike to the loose sloppy closing settings but someware in the cams cycle the slack was taken up. How true is it . I cant comment but it would explaine some unusual findings

[marvin]

OK, here's a question (only semi-related to this thread) for Chris.Tom, or anyone else who knows more than I do.

When you degree cams do you insert a feeler gauge between the opener rocker and the valve to essentially make the gap 0? (measured at 1mm lift of course).

That's the way I've always done it, (just feeling insecure I guess)!

[Old Fart]

Hey look kids,, finally a thread that hasn't been morphed into a Larry V4 rant !

[acruhl]

Originally Posted by chris steedman

Some cams have a very inconsistant closing ramps. Therefore there is no choice but to go 0.10 closing or obove.

I had a 998s the other month. Usually i go tight but this one was binding on every cam so looser than usual had to do.

Someone mentioned the other day that one of the desmoquattro race cams had unusual closing lobes on purpose to stop valve/collet hammering. This meant you could still set the bike to the loose sloppy closing settings but someware in the cams cycle the slack was taken up. How true is it . I cant comment but it would explaine some unusual findings

Interesting idea. I have some corsa cams in the 996, and they are inconsistent to the point where I had to run the closers around .006" to clear one tight spot. And I believe the tight spot was in the transition from the closer to the opener which would support your idea probably.

I just thought the guy making the cams was having a bad day...