Ducati Monster Forum

First time valve adjustment for me.

Decided to install MBP collets which have tightened up my closing shims as expected.

The shims are a tight fit with the new collets (have to tap them pretty hard for them to seat) and they don't spin very freely on the valve stem.

I am at the juncture of swapping/sanding the closing shim on the vertical intake.

I have the belts off so I can feel if the cam is spinning freely.

This is what is confusing; I have two shims that are approx. .001" apart from each other. If I install the thicker one, I can feel cam drag or light binding. If I install the one that is .001" thinner, the cam spins freely. BUT when I check my loaded gap, I come up with .002"-.003" clearance!

My thoughts are that I should be close to .000" clearance, correct?

I really want to get this sorted out before I move on to the other valves as it is a bit of a chore taking closers with the MBP's, on and off repeatedly.

On another note, is TDC really necessary with the belts off? I have watched Chris Kelly's video and he shows the valve adjust with the head off the motor.

Thanks in advance for any insight

The measuring tools don't really measure where the half-rings/MBP collets sit, so if the shims are used, there will be a variance as you've noted.

TDC is necessary so you don't drop a valve into the cylinder when you take the closer shim off.

Rereading my post, my phrasing wasn't definitive.  [laugh]

What I meant was:
If the shims have been run for a while (used), there will be slightly more clearance when installed than with a new shim.
The area where the half-rings sit will wear slowly as the engine runs.

And yes, piston location does not effect the valve clearance measurement.

Thank you for the response and clarification!  [thumbsup]

After an enlightening conversation with Chris Kelley, I grasped the concept that the inner ridge may be of a different "height" between different shims due to the wear you had mentioned.

So, basically, I stopped trying to figure out why the shims I had that were only about a .001" apart would show a difference of .002-.003" of clearance when installed and just sanded the thicker one until the cam spun freely.

I now have a well adjusted vertical cylinder (closers anyway) with .001-.002" gap on each valve.

How much of a change in closers did you make with the MBP's?
I was happy to find no smashed collets at my 34K (13K interval) service, and all well within 'Ducati' specs
(set to DT specs).
I've certainly encountered the head scratching as you have, measuring is all well and good but the proof is in the puddin'.

Averaged about .002"