[Ducati] Valve Shim Adjustment

Fri Apr 4 00:47:02 EDT 2008

To bring up this thread once again if I might pick peoples brains once more.

To recap:
01 Monster
The smallest feeler guage I have is 0.0015".  The resources I was checking
seemed to think that this was fine.  My mechanic seems to disagree and that
I need a finer guage. We'll get back to that.

All of my opening shims measured with gaps of less than 0.0015" (couldn't
fit the feeler in).  Confirming with my mechanic, he aims for minimal
clearance so this seemed to be expected.

3 of my closing shims measured with gaps out of spec.  To get the delta
between the opening and closing gaps I used 0.0010" for the opening gap and
assumed that it was a safe number that seemed consistent with what my
mechanic claimed that he aimed for when he did my shims last.   With this
delta I calculated the new shims and ordered them.

This catches us up to current events.  The shims are now on my bike.
Stupidly I did not measure the shims first to double check that they are the
size I had expected.  Once they were installed I went back to remeasure the
gaps and make sure they seemed to be right where I wanted them.  When I went
to depress the closing rockers, however, none of them moved.

Which brings us to my fear that I would like to consult with you all on.  If
the rocker doesn't move, that means that the spring isn't closing the valve
at all.  Best case, I managed to get the perfect shim in on all 3 and I'm
golden, but I doubt that since it seems a long shot.  Worst case, the shim
is too large and the valve is impacting the head and stopping before the
closing rocker reaches the end of it's travel.  I have no means to check the
former that I can think of.  If I reach in and spin the shim around the
valve, both the closer (which I changed) and the opener (which I did not
change) spin with the same amount of effort and with the same feel to
them.   I take this as a good sign.  However, the one valve where I did not
change anything at all spins much easier.  While it has been in my bike
since the last adjustment and might be a bit more worn and loose than the
new, this makes me think that the spinning isn't enough to trust that I'm
good.

To check the latter (that the valve head is preventing the rocker from full
travel), I attempted to slip the 0.0015" feeler guage under the opening
rocker to check the clearance.  The feeler guage still does not fit.  Since
I do not know what the original opening gap was exactly, simply that it was
less than 0.0015", I can't be positive that I am not impacting things.

This leads to my questions.
1) My above assumption that checking the opening gap will indicate if I am
hitting the head and preventing full travel of the closing rocker is
correct, yes?  If I saw a greater gap, I would be firmly against the
cylinder head. Otherwise it should read the exact same (which it still may
not be doing in this case, I just want to confirm that the technique is
sound).

2) It strikes me that the only option I really have right now is to pull the
shims off and start sanding them down a bit at a time until I install them
and I get a little bit of play on the closing rocker.  Otherwise I don't
really have any indication that I picked a shim that was too large and am
going to damage things (went from a positive, too large clearance, to a
negative clearance).  To be honest, I am not looking forward to this if it's
the case.  Is there another approach I'm missing?

3) My mechanic recommends finding a thinner set of feeler guages.  Since he
said that SnapOn carried some, I checked there, but didn't see anything that
went smaller than 0.0015".  Did he have a brain fart when I was talking to
him today or are there easily obtainable feeler guages that go down even
thinner?

4) Finally, in checking the clearances after reinstalling, I turned the
engine over multiple times.  I was using the rear tire and fifth gear (I
believe. would need to double check to be sure) to rotate the crank.  I'm
not sure how much mechanical advantage I have turning the crankshaft that
way, but do I have enough that I would be able to deform/damage the rocker,
shim, valve, or head?  And if I did, would not there have been a highly
noticable force needed to turn the wheel?  If I could not have damaged the
engine that way, is that an indication that my shims, while snug, are good
enough?

Thank you for your time and assistance.

Nick Fisher

On 2/19/08, nicholas ivan fisher <blindtreefrog at gmail.com> wrote:
>
> Duh, the head stops the valves upward travel, not the shim.  I was under
> the impression that my valve wasn't fully closing due to the clearance being
> that far aout of line.
>
> And with that straightened out, I think this is all back to making sense
> for me again.
>
> Thank you much for your help, sir.
>
> Nick
>
> -------------------------------------
>
>
> Hi Nick,
>
> Once you know what clearances you have, what shim sizes you have, and what
> clearances you want, you simply calculate the new shim sizes needed to
> correct the clearances to the nominal values.?Put in the new shims and
> recheck?and you should be good to go.? ?All clearances are checked with the
> valve fully shut.? So replacing shims does not change the location of the
> valve stem.? That is why I say the opening clearances are independent of the
> closing clearances.
>
> Hope that helps.
>
> Mike
>
>
> -----Original Message-----
> From: nicholas ivan fisher <blindtreefrog at gmail.com>
> To: ducati at ducati.net
> Sent: Tue, 19 Feb 2008 9:24 am
> Subject: [Ducati] Valve Shim Adjustment
>
>
>
>
> OK, so the only thing that still confuses me, and maybe this will suddenly
> be clear
> once the shims come off, but to fix the closing clearance I would think I
> need a thicker
> closing shim (to push the closer rocker down slightly), but wouldn't that
> also continue
> to push the valve against the opening rocker and not fix the opening
> clearance issue
> at all?
>
>
> Thanks
>
> Nick
>
>
> *******************
>
> Hi N I,
> You are correct with the opener shim calc, but incorrect on the closer
> shim
>
> calc.  The closer shim clearance is independent of the opener shim
> clearance,
> meaning if you change the opener shim clearance with a smaller shim,  it
> wont
> affect the closer shim clearance you have calculated.  So your  closer
> shim
> clearance is .011 and you can calculate the size of closer shim  needed
> from
>
> this measurement, not .011 +.002.
>
> Mike
> www.emsduc.com
>
>
> In a message dated 2/18/2008 8:03:32 P.M. Pacific Standard Time,
> blindtreefrog at gmail.com writes:
>
> Searching the archives doesn't seem to be turning anything up to answer
> my
> current question, so hopefully this question isn't a rehash.
>
> I  cracked open my engine to check the valve shims and adjust as
> nessecary.
> I'm following the write ups and tolerences posted at the  following site
> http://www.westernmassriding.com/index_files/Page9247.htm  and the sites
> it
> links too.  Everything was going fine until I got to  the first valve.
> The
> tolerences I'm aiming for are 0.003" opening and  <0.001" closing.
>
> My unloaded gap measured at <0.0015" (I didn't  have a thinner feeler
> gauge),
> so it's a bit snug
> My loaded gap measured  at 0.012", giving a closing clearance of around
> 0.011which would be grossly  too loose
>
> This procedure seems to be fairly straightforward, so I don't  think I'm
> doing it wrong and I really am that far out of spec, but all of  the write
> ups i've read on the topic seem to assume a slightly more ideal  condition
> then what I'm seeing here.  My assumption right now is that  I need a
> thinner
> opening shim by about .002" to increase that gap, but does  that mean that
> I
> need a thicker closing shim by 0.013" (0.011" +  0.002")?
>
> Am I thinking correctly or do the measurements tell a  completely
> different
> story then what I'm seeing?
>
> Thanks
> N I  Fisher
> *****
>