winkle caps- how to?

[MotoMike]

I posted these questions in my 450 lives post, but it might be burried. So hope the redundancy is ok.

In checking the valve lash I found .003" on the intake and .0025" on the exhaust. I am uneasy about the exhaust even though it is within specs. Will have to borrow a mic and order some winkle caps. If I understand correctly there should be no conversion. That is to say If I want .004 on the exhaust I need a cap .0015 thinner than the one I have. is that correct?

In mic'ing out the caps, is the underside flat so that the mic will fit cleanly? the measurement is from the flat inner surface to the top, and not skirt bottom to the top?

Also. Is there a method to get the caps off without a high zoot ducati single valve spring compression tool?

Thanks in advance, I wait with bated breath

Mike

[ccambern]

I was able to compress my springs enough with an (ahem) screw driver between the spring and the rocker. I was very careful not to nick anything, or pry on any polished surface, and all turned out OK. My exhaust valve was pretty tight after initial break-in, so I went ahead and ground down the cap a bit, rather than wait for a new one.

[Bevel bob]

It is possible to lever the valve down but damage to the alloy cam tunnel is easily done if you lever against it, A mike usually fits into the cap, I would not bother getting a new cap , just pick up an old chippies oil stone and rub it down in a couple of minuits ,use oil and rotate the cap to even out the cut,check that the cap is true by rotating and checking with the mike,if out correct it by a little offset rubbing. I doubt you will get the cap size you want otherwise.Clean off carborundem dust and wash the cap and your hands ,dont get it in the engine!!.

[DewCatTea-Bob]

" That is to say If I want .004 on the exhaust I need a cap .0015 thinner than the one I have. is that correct? "

____ Yes but, if you get a used cap that someone has tried to grind-down a good bit, then don't expect the math to work-out as figured ! ... Cuz then once the expected to be correct shim has been installed, ya can then end-up with a new clearance that's a couple-thou tighter or looser than it was prefigured to be. _ And really bad ones will not have a consistent clearance-measurement as the shim-cap is rotated on the valve-stem.


" In mic'ing out the caps, is the underside flat so that the mic will fit cleanly? the measurement is from the flat inner surface to the top, "

____ Of course, that's all correct !


" and not skirt bottom to the top? "

____ The skirts vary in length & thickness/width, so ignore such skirt differences, as they don't come into play anyway.


" Is there a method to get the caps off without a high zoot ducati single valve spring compression tool? "

____ But of course... I recommend using a large/long screw-driver, which has a SQUARE (as opposed to round), shaft.
Ya then place it's flat-blade tip-end (with it's flat-tip wrapped with a few layers of duct-tape), all the way back & under the head's internal alloy-lip/ledge (that's directly beneath the rocker-arm), and press the handle's square-shaft down against the spring-tie so as to lever-down the springs & valve, to make just enough space to remove/replace your shim-caps.
__ A square-shafted screw-driver -(of the type which does NOT have the sides of it's square 45-degrees out of alignment with the flat of it's blade), is needed so that the spring-tie will thusly more likely stay level and thus-then press-down both springs rather equally.
It really shouldn't matter which side of the spring-tie that the flat-side of square-shaft presses-down against, but if the spring-tie doesn't stay fairly level (and thus presses one spring downward considerably more-so than the other), then, perhaps trying on the opposite-side of the spring-tie, may THEN quite possibly work better for ya to keep both springs compressed rather equally. - (Although not actually a real big concern to keep both springs perfectly levelly-compressed, in any-case.)
Also, sometimes the spring-tie & springs will get levered-down okay but without taking the valve & keepers downward along-with as well...
So when that RARE-event occurs, you'll then need an extra (smaller) screw-driver or other thin-tipped wedging-tool to wedge between the shim-cap & the rocker-tappet, so as to then-next get the stuck-shut valve to budge down & out of it's closed position far enough to get the shim-cap out from between.

____ Below I've added a pic showing the possible damage-results of using an improper lever-tool too close to the sharp/thinned edge of the lip-ledge, thus then allowing the tip-end of the (unrecommended) lever-tool -(that's then under pressure from the valve-springs), to chip-off pieces of the tapered/thin-edge of the lip-ledge -(underneath of which, the tip-end of the recommended screw-driver is to be well placed).
Now ya can see why I suggest that ya put a few layers of duct-tape over the blade of the screw-driver's tip-end, and also be sure to get & keep it back in underneath far enough, (away from the sharp/thin edge of the lip-ledge), whilst levering-down on the handle-end.
__ I-myself have never had any such chip-damage (as seen in the pic) happen to occur, even when using a rather ordinary screw-driver without any duct-tape. _ So I'm now thinking that that kind of excessive chipping may have been caused by fitting the blade of a screwdriver up-into the narrow slot between the lip-ledge & the bottom-side of the rocker-arm pivot, which I suppose could then lead to enough pressure to bust-off such large chips from the thin-edge of the lip-ledge (as the screwdriver is further levered downward in attempt to compress the springs far enough). _ (Not that this kind of damage is critically important to avoid but, it's a sure sign of poor or non-caring mechanical-work done by some nonDUKE-mechanic !)
So just in case, I'd suggest avoiding the use of that rather narrow slot to place the tip of your screwdriver into.


Fun-Cheers,
DCT-Bob

[MotoMike]

thanks much for the advice. Bob do I sense that you don't like to reduce the caps on a stone? Maybe i can talk you into sending me a selection of caps, that I can try til I get the right one and send back the ones I don't use? You know for a nominal fee.

[DewCatTea-Bob]

" Bob do I sense that you don't like to reduce the caps on a stone? "

____ You "sense" correctly but, I'm actually okay with using a good/flat stone for taking-off amounts less than .0025" .


" Maybe i can talk you into sending me a selection of caps, "

____ I really don't think your particular need is great enough to bother with doing that.


Dukaddy-DUKEs,
-Bob

[MotoMike]

" Bob do I sense that you don't like to reduce the caps on a stone? "

____ You "sense" correctly but, I'm actually okay with using a good/flat stone for taking-off amounts less than .0025" .


" Maybe i can talk you into sending me a selection of caps, "

____ I really don't think your particular need is great enough to bother with doing that.


Dukaddy-DUKEs,
-Bob

Bob

I appreciate your patience in dealing with me, I know I am somewhat a nerd. And You can't blame a guy for tryin

Are you saying that at .0025 (or only 5/10,000ths of an inch more than the minimum) on the exhaust is not a problem, or are you saying that since I have only .0015 to take off to get to an accepable lash, it is ok to stone it?

hat in hand regard,
Mike

[ccambern]

You could measure it hot and see where the clearance is. If the valve isn't hanging open, you could leave it alone for the rest of the season...

[DewCatTea-Bob]

" Are you saying that at .0025 (or only 5/10,000ths of an inch more than the minimum) on the exhaust is not a problem, or are you saying that since I have only .0015 to take off to get to an accepable lash, it is ok to stone it? "

____ My reply to that is: 'Either, Or' .
__ I'd also prefer the ex.clearance to be greater than just .0025, but I'm not sure that the desired increase is worth the trouble of messing with it.
If you really wish to carefully stone-down a thou or so, then you might as well go-ahead while it's still easy to get at.


Dukaddy-DUKEs,
-Bob

[DewCatTea-Bob]

" ALWAYS work in a figure 8 motion.
A figure 8 will even out the pressure on the item. "

____ That's very good advice Graham ! _ Although I'd add that it should also help to rotate the cap 90-degrees, during half of the total number of figure-8 laps being done. - (Such as for instance first doing 25-laps followed by 25 rotated-laps (over & over), working-downward, to lap-sets of 15+15, and then finally 5-laps + 5 rotated-laps,, as the intended-goal is approached.)
Still, I wouldn't advise going-for more than .005" of total reduction.
__ Doing circles instead (of 8s), would tend to wear-down the outer-edging more so than the center (of the shim-cap's top-surface) !
____ In the event that a shim-cap has gotten too thinned-down (or was already a slight-bit too thin for it's intended valve), then ya could add a 'dot' of aluminum-foil to the inside of the shim-cap...
__ To make such a shim-spacer dot, place a sheet of (unwrinkled) foil over a flat piece of inner-tube like rubber, or flat-cork, (that's laid-flat on a hard/flat-surface!), then set a shim-cap (placed bottom downward) on top of the foil, then place a hard piece of wood on the top-side of the cap, and then give the wood a good/hard whack with a hammer.
The shim-cap should then cut-out it's own perfect-fitting shim-dot, for proper placement within the shim-cap. _ If your first tries at pounding-out foil-dots don't fully cut/punch-out the foil-dots from your piece of foil-stock, then take the piece of foil-stock and align your pre-intended dot over the bottom-side of your shim-cap and use a spare valve's stem-tip to finish fully pressing-out your intended foil-dot from the foil-stock & into your intended shim-cap.
__ Re-mike your shim-cap to check it's new thickness, and perhaps add more such shim-dots until you've made-up up to no more than about .0025" of additional thickness. _ As otherwise, you could expect to loose up to 20% of your added thickness during engine-use, cuz using too many foil-dots will end-up getting their combined-thickness compressed, (due to the vastly repeated-pressures of the rocker-arm pressing against the valve-springs).
So I really wouldn't recommend fitting more than 3 or 4 layers of such aluminum-foil shim-dots, within any shim-cap. _ (Although taller shim-caps which have the longer skirts -[over 2.5mm deep], could probably accept more of such layers.) _ As too many layers (of such foil) will compress too much to remain at the setting which you've adjusted.
__ This fitting of such shim-dots was once a common-practice, so whenever ya come-across used shim-caps, be sure to check & see if they may already have any shim-dots within them. _ Ya can easily see the difference between a normal/bare shim-cap & one which has a shim-dot within, as any modified shim-caps which have the foil-dots within, also have a brighter/shinier ceiling within !
If one is not aware of this difference, they may think that such a modified shim-cap is just as normal,, cuz after the foil-dots have been used within for a long time, they then really look as if a natural part of the inside of a shim-cap !
To remove such foil shim-dots, you'll likely need a pointed-punch to dig them out. _ (Which ya may or may-not wish to choose to do.)
__ If your DUKE -(not a mere 'bike' ya know!), is found to have any shim-caps with shim-dots within, then ya know that at least at one time, it was in the hands of somebody who 'Cared' about babying (at least) their engines. _ (Like MotoMike seems to be.)


Hopeful-Cheers,
-Bob