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I ruined one of my half-rings, when removing it my tool slipped off the closer rocker arm and the ring got pinched between the closer shim and the valve stem. It scored the half-ring badly (it was a B#TCH to get out as I had no leverage) and now the closer shim (seems to) catch when it slides up over the rings and won't spin freely on the valve stem. I picked up a replacement set of half-rings, but I've read that new half-rings will add a thou or so to the thickness of the closer, at least until they break in. I ordered the closer shim to fit tight, and am thinking I might need to sand it down. What's the best way to do this? I've done it previously by putting some 400-grit wet/dry paper on top of a sheet of glass. It took a long long time to shave off a tiny amount, just wondering if anybody's got a better way to do this, maybe valve lapping compound?

Any replies greatly appreciated.
 

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I use and inspection grade granite slab but in a pinch on a piece of glass use some 220 wet dry sand paper (wet) and I do about 8 figure eights and clean and measure. Pressure makes a difference and you do not want to go past what you are shooting for so do a little at a time.
 

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I have not done this on Ducatis, but have used a knife sharpening whetstone with oil to hone down shims.
Cheers
 

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I have not done this on Ducatis, but have used a knife sharpening whetstone with oil to hone down shims.
Cheers
Way to go, just make sure the stone is flat, and not warn from use.
 

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I ruined one of my half-rings, when removing it my tool slipped off the closer rocker arm and the ring got pinched between the closer shim and the valve stem. It scored the half-ring badly (it was a B#TCH to get out as I had no leverage) and now the closer shim (seems to) catch when it slides up over the rings and won't spin freely on the valve stem. I picked up a replacement set of half-rings, but I've read that new half-rings will add a thou or so to the thickness of the closer, at least until they break in. I ordered the closer shim to fit tight, and am thinking I might need to sand it down. What's the best way to do this? I've done it previously by putting some 400-grit wet/dry paper on top of a sheet of glass. It took a long long time to shave off a tiny amount, just wondering if anybody's got a better way to do this, maybe valve lapping compound?

Any replies greatly appreciated.
I find the emory cloth type of sand paper seems to last longer, but any type of sand paper will work. 200- 400 grit is nice as it wont take you forever to remove material. I follow it up with 1000 grit just to get a nice mirror surface. Just make sure you have a flat surface to sand on. A piece of glass works. I have some granite inspection plates that I have used. Technically, you are supposed to make a figure eight pattern. I find it difficult to do that while pressing down. I do a circular motion, maybe 3 full revolutions, then turn the shim 90 degrees and do it again, and turn, then again, etc. It takes maybe a minute to lap down .001 in. depending on how hard your are pressing down.

Years ago, I bought a lapping machine, no more hand lapping for me!
 

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Discussion Starter #6
Years ago, I bought a lapping machine, no more hand lapping for me!
I had this vision of making a jig which would hold a shim perpendicular to the face of my disk sander and allow me to spin the shim as it contacts the disk. My lathe is all in pieces or I'd use it to machine it down. Given my level of skill on the lathe, sandpaper is probably safer...
 
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