Hey all.  I am blessed that the original owner kept all his paper work for the sale on my 87 K100 LT.  The dealership installed the accessory gauges at the time the bike was bought.

Couple of questions.  The temp gauge reads accurately, enough to let me know that I have a stuck cooling fan and was able to get things cooled down one day before a boil over.  Bad news is that it has moisture in it.  It fogs over as it gets warm after an hour or so of riding.  Anyone tear into one of these?  Can you dry and re-seal it?

Gas Gauge, works pretty good.  The low level corresponds nearly exactly when the low light illuminates on the instrument cluster.  High (full) level never reads full even when I fill fuel to the point it will flow over. It gets close, but always at least one line away from "1".  Can this be adjusted?  (I am too used to cars where you fill the tank and it reads over full on the gauge)

Thanks in advance!!

Step by step photo teardown of a temp gauge.

Sorry can't answer question #2. The OEM schematics for the auxilary gauges doesn't show any adjuster.

It's a bit difficult to explain this and I don't have a gauge I'm going to strip just to take pics, but here goes:

The gauge in Rob's link has had the bezel removed by simply levering the edges up bit-by-bit. I have a screwdriver that I ground down to a thin blade which I insert under the edge of the bezel (with difficulty!), then gently push it round the gauge so that it lifts the edge of the bezel in one go. They never come off neatly, but my method is a lot neater than just levering the edge up.

To get the best seal when reassembling, loosely assemble everything then put it face down on a folded towel or similar. Push down as hard as you can to compress everything together, then fold the bezel back over in four places at ninety degrees using a flat-blade screwdriver as the tool: go zero degrees, one-eighty degrees, ninety degrees and two-seventy degrees. Keep the downward pressure on at all times. Now work round the rest of the bezel with the flat-blade screwdriver, squashing the bezel flat each time. You should end up with something that looks like a flat pleated curtain rather than the not-quite-flat ripple in that picture. Use some sealant if you feel it's necessary but I've never bothered.

I haven't had a speedo or tacho mist up again when stripped and reassembled like this but YMMV.