Just a little condensation. . .

[Bun-bun]

When I picked up my '86 K75, I noticed that the gauges were fogged, but since I knew the bike had been sitting I didn't think much of it. Once I had the bike back in my garage, I decided to open the gauge pod and let it air out for a few days while I waited for the new battery to come in. (I was unaware at that time that my battery was being routed to Norfolk Oklahoma instead of Norfolk Virginia, but that's another story. :dunno2:) Having removed the headlight surround and removed the gauge cluster from the bike, I removed the back of the gauge cluster and a good half a glass of rusty water poured out :yow. Every bit of metal, resistor, and circuit board was completely covered in rust and the entire interior was a total loss. I lucked out and was able to Ebay a used cluster for a price that I was willing to pay, and I installed it today. (Still waiting for that battery,BTW) but I took it apart and ran a very light bead of silicon around the inside of the two gauge windows as a precaution against future problems.
The photos show the old and "new" clusters (The "new cluster has 25,125 miles on the odo, the old one has 3,707).

[Bun-bun]

Back of the gauges.

[Chaos]

Save your old unit.  If you are so inclined, it's not too hard to take out the odometer and rotate the numbers to better reflect your actual miles.  Also, those gears sometimes disintegrate, good to have an extra set.  Same with the faceplates, they tend to warp.  And the clock sometimes starts reading chinese.  I've seen cracked windows from people "tapping" the speedo when it sticks  :lol:   Never know what you'll need......

[richarddacat]

Perhaps I need to search this subject but concerning the fogging gauges, is the fix to seal the unit?

Mine does this even days after its been washed.

[pallum]

Saw mine fog up a few times, seemingly randomly, so stole a couple dessicant packs from some backpacks at Walmart and tucked them inside the cluster while putting in LED bulbs, no fog so far!

[WayneDW]

Perhaps I need to search this subject but concerning the fogging gauges, is the fix to seal the unit?

Mine does this even days after its been washed.

I've read that the newer versions of the K75/100 have a piece of Tyvek or similar over the vents in the back.  Tyvek keeps out water but allows ventilation. 
Any remodeler you know will have a roll in his garage or truck that he would be glad to cut a corner off for you.

[Pagman]

All the meter instruments on all the bikes I had/ have fog up. Then again, all my bikes are kept covered in my backyard so they are victims of condensation. Ugh.