I did a fly and ride recently and picked up a 1992 K75s.
http://www.motobrick.com/index.php/topic,7539.0.html While looking for parts on Craigslist a couple days ago, I chanced upon a complete 1990 K75s, same color, for an attractive price. So... now I have two bikes, which I am going to merge into one.
The 1992:
40,000 miles, runs very well, but is a bit rough cosmetically, including a lot of corrosion. I rode it over 700 miles and have noted a few minor flaws that can be fixed. And it's got some deferred maintenance, oil leak, dead shock, crappy 10-year old tires, etc.
The 1990:
180,000 miles, but nobody told the engine it's supposed to wear out, it runs about the same as the one with 40,000 on it. However the 2nd gear is skipping in a way that makes we wonder if the whole tranny is going to lock up. The bike was a commuter, well cared for, and garaged - so it's not corroded. But I think she's about at the end of her useful life; the previous owner was concerned about a few other mechanical things too and decided it was not worth trying to keep it going.
The plan:
Dissemble the 1990. Address the deferred maintenance, including spline lube and oil leak, on the 92, reassemble with the "best of both bikes" parts.
So far the intended transfers from 90 to 92 are:
Tires (new Conti-Gos) - and maybe the wheels too. I think I like the look of the older wheels better, and the paint on the 92's wheels is quite bad.
Fork tubes - the 92s are badly pitted
Gas Tank - the 92 has a difficult dent on RH side and had been sitting a while, the 90 has only a small dent and never got a rest - so I think the internals are probably better.
Corbin Seat - but needs recovering
Complete exhaust - 92's is corroded
Square mirrors - again, I think the older style is more attractive than the lollipops on the 92.
All manner of small covers, brackets, fasteners - basically, whatever is nicer will get moved over.
I suspect I will have a bunch of questions along the way, and I will report in whenever I make some significant progress. Please feel free to make suggestions along the way.
First question - is there any reason I should not use the older style wheels on the 1992 bike?
Some pics: