R100gs R100R The requirement about rebuild ability make it tough.
The R75GS is the one to look for.
In the high-torque, low rev applications common to off-road, R100GS's had a tendency to run hot and pull the cylinder studs, mine did, but it was later shown that on my bike the aluminum cases were also flawed from poor casting, so it became a warranty repair.
Also the paralever drive shaft failed like clockwork at around 25,000 miles (I was on my third when I sold the bike), turns out the taller suspension ran the two u-joints along the shaft through too wide an angle. IIRC the R75 used the same cases but the smaller cylinders were less likely to pull the studs. Also the driveshaft was just a driveshaft, no u-joints.
"...if the gentlemen of Virginia shall send us a dozen of their sons, we would take great care in their education, instruct them in all we know, and make men of them." Canasatego 1744
