Here's a list of things, in no particular order of what to look for in a pre-owned R65 .
Check the tires for date of manufacture, there's a 4 digit manufacture date molded into the sidewall, should something like this : 4512 .
Which would mean a date of 45th week of 2012 .
Original OEM rubber brake lines, long past their prime .
Worn out brake rotor(s), minimum thickness, .180 inches .
Worn out brake pads, remove the dust cap on each caliper to check, there is a groove molded into the pad material, if it's gone, pads need replacement .
With the bike on the center stand, grab the front wheel and move it fore and aft, any movement, the steering head bearings are in need of tightening/replacement .
Pull the rubber dust seals on the front forks and look for fluid there, seal replacement may be necessary .
Does the odometer work, a real weak point on airhead bikes, look for scrape marks on the metal bezel for the speedometer, to see if it's been disturbed, if it has, chances are the mileage may not be accurate .
Check the front brake master cylinder for leakage where the piston goes into the cylinder, fluid here could be anything from a piston/seal replacement, to a master cylinder replacement .
Check operation of the handlebar controls, the head light and turn direction switches fail internally and cannot be repaired for the most part .
Is the throttle movement smooth, the throttle tube and mating gear are cast metal and wear, causing binding, if the tube and the mating 'cam' are worn, you need to replace the top cover as well, the parts design were changed years ago .
Remove the fuel cap and check for rust in the fuel tank, there is an OEM red liner applied at the factory, so don't mistake it for rust .
The '79-'80 year bikes had dual coils, the forward coil mount is known to break and cause all kinds of electrical problems, the bikes main grounding point is on this bracket .
Check the condition of the rubber boot that covers the speedometer cable, where it enters the transmission on the right side, if it is deteriorated, you most likely have water in the transmission .
Check the neutral indication switch on the bottom of the transmission for leakage, another weak spot, check to see if the green neutral light comes on when in neutral .
OEM Boge shock absorbers, were not that great when new, most likely in need of replacement, they can't be rebuilt .
Gear oil dripping from the final drive onto the rear wheel, the brake camshaft seals are a weak point, may have contaminated the rear brake shoes .
Check the overflow plug at the back of the final drive, they get stripped out and I've seen various bolts/plugs put in there, rather than the plug that should be there .
At 41,000 miles, it would be recommended that the transmission be removed, clean/lube the transmission input splines, dry splines can wear and strip out, costly transmission repair .
Grab the rear wheel and see if there is any movement, if there is, wheel bearings may need attention .
Check all lights for operation, the OEM fuse box is a 'joke' and can cause lighting problems with loose fuses .
That's all I can think of right now, I've had my '81 R65 for 32 years, these are the problems that I've seen on my bike .
