Although I don't have the 50,000 miles you're looking for, my bike will be hitting 40,000 this week. It's an '04 S model that I've owned since 2007. I purchased it with only 2500 miles on it so I know nearly all of its history. I replaced the water pump shaft and seal at about 14k miles and my last (and only) valve adjustment was at about the same time. It's left me stranded twice and both times were due to a failing voltage regulator. I was not able to diagnose the problem until after the second failure. The fuel pump has never let me down although I do carry a spare. I suspect this is because I loathe riding in wet and muddy conditions and am less likely to have moisture corrosion issues. I still have the original clutch slave cylinder because I can replace the o-ring for pennies compared to the exorbitant expense of the aftermarket slave. I'll have to admit to machining a replacement clutch slave cylinder piston with tighter tolerances to promote o-ring longevity. Since doing that I have not had to replace the o-ring. However, it's only been a few thousand miles.
I ride the bike very hard, especially offroad since it's a rally bike at heart and there are few feelings that rival a standup sweeping gravel road corner with your head out over the front wheel and the throttle pinned. I'll admit to having neglected the bike for the last 20k miles as I have too many projects. It gets regular oil and filter changes but little more. I feel that it's overdue for a valve clearance check and possibly another water pump shaft and seal (I've had the radiator overflow tank coated with oil residue for some time now). My biggest problems right now are the degrading fuel lines due to the ethanol in the fuel and what appears to be a bad throttle position sensor circuit. Once I check the valves and replace the water pump shaft/seal, I'll know if 26k miles is all the poor thing can endure.
08 KTM 320 SXF, '07 Beta Rev 3,
Frankenberg 501, '96 Husaberg FC600, '68 Yamaha DT1, '74 Bultaco Alpina 250, '84 Husqvarna WR400 - My Dad says I've never seen a motorcycle I didn't want to own...