My clutch springs went at about 60,000 miles, causing the clutch to be very stiff, and made it difficult to change gear. The cable was also a little stretched. Replaced the springs with heavy duty EBC parts, and also replaced all the plates with EBC items while it was open; the old plates were still within spec though.
Standard exhaust rotted through within the first two years of owning the bike, because I ride all year round, so I'd say by 30,000 miles the system was replaced with a stainless Motad 4-1 that's still going strong.
Since owning the bike I've covered over 100,000 miles with virtually no problems, rebuilt the clutch and have changed the exhaust. I ride all year round and don't baby the beast. I don't thrash it through the gears, but all day cruising is 80/90mph with blasts up to 110mph when the urge hits me. I commute daily, and also use it for touring holidays and long weekends quite often, covering 1000 miles in three days.
The longest trip taken on her was two up through Europe, covering 8000 miles in three weeks; not a single problem!
This however is what I believe to be the secret to its long trouble free life so far; REGULAR preventative maintenance!
I change the oil and filter every 2000 miles religiously, and NEVER go more than 3000 miles without changing the oil. I use fully synthetic premium quality oil and good filters.
The diff oil gets changed at the same time.
New spark plugs every 10,000 miles along with cleaned after market air filter and balance the carbs. Balancing the carbs should not be skipped, they go out pretty quickly; 10,000 mile intervals I find to be just right for how I ride.
The valve shims get checked/adjusted every 20,000 miles.
Also I've made a habit of keeping her well cleaned, polished and lubricated. I use a lot of WD, and any rusty bits get rubbed down and Hammerited! For an old bike with high mileage, she looks fantastic. All those that say they rot quicker than you can say "Salty roads kill bikes", obviously never clean their bikes. The tail light bit on the rear guard is only showing signs of rust bubbles this year!
If looked after, I believe this bike will cover another 120,000 miles with nothing more than what it's received already.