I used to own a '96 FE501 that I bought new and owned for 8 or 9 years. The bike never required anything more than the usual maintenance - valve adjustment, frequent oil changes, etc. I changed the oil every ride with Castrol Syntec 5W/50 full synthetic automotive oil and never had any issues with the clutch (the manual said to use 5W/50 full synthetic and Castrol Syntec was the only thing I could find). I did do some tweeking with the carburator and the shim stacks in both the forks and shock but other than that just rode it. It was always real easy to start hot or cold once I did the initial tweeking on the carb and much easier to kick over than the Husqvarna 500XC 2-stroke it replaced. My only complaint with it was that the suspension damping was a bit harsh (it felt like a motocross bike bike) and getting it re-valved would have fixed that issue. The early Husabergs were a bit crude and cobby looking and but sure worked better than any other 4-stroke of the time. The '97/'98 models looked a whole lot better and gained an oil filter ('96 and earlier just have the screen behind the drain plug) but the yelow tank on the '95/'96 models was great as you could see how much gas was still in it.
The weak points on those bikes was primarily the valve train so be sure and check the condition of the rocker arms, cam chain/bearings/tensioner/sprockets. In my experience, if you took good care of the motor they were fairly reliable. But frequent oil changes - every 5 hours or so - are a must with a capacity of less than a quart. You also want to run the engine a bit before checking the oil level because the reed valve between the transmission and crankcase will let some oil collect in the crankcase when the bike sits for a while - like overnight - and it can look like you need to ad oil when you really don't.
