Ben, other then the general stuff, I would try checking the following:
1. Take the magneto cover off and see if every thing is clean and dry. While you're at it, check for any crank movement (up and down).
2. Open valve adjustment covers and see that they're adjusted properly.
3. Check clutch action, it should have some drag but other then that the bike should have good clutch action when the oil is hot.
These are the "weak" points I have found with my bike:
1. The rocker arms are fragile, so it's important to properly adjust the valves.
2. I have had the main bearing behind the clutch falling apart.
3. The coils should be oiled and cleaned especially if you ride a lot in the mud or clean the bike with a pressure gun.
4. The crank bearings last less time then on conventional 4-strokes as they are not submerged in oil.
Other then that, if you maintain it properly it's one of the funnest bikes around.
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Efi
Husaberg FE501 1996