I'm going to dig up this old thread for some advice.
I recently acquired a beautiful example of a 2001 FE501. Got it for a song (and my singing voice is deplorable!) and am researching the issues that the '01's had.
Quick little aside: I actually received a tour of the Husaberg factory when I was visiting Sweden in 2001. During that tour, our tour guide (I believe he was the director of Quality but I certainly can't remember a name) tried to start a random bike in their staging area for the chassis dyno as a demonstration of the electric starter. The bike wouldn't start so he had to help the starter with the kicker. So, the e-starter sucked even while AT the factory!
Anyway, this bike had been disassembled, presumably for a top end rebuild, because the box of parts that came with the bike had new cam bearings, new timing chain, new auto decompressor weight and spring, and a few other new items. Sadly, the owner lost his life in an auto accident that year (presumably around 2012 as evidenced by the registration sticker on the license plate).
My original intention was to install an older 501 engine I have (a 1995 vintage kick-start-only engine) but my research is leading me down another path. Let's examine the issues with the '01 501 engine:
Cam follower bearings - the CFB axles are 7.8mm resulting in smaller needles which, near as I can tell, is the same as what the earlier engines had all the way back to 1989. I have four of those earlier engines and have yet to experience a cam follower bearing failure. Cam bearing failure - yes, but no cam followers. Might be due to the fact that I have spread the hours over the four and none has ended up with a lot of hours. That said, one of the CFB's in this engine appears to be shagged and the corresponding cam lobe shows slightly more wear than the other lobe. As such, this engine will, at the very least, get new CFB's. I will have them treated by Microblue for oil retention and longevity.
Rockers - I understand that the '01 rockers receive pressurized oil. I also understand that the engineers eliminated the oil feed on the later bikes, presumably because reliability was improved more by the larger needle bearings in the CFB's than by the oil bath. My hope is that the Microblue, in conjunction with a steady supply of oil from the oil-fed rockers (and other modifications) will solve the reliability issues and allow me to avoid upgrading the rockers (and the associated cost). Are there any problems with keeping the oil feed to the rockers?
Cam - It appears that the cam is the original (although it has a steel sprocket mounted to it). What cam is considered the best for CFB longevity, hopefully without killing the power of the engine? Also, does anyone see a problem with running the cam without the auto decomp installed? I've been kick starting big Swedish singles since a 1986 Husqvarna 510TX that my father purchased new. I even remove the kicker-activated auto decomp on all of my Bergs because, as long as I've got the manual decomp, I'm good to go.
Valve springs - If I switch to the cam that is easiest on the CFB's, should I still do the DVSK?
Electric start - It's extra weight that I don't need so I will be removing it (and the battery). I assume it won't work without the auto decomp anyway. Does anyone have a starter hole plug laying around that they're not using or will I have to lathe something up?
Counter balancer - There's nothing to indicate that the counter balancer bearing is bad on this engine, and I don't want to split the cases on this engine at this time, so I'm going to run it and keep an eye on the oil. If I like how smooth the engine is (and I've got plenty of early engines with no counter balancers to compare it to) I'll think about upgrading the bearing at a later date.
Stator - Has anyone done a wet-stator conversion on one of these? Any issues sealing the stator cover? Thumper Racing did a wet stator conversion on my 660 ('96 vintage 600 with 100mm bore) when they put it together and I've been struggling with oil leaks. Maybe it's better with the stator mounted to the side cover?
Carb - No-brainer. Going to swap to a 41mm Keihin. I have tons of experience making the earlier engines run well with this carb. As a result, I have a growing collection of Dell Orto's laying around.
Thoughts from the Husaberg collective?