Background

So I have a Ducati ST4s 2001 that seems to suffer from premature main bearing failure. The bike has been standind for a while now since I haven't had a place or time to take the engine apart. The engine started making supercharger noise even though I'm pretty sure there isn't one installed. I headed to ducati.ms forums and searched around the web and found this thread. There was a Youtube video of a similar bike with bad main bearing. Also another sound clip of one that was suspected to have the same issue. That didn't look good since my one had pretty much the same sound it was making. It wasn't the clutch pressure plate bearing as it makes the same even without the clutch. It didn't seem to come from the valvetrain system either and the pitch was pretty low to be caused by any small bearing. There's only 40k km on the bike so many things seemed to match to the previous cases.

I figured the only way to find out for sure is to remove the alternator cover and flywheel and test if there's any play on the crank. That would have been a clear indication but without any play things would get a bit more complicated since the bearing has to be inspected as there's still the noise.

I'm no mechanic from my background but I've been doing the basic belt change and valve adjustment jobs for my ST2. I've never taken any engine completely apart so I was a bit concerned whether I'm up for the job or not. I already had most of the required tools, I'm quite pedantic by my nature, I've been interested in mechanics since I was a kid and taken many things apart, maybe with a bit various success on the re-assembly side, I had the books that should cover the job pretty well and finally got an own garage so I decided to take the challenge.

I also thought it would be a good idea to document things and a blog seemed to be a good option compared to millions of notes in the garage with oily fingerprints on them and pictures here and there. Besides you never know if someone else finds the blog useful or some other way interesting :)