My 2005 Buell XB12S has approx. 13K miles on the clock. I have used Castrol Edge V-Twin (20W-50) oil for approx. 4K miles (since I've owned the bike) and before that it was changed with exclusively AMSOIL 20W-50 which I cannot find anywhere .
Anyhow, I'm concerned that the motor has become increasingly noisy. I know most overreact to assume that it's rod-knock, but I used a mechanic's stethoscope to pinpoint the noise to the crankcase. It's not the best, but here's a vid:
Sounds just like mine did, changed cylinders and pistons and it seems fine now. After pulling it apart the cylinders were very out of round and larger than specification so theory was piston slap.
Primary chain was within spec per the service manual.
Piston slap could be a culprit. However, generally piston slap will decrease after the motor has warmed. The "clunk" stays even after the motor has been running for several miles.
Bearing failure seems unlikely since the noise doesn't worsen when I rev the motor...
Does the video kind of draw the noise out a little more than it sounds in person? I just videoed mine to get some input on a noise like you did. Yours sounds like a deeper noise than mine does, mine is a little more clattery. Anyway, if I could piggyback on your thread, here is a link to the noise mine makes, I'd appreciate any input. The camera picked the noise up and it sounds a lot worse than when your standing by it.
It might wreck the stator and you would probably know about that by now, but it is probably just rubbing on the cover. ALl you need to fix it are a new gasket, fresh oil, loctite, and the locking bar so you can keep it from turning (and a great big torque wrench).
While in there you should replace the chain tensioner because it is pretty cheap and you are that far in already.
You can test for a loose crank nut by putting the bike in gear with the engine idling. Ease out on the clutch while holding the front brake and the noise should lessen as you put load on the drive train if the crank nut is loose.
If a loose nut turns out to be the case, be sure to clean the crank and nut threads thoroughly using brake cleaner or similar, apply LOTS of liquid (not paste) red Locktite, and use the updated torque spec for the nut (~250 ft-lbs IIRC).
If the nut is not loose and you still suspect the crank, change the oil and inspect the drain plug for excess metal filings. It'd also be a good idea to cut apart the oil filter and check it for filings. If you don't find anything there, I'd keep riding it and not worry about it.
I just had my sidecover off to fix the primary lip that broke, I wish I had checked it out then. I've been off it all winter and had forgotten about the noise. I did have a socket on the nut to rotate the engine and I know it's not physically very loose, but it could be looser than 250FTLBS. I keep a pretty close eye on my oil, the only one I have had filings in is the primary oil before the clutch lip failure.
Ow Hugh... that hurts my heart to hear those noises...
Oh, it hurt my ears too. That video was just over a year ago. I tore my engine down a week or so later to find badly scored cylinders and pistons and a front rod with ~1/8" play on the crankshaft. After debating for about a month, I bought a low-mileage 2009 XB12R engine off ebay, complete with ECM, oil cooler, etc. and swapped it into my 07 Uly. I did have to buy a 2009 Uly wiring harness to make it work out.
I was able to sell many of the parts from my old engine so I recovered about half the cost of the "new" engine.
A year later, I'm very satisfied with the bike and it's still running great.