Thanks to all who answered.
No, the crank does NOT ride on the crankcase housing. There ARE inserts. They just tell you that they're non replaceable. I'm old school too. You might have to spec out your own, but i have no doubt you could find something that would work. Even if it meant having the main
journals on the crank ground down a little to match whatever you could find for bearings. where there's a will, there's a way.
The bearings are NOT installed and then line bored. from a manufacturing standpoint, this would make no sense at all. The housing has to be line bored. why in the world would you make the inserts so sloppy that they needed to be line bored also after installation. Not to mention; the babbit surface of modern bearings is typically less than .001". No room for line boring there. Bearings haven't been line bored after installation since Ford flathead V8s.
No, this (I suspect, and am seeking confirmation on), is just a giant line of bull$@!t. True; at the moment i have no need to replace any main bearings. i'm just seeking correct information. If someone could come up with a plausible reason why they CAN'T be replaced, i'd love to learn about that. I'm not claiming to be (and do not wish to be perceived as) a know-it-all, but I've been building my own M/C and automotive engines for 40+ years. I was previously employed by an engine parts warehouse, serving machine shops all over the northeast. One of my main responsibilities was to identify parts for obsolete machinery that would serve as suitable replacement parts, with or without some minor (or sometimes major) modification. (did you know Corvair pistons will work in a flathead Harley?) I'm just saying . . . I need to know why these bearing "can't" be replaced. I seriously doubt it. Yamaha may have made no accommodations to replace them. I'd like to know why. Nothing magical going on inside these engines that is obvious to me. I'm always open to enlightenment, however. So anyway, what I'm actually hoping for is for a legit Yamaha tech to give me the story that Yamaha has come up with on this, and can tell me the story without making me laugh.
And just to address the obvious error; there are no roller or ball bearings used with this crankshaft. Someone must be looking at their Harley manual.
Anyway, thanks again. Hoping to hear more.
also, . . . . it breaks my heart that this site is shutting down. I hope someone with the needed resources sees fit to rescue it. There are other Roadstar sites out there, but not like this one.