I am finishing up a rebuild on my 1982 XT 550. I noticed that the balance shaft seems to slide back-and-forth to the point where the “breather” as it’s called on the end of the shaft will touch the backside of the clutch housing. I called a few motorcycle shops, and the one that would talk to me told me that that’s normal, but I find it hard to believe. The movement would be the right hand bearing sliding in and out of the right hand case. Is this really normal or is there something missing that’s supposed to hold that bearing into the case? I can tell someone had this apart before and this wouldn’t be the first thing missing I found in there.

Do you have a seal installed between the balancer bearing and the balancer gear?    I have a 1985 XT600 manual which I believe is similar and the exploded views show a seal but no retainer plate or anything. 

Oh yeah, I see that on the 600, but the diagram on partzilla shows that it goes bearing, gear, breather, lock washer, nut for the 550. 

www.partzilla.com/catalog/yamaha/motorcy...0j/crankshaft-piston

Makes sense that it would have something to retain it from sideways movement.
I'll keep digging.
No circlip in the case, maybe a small one?.
This pic 'i think'? looks like a circlip on the shaft against the bearing, but maybe me seeing things.
Should there be a step in the case to stop the outer of the bearing wandering.
Is it a needle bearing.
Good pics in the listing below.
Is there a button in the clutch cover to limit sideways--that doesn't make sense, even yamaha sense.

eBay item number:403958498194

Ok, dummy Me, found an ebay pic so what i'm looking at in first link is the part that runs in the roller bearing. Sorry, back to the drawing board for 'me'.
eBay item number:175748469836

The left end of the shaft goes into a blind hole so there’s nothing on the left end holding it in, the middle part is sandwiched between the bearings, all I can think is that there must be something to hold the right bearing to the case. I suppose tonight I’ll pull the clutch back off and have a look for myself

Just googling away & found this--which i guess doesn't help but looks like it is limited to what sideways it shows, but ok what's doing the limiting. Is this video you by any chance. Not sure how old it is without looking. Cheers.

Oh--11 years old haha but i guess nothing changes in respect of what you're talking about. I rebuild an SR250 with ballancer at work but that was a lifetime ago but possibly similar--get it timed right or it hits the conrod-bigend. But that's not helping sorry.

www.youtube.com/shorts/Iw40LSvw-Rk

www.youtube.com/@grecoa7

Good videos this guy does but i guess nothing you don't already know or have done.
I'm no help sorry. I'd better go mow lawns.

Looking at that case picture on ebay, it shows the bearing is pressed in from the middle of the cases, so the bearing can’t be sliding outward to the right. I wonder if it’s the wrong balance shaft? Like maybe from a 600… I hate to tear it all the way down and split the case again. It’s nearly 100% together. Did I mention that the weight in the balance shaft looked like it hit something at one time? Like someone didn’t get it in sync with the crank and they ran into each other… no damage on the crank or con rod..

No that video is not mine. It has way more play than that