[Yinzer]

This is what I'm puzzling about.
Brake rotor side to sprocket side...(right to left)

1) About 1.5" long steel spacer on the outside of the bearing that contacts swing arm.
2) Bearing (#6203)
3) Long spacer that goes bearing to bearing and is about 3 mm longer than where the bearings seat in the hub. (86.5 mm)
3) Middle bearing (#6203)
4) GAP of about 3 mm
5) Sprocket spacer
6) Sprocket bearing (#6205)
7) Short fat aluminum spacer that contacts the left swing arm.

When you torque it down, the middle bearing appears to float because of the gap and too long spacer.
The sprocket side bearing is crushed against the cush rubber but it's much larger than the other 2 bearings, so presumably heartier.
The brake side bearing is the most vulnerable since it takes the 52 ft/lbs as well & is smaller.

This is my 1st bike.
Am I missing something?
My assumption was that there should not be any gaps in order to avoid side forces on the bearings.
Additionally, I'm predicting all bearing failures 1st appear on the right side.

My 1st indication something was wrong was a dragging rear brake.
Turned out it was dragging on the caliper frame.
If all the above is true, rear wheel torque is critical and should not exceed 52 ft/lbs (my guess is 45 is good or at least that's what my elbow likes

[lucky phil]

I looked at the part diagram but stupidly it doesn't seem to put the parts in the correct order in the exploded view. Check it anyway to ensure all the parts are there.

Phil
 

[Yinzer]

Check it anyway to ensure all the parts are there.

Checked that 1st and then my paper copy of the manual.
Nothing on the floor either 

So my wild theory is the thickness of the cush rubber.
It appears to be sitting about 3 mm proud of the hub casting where it is designed to fit into.
If it was flush, that would about do it.
A less thick cush drive would move the sprocket spacer closer to the "floating"/center bearing. (possible taking up the slack)

So...
The center bearing spacer appears too long and the sprocket spacer appears too short.

I'm looking into what might be an easy solution w/ parts readily available to everyone.
Possibly shimming the sprocket spacer with a machine bushing/washer??? (between it and the large bearing)

Also thinking about a hybrid ceramic/steel bearing on the right but I don't know enough about them yet and what side loads they can handle.

[James.]

This is ringing bells with me and it was down to a missing spacer and a previous owner.I am guessing this is a botch by a previous owner.

[Yinzer]

This is ringing bells with me and it was down to a missing spacer and a previous owner.I am guessing this is a botch by a previous owner.

Bought the bike new (means nothing...just saying)
All spacers accounted for.

Left, short one. (aluminum)
Sprocket (one that looks like a truncated cone with insert)
Middle one (inside hub)
Right, long one. (steel/disc side)

What one were you missing? (assuming sprocket otherwise the thing wouldn't even roll)

[James.]

Bought the bike new (means nothing...just saying)
All spacers accounted for.

Left, short one. (aluminum)
Sprocket (one that looks like a truncated cone with insert)
Middle one (inside hub)
Right, long one. (steel/disc side)

What one were you missing? (assuming sprocket otherwise the thing wouldn't even roll)

Mines was a 2007 classic 350 where it was also noisy.I also had a 2019 classic 500 with a worn pushrod camshaft bearing that was put down to a missing spacer from new.