R27, whining diagnosis?

[Oldpaint]

I was out for a ride earlier this week on my 1963 R27. About 45 minutes into my ride on a hot day, I began hearing an intermittent, high-pitched screeching sound. It sounded like it was coming from the rear of my bike. Not knowing what it was or where it was coming from, I pulled over a few times, didn't hear anything and then started again. I rode for a few minutes and didn't notice a consistent pattern, but here's what I can say. The screeching would occur (sometimes) when I was changing into a higher gear. However, sometimes when I went into fourth from third, say, at lower revs, the noise would disappear. As an experiment, I put the bike on the center stand and then ran through the gears, but it didn't trigger any screech.

Any ideas? Is this a wheel bearing going bad? Brake issue (even though it happens when I'm not braking)? Splines?

Any advice on the proper diagnostic sequence is appreciated.

[schrader7032]

I wouldn't think rear splines unless they are incredibly unmatched and moving around. Try changing final drive fluid...not sure if you have a magnet on the drain plug...you could inspect for bits of bearing breaking up. Bearings seems most likely. Probably should pull the rear wheel and look at the splines, try some grease. Then move the bearings around with your fingers...see if you feel anything unusual. Also, before taking things apart, grab the wheel on opposite sides and try and rock the wheel around...there should be relatively no movement.

[c.d.iesel]

Got oil in the motor ?

Got oil in the gearbox ?

Got oil in the rear drive?

easy to check

when were these lubricants changed last ?

history of the rear brake and rear wheel bearings ?

[Oldpaint]

Thanks for the advice. I haven't had a chance to check this yet. I was afraid I might do some damage if I kept riding and it's stashed a few miles away. Now I'm headed out of state for vacation (four wheels) and won't be back for two weeks. I know there was oil in the crankcase but didn't check the rear drive (everything was too hot), but the fluids were there before I started out on the ride. I'll post an update if I figure it out what the problem is. Thanks again.