Boxerworks.com

11/81 R100RS.

Riding along today, a slight whirring noise then when accelerating from 80-100kph a grating noise, no increased road speed and elevated rpm. Clutch in, backed off and cruised to the verge. Gear change felt fine, engine felt fine, clutch lever all good. Headed 5km home, same happened again so I left it in 2nd. Got home, drained the trans. Usual collection of stuff on the magnet. Swapped bikes and headed back for work.

So home from work. Too late to fire it up and run it with the rear wheel in the air to assess for noises. I had a good look at the trans oil however, and found this. The magnetic drain plug only had soft fuzz, the usual soft fuzzy non sharp benign stuff.



I'm guessing it's the transmission.

Other than the picture of whatever that is (is it hard or soft?), I'd say the problem is the clutch.
With gears, you won't have the motor rev without corresponding increase in speed unless you were missing teeth on a gear which would produce much more debris in the trans than "the usual collection of stuff" on the magnet, or a bearing is completely destroyed, which would cause a misalignment of the gears causing a huge whine and difficulty shifting.

Bad clutches show slipping more in higher gears than lower, as you don't get the torque multiplication in the upper gears, so you're just depending upon the torque of the motor.

just my opinion.

It's hard, flat steel...sticks to a magnet.

I took the bike for a 50 km spin a couple of days ago. No noises that caught my attention then, no clutch slip at all.

This was over a 2 km distance, a slight whine (in an 80kph three lane tunnel) then the noise and other symptoms as I was steadily accelerating to 100kph. I'm wondering if something has snapped off, made a noise as it was "processed" thru something, eg gears then dropped to the bottom of the box. It wasn't on the drain magnet with the "usual" fuzz.

Maybe the cage from the front bearing.
Would cause the whine. And the input seal would go bad, allowing oil onto the clutch.
Just guessing.
The metal in the picture doesn't look like a tooth. Looks thinner.

I'm seeing a piece of mangled metal about 20mm. Can't make an estimate of the thickness. I know it wasn't on the magnetic plug but is it, in fact, attracted to a magnet. This will tell you if it's steel or... well... not steel which, in the interior of the box, pretty much means aluminium alloy. If it's steel, then it's probably a gear tooth. If not, it is something knocked off the case somewhere... in which case, it is a pretty sure sign of another problem.

In any case, I think it's academic. With the problems you have, I can see no alternative to dismantling the box to see what gives. Once you get in there, you'll find out where the problem is and where to go from there. I would say, though, that the prognosis isn't brilliant. The chance of collateral damage inside the box is quite high and it would be quite a reasonable response to simply source another box.

Rob

What is the oil drip gutter made of that is at the top of the gear box? May be it came unscrewed.

PAS wrote: ↑Mon Oct 26, 2020 10:56 pm What is the oil drip gutter made of that is at the top of the gear box? May be it came unscrewed.

That's where ME 109 has his money. I'll get to it later this week.

Not mine...

Thats my picture from adriders.

If you can clean that piece up, and post clear varying angle pics of it, with a metric ruler for scale, I'm confident I can tell you what it is.