The oil from the oil tank seems to be wet sumping, and then dripping out of the timing case outer cover at the gearlever hole. There is a lot of freeplay on the gearlever shaft where it comes through the hole.
Obviously I need to take a look in there - but I wondered if anyone had any thoughts on this? Are late C15s prone to wet sumping? Afaik this 'rebuilt' motor has a new oil pump (based on the fact that the remains of an old pump that came with it..... )
From the parts book I can't see any bush or oil seal associated with the hole where the selector shaft passes through the outer cover. Should there be something there?
I'm not sure the part's book that came with the bike is actually correct for the year. Catalogue No. 5119. I can't see that there is later one?
Thanks
Gear pumps often bleed oil through into the sump , especially if sitting unused for a while.
Some people leave the little sump plate loose/off to catch any oil and recycle to tank.
I use my c15 every 3 or 4 days and sometimes it feels as though oil has drained down.
Use it regularly.
Once started, it won't take long at tickover to send it all back to the tank.
It could be this engine oil bleeding through the inner cover out into the outer cover and past the gear spindle.
There is no seal there.
Have you checked gearbox oil level? If it's too high the excess may leak through gear lever shaft.
To check for wet sumping remove the filter cover and put a container beneath it, leave it for a few days and see how much oil accumulates in the container. My B40 leaks about 75cc in a week.
Wouldn't think that wet sumping would leak out of gearbox shaft as that would mean the sump was half full of oil, plus the side points engine (I assume yours is side points as it's 1966) seals the inner and outer cases where the gear shaft protrudes,
I've taken the outer timing cover off - which was full of oil up to the gearlever shaft. The oil is entering through this pinhole near the bottom of the inner timing cover. Is this pinhole a BSA design feature (I think there is one like it on my 1968 A50 venting into the chaincase)?
When I first saw it I thought it was the case having gone porous - but having now seen the piccie on my pc, it looks a very neat hole - as though it was put there by the factory.
Hopefully someone will correct me if I'm wrong but I believe that's a drain hole for any oil that accumulates in there from the timed crankcase breather that comes through the crank. The oil drains back to the oil pump through it and the air pressure is vented through the breather in the top of the crankcase.
That's my understanding too.
The only oil in the outer timing case should be from the breather.
If its a dizzy engine the outer timing case should only contain oil from the breather, however if its a side points engine the rear section of the outer timing cover contains gearbox oil as it forms part of the gearbox.