Following the issues with my mar first having an oil leak, then jumping out of gear, I have removed the oil and refilled it a couple of times.

The first time I drained the remainder of the oil that hadn't already leaked out, then filled it with 900cc / ml of oil.

Following a 5 min ride I left it to drain again over night. After re fitting the detent plunger I went to put the drained oil back into the bike. To my surprise there was only 600 ml in the catch tank ?????!!!!!!

Where are the other 300ml ??

 Out the exhaust?

it either leaked out while you were riding or you processed it through the motor (as lineaway said)

I road the bike for 5 mins round a gravel car park. There was no excessive smoke, and the ground and bike were dry ??

I can only think of three ways you could lose? the oil.     One as stated, crank case seal or gasket leaking into bottom end.

Two when you filled it up if you have the bike on its side it could have come out the gearbox breather above the final drive sprocket, but you would have seen the oil.

Three,  i bet its still in there around the clutch and cush drive , if you lift the front wheel up and lean it to the right it can flow into the gearbox.

 

         Steve.

They are a quirky bike all right. If I had known you only had a ride with no trials usage involved I would have said the same as bisby

In case you are doing it some other way, I recommend you drain the gearbox with the bike vertical

The crank seals were toast on both my older OSSAs.

Those seals are pretty darn old now if original.

A little update -

I've only just got back to looking at the bike , but it has been left with the front wheel up on the bike stand. I tilted the bike both ways, and no more came out. In total I got 700 ml out.

I then filled the bike back up with 900ml of oil with the bike sat with its wheels on the ground.

Following this I immediately drained it back out. To my surprise I only managed to get another 700ml out !!!!???

I can't understand where it could be unless it's passing the crank seals ?

Am I fight in thinking that if the seals are gone then the bike would struggle to run too ??

I put the 700 ml back in and fired the bike up. If started up first kick as it alway has, and road around the garden fine.

Your thoughts please ??!

I have just put a new clutch into mine, i drained the oil out through the drain in the sump (front wheel  on a brick) and left it for 1/2 hour then tilted it side to side a bit, i didnt bother to measure what came out.

Then laid the bike on its side to work on the clutch and noted that there was still some oil left in the hollows of the main engine case. if i had to guess how much id say more than 50ml but less than 100ml.

when i look in the gear box area there is an area in front of the gears where a bolt goes through both halves in the castings, this will act as a dam for some oil.

There is also a respectable area under the clutch that pools oil also.