I'm back.

Hello Everyone.
I've been out of touch with you all for to a couple of different resons, mostly work related, due to the harsh economic times around the world I have been busier than ever trying to keep our businees on track & our staff occupied. Ironic is'nt it, that you can be flat out doing nothing.
Any how I haven't started the old 850 for about three months, so I cajoled her into life the other day & pumped about half a litre of engine oil out through the air cleaner onto the floor before I realised what was happening.
It appears to me that the only way that this would happen is via the breather located next to the oil pump, which ends up in the back of the air cleaner.
Is this correct or is there other scenarios, and why is this happening?

Mike
Sounds like your bike has wet sumped. The oil in the oil tank will have leeched through the oil pump and filled your engine up.
Check the level in the tank. If it is low then take out the sump plug and collect the oil and return back to the oil tank.
This is a common problem for Commandos, it can be reduced by remembering to leave the pistons at top dead centre after riding.
Stu.

Another problem could be also related to wet-sumping:

If you found your oil tank low and did not check the sump, filling the tank would lead to overfilling, as the running engine cleared out all the oil in the sump. With my 850, anything over halfway up the dipstick with oil leads to oil in the air cleaner.

Thanks for your input gents, I had hoped the non return valve may have eliminated wet sumping, but it appears not.

If the non-return is metal ball to metal seat then a small amount of crud will let the oil seep past, I took an airline non-return which had a steel ball sealing on a rubber seat. I had to modify it as the spring was way too strong but as it was easily took apart this was no chore. Now I get no wet sumping at all and there is plenty of oil flow at tickover.

Thanks kommando, I'll pull it out & see if it's still in working order>