geo46er said:Hi plj850,
In a perfect world your one-way valved engine breather tube pumps no oil to the tank. During the first couple of piston downstrokes the air is pumped from the cases establishing a slight vacuum which reduces pumping losses and keeps all the case joints and seals nice and oil tight.
In the real world the bike has been sitting a week and the crankcase is half full of wet sumped oil, the first couple piston downstrokes send a gusher of oil up the breather tube (72 models). Once the engine is running piston blow-by reduces or completely eliminates the case vacuum, and directly contaminates the oil in the engine with moisture and other nasty gases, then indirectly contaminates it by being vented into the oil tank.
Regarding your observations of breather output, when the engine is running oil is flying all over inside, therefore it is beneficial if the exhausted breather air/oil mist passes through somesort of condensor/oil trap. Venting the breather into the oil tank was Nortons answer.
Ahh problem is my bike never sits in the garage for a week its my main mode of transport never had a car licence...good points made though informative for all