john.bebb wrote:Hi Graham
...... if you put your tyre to say 30psi - that is per square inch (actually 'tis better described as per cubic inch but that's a separate apparent anomaly) - that lump of air you put in did not lay in the bottom of your tyre, nor did it float to the top so as to unbalance your wheel, no ... it has equalized!
I understand the logic in this, in a static
situation. However, in an engine, we have a dynamic
scenario and it is entirely possible, IMHO, that the rate of pressure increase under a descending piston is greater than a small vent hole to the timing case can cope with - too much gas trying to escape through too small an opening in too short a time.
I have a Mk2 engine in my bike, which was totally rebuilt less than 1000 miles ago. It has a Morgo oil pump fitted. (I bought the bike as such.)There is a massive steady pressure from the breather pipe with the engine running. With a long clear plastic tube attached, rising upwards from the breather, there is a lot of emulsified oil/water vapour droplets (a.k.a. 'mayonnaise') which forms in the tubing after about 200 miles. It then has to be cleaned out.
I suspect that the Morgo pump adds to the problem due to the amount of additional oil flow. Another symptom of this, it would seem, is a difficulty in sealing the flexible oil return pipe on to the brass pipe on the engine. There's a persistent drip. The vent cap from the oil tank also 'weeps' a fair amount.
(The oil tank is a standard FH tank due to the engine being fitted in an FH frame.)
I wonder if a breather vent from a rocker cover would help...does anyone have any experience of this?