My M20 has been sitting for some time and as I intend to ride it this coming week changed the engine and primary oils. I drained the oil tank and crankcase and washed the oil tank out with a bit of petrol to remove a small amount of sludgy oil from the bottom of tank and cleaned it with some rag and then blew it with an air gun. I started the engine with oil filter out to make sure oil was returning to tank and it appears very frothy. Am I thinking correct that as the scavenge pump has greater capacity than delivery pump it is simply aerating the oil. I do get a constant bubbly flow from the return pipe.
I haven't really noticed it on other bikes and I suppose had I put the oil filter in it may not have been noticeable. If this is the case I assume once sitting for some time froth should disappear.
Hi Kim...Your assumption is correct..You will get a 'spit and bubble' return once the return side of the pump has scavenged the crank case....Everything will settle down once the engine is running and the oil gets hot...Ian
