Re: how to flush out banshee crankcase?
I would use something light, like kerosene, to cut the oil and give the sand nothing to stick to. Then stick the nozzle of the garden hose in there and flush it as best you can. Then another round or two of kero to displace the water, and some 2 stroke oil on each bearing before assembly.
I don't think a brief water bath will hurt a thing, and you're gonna need something under pressure to get any debris out of the case. Kero by itself isn't gonna float sand out.