duTch..My thoughts exactly, then I noticed the gear lever was missing and getting a liitle bit of insight into esteemed member GB's sense of humour, it all clicked. Mischievous or what?
Looking at the two bikes a little closer, the timing covers differ. The custom bike timing cover has a flat bottom with the piled arm logo, the other cover is plain, with no piled arm logo but with the three bolt bottom, a later improvement. My Longstroke basket case cover has 3 bolts and a logo, so there's one for the cognscenti to explain. Maybe the styling difference between a cheapo A7 and the more upmarket Star Twin.
I commented they had no oil in them as there is no sign of an oil drip patch under either of them, a rare sight indeed in the real world.
Swarfy.