The pump is a screw pump, so very unlikely to be completely broken, not many moving parts there. What nobody tells you is that you have to turn it CLOCKWISE. Also what I didn't see on the tech pages was any mention of the extremely useful bleed screw. On the top by the inlet there is a screw which I can see serves no purpose other than to let air out of the system.
I doubt the vacuum from the carbs assists at all, it's going to be less than the gravity effect from the reservoir and I tried sucking as well as screwing and nothing spurted out.
Eventually I got it to work with vigourous spinning of the pump and tilting it at different angles, tapping, and bleeding off the air with the bleed screw.
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MC28 SE -sold-
MC21 with RS250 engine -for sale-
MC21 race bike -soon for sale-
