Amal 928 Air Screw ?

[A10 JWO]

Fitted a brand new 928 on my 650. It did not want to run or start well with the choke on. Started well without choke just tickler. Settled down to a pretty good tick over. I adjusted the air screw in and out and it did not affect the tick over or revs. I have not road tested it yet with the carb on. Any suggestions.

[bsa-bill]

having similar problem with my (389 ! ) not sure if I've cured it yet as other problems came to light, but it did look as if there was something in the pilot jet which I blew out with an airline.

[muskrat]

G'day JWO.
Is it on an iron or alloy head? On alloy heads the concentric has trouble with float/fuel height due to the downdraft angle of the manifold (iron heads no problem).
The new concentrics have a pressed in pilot jet opposite the air screw with a 0.016" orifice. Hard to get to and hard to clean. Wouldn't be the first time a new Amal had crud in there.
It should also have a "stay up float" which can be adjusted to give correct fuel height of between 0.170" - 0.240" from the bowl/body surface adjacent to the idle screw. This will also affect pilot adjustments.
Cheers

[A10 JWO]

Alloy head, thanks Musky. Will get the cleaner out. Regards.