I have an Amal carb on my 73 Ossa Explorer. There is only one screw on the carb that adjusts air/fuel. My question is: since the screw is on the jug side of the carburetor, doesn't that make it a fuel screw? I always thought if a screw is on the aircleaner side of the carb, that made it the air screw. But there is no screw on that side of this carb. I have received different advice on this issue at events. If I back off on this screw, am I making it leaner or richer? And, what is a good method for adjusting these old carbs, (other than discarding them).

Thanks

I don't know your bike or which Amal carb is on it. One general way to tell is if you remove the air/fuel mix screw. If it is somewhat blunt it is metering air. If it is pointed it meters fuel. I'm sure someone will point out this isn't always true. My Bultaco uses an Amal 627 carb . Turning the screw out leans the mixture. You should be able to tell. Running the screw all the way in with the motor running should make it start to bog down from being too rich. At some point in bike history, they started making carbs where the screw metered fuel. I believe all modern bikes are that way. I hope this helps.

Pete