1971 Commando Jet settings

220 main jet, 106 needle jet, needle clip in middle groove, no. 3 slide according to the Amal settings list for 1973 (suggested settings for unknown bikes).

I usually find these to be fairly close to being right, but the slide can usually do with a fraction more cutaway (3.25 or 3.5)

john

I'd go bigger on the main jet. And, if you can get a float bowl with a larger fuel inlet - so called 'dope bowl'. Otherwise they run weak at high revs and loose power.

The 650 Mercury ran a 930 Concentric with a main jet of 280. I believe with no air filter.

I put a 932 Concentric on my 1972 Commando 750 and used a 270 main jet with K&N oiled gauze filter. The Concentric came ready to use (apart from the air filter) from a Carb specialist.  I had previously given him the model/year of my Commando.  The bike ran fine and easily gave 60mpg at high cruising speeds.

220 was the jet sizes for the twin 930 Concentrics that I took off my bike.  As a rule of thumb, if you increase the choke size and/or head down the single car route you need to increase the main jet size of risk a weak mixture.