Hi all,
My Dad has a 1971 750 Commando with a 2-1 manifold and Concentric Mk1 932 Carb, can anyone recommend jet sizes for this setup, standard road use.
Kind regards
Ian
I'd go bigger on the main…
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.
Commando Jet settings
Thanks for the advice guys, gives me a starting point.
Kind regards
Ian
Jet Sizes
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.
Jet Sizes
Thanks fir the advice Phil.
Kind regards
Ian
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