Improving the Norton Commando Clutch
Commando 750s originally came with three plain plates, four friction plates, and a pressure plate with a .230” thick machined portion.
The later 750 models, after engine ##212278, and all 850s came with four plain plates,
five friction plates, and a pressure plate with a .106” thick machined portion. The original clutches tended to eventually gum up and slip.
Option 1: Buy an #06-1339/A Barnett four friction plate set.
Option 2: Buy an #06-3741/A Barnett five plate friction set, an additional #06-0746 steel plate, and either reduce the thickness of the old pressure plate, or buy a new #06-3768 thin one.
Either way, we recommend investing in one of our #04-0373/A NUT, CL.PUSHROD SEAL, COMMANDO, which helps keep thick gearbox oil from coming past the clutch pushrod and gumming up the clutch plates (you can see more info on this item on our site), and running nothing thicker than 10/30 motor oil with no friction reducing additives in the primary case, as all the oil has to do is lube the primary chain (and the primary chain adjusters in the Mk3 models).