Just read this thread from the beginning. I reckon Col's problem of deposits on the plain plates is more down to the poor quality of the friction material or bonding adhesive. For material to be leached off by lubricant in such a short time is not how these plates usually behave. A non bargain if ever there was one.
For those folks having similar problems with the earlier S/A 6 Spring clutch and its penny pinching design, I've noticed this contraption also comes comes in various guises adapted to fit the models in the contemporary B, M and early C range. For example there are varying depths of clutch basket, flat and dished pressure plates, corresponding different numbers and combinations of plates and clutch centres with different styles of driven tabs. Plain Clutch Plates also vary in thickness, some pattern types are extremely thin. Add to this the wear that takes place, notching components that should slide and there you have a recipe for a clutch that sticks or slips.
If you have a problem with this clutch it is worth checking that the basic parts are correct and not an assortment of bits from different models. Lower powered models from the other ranges have less plates for starters. A previous owner may have fitted whatever was to hand, and if the bike came as a basket case, nothing can be considered to be the right parts, and yes, ebay sellers haven't a clue either so be careful. That Rocket Pressure Plate could have started life on an M20 or C11....certainly not the right part.
Set up correctly the 6 spring pressed steel centred clutch is fine, but why BSA moved from the superior Plunger type 6 spring robust centre design can only be down to the cost accountants. The later 4 spring design cribbed from Triumph addresses most of the failings, going back to a solid or cush type centre but as here can still be problematic for the simplest of reasons. Use the "oil flicking past the hole" fill method to run the primary chain in oil without overfill allowing a high level of oil to enter the clutch.
Swarfy.
