DTT, not scolding you, just repeating some information for others who might be tempted to buy something unsuitable. Even if those carbs are genuine Keihin PWK's, they are not PWK32's. KEIHIN DOES NOT MAKE A 32 MM. PWK, AND THEY NEVER DID. That's a PWK28 or knockoff thereof with the venturi bored to 32 mm.
The bore job is done because the PWK is a dedicated 2-stroke carburetor, and 2-stroke motors require big, fat needle jets. Keihin doesn't offer optional needle jets for PWK's. The cheapest way to get a NJ that's close to lean enough for a 650 cc. 4-stroke twin is to punch out the PWK28 and use big, thick jet needles. And that still leaves the cruising range mix too rich.
As far as I know the first vendor to hustle punched-out PWK knockoffs for old 650 and 750 twins was JRC Engineering, who offered the lousy things for Brit bikes; the first ones I saw had been removed from a Triumph after the owner had installed them, given up trying to get the bike to run clean, and turned the job over to a local shop. I don't know if they managed to get the owner to accept that he'd been burned and needed different carbies or not.
As far as carb options are concerned, you'll get the best performance out of OE vacuum carbs if you retain the still air box. If you just have to have pods, the Mikuni VM series is the most economical choice. There's plenty of information available on tuning, seek and find. Avoid discount vendors who claim to install application-specific brass and wind up costing you more money than you'd have paid to somebody honest. If you want a trick look and crap performance, go ahead and hang velocity stacks on vacuum carburetors. Most guys who do that don't know the difference, maybe you won't notice the performance loss either.
