Keihin FCR carbs for KZ1000b

Anyone have any experience with the FCR's on a kz1000?
Are they street-able on a close to stock motor?
mm Size per motor modifications?

Doing an AC sanctuary style resto-mod. My motor is 1977 1000B. Will be doing full rebuild... Not sure on size of piston kit, and other mods yet. Wanted to figure out carb size per motor mod specs.

They will be mostly wasted on a stock street engine. Flat slide carbs need a strong vacuum signal to meter correctly at low RPM. A stock engine will not generate a strong enough vacuum at low RPM even in a the smallest venturi that FCRs come in. Results will be poor at low RPM making it difficult to tune for the street. If you do a mild engine build with perhaps a 1075 kit, 10.25/1 comp, cams, port and polish then I would suggest 33mm or 35mm if you plan on racing. Mikuni RS carbs will deliver similar performance for a fraction of the price. but again they will need a warmed over engine to function well.

As far as I'm aware the only two US distributors of FCR carbs are not making kits for KZ1000 which means it will have to come from Japan. considering the state of the world right now ordering from Japan could be a struggle.

your going to want be in the 32mm range and no bigger than 34mm.
i re-spaced a set that had been on a smaller cc zephyr in japan, for use on a kz1000 .but i have never heard if they have been put into service.
as Doctorot stated you are going to need the engine that needs bigger carbs to be able to use any carb larger than 28mm.
so build accordingly,

leon