KZ650 General Carb Questions

1981 KZ650-CSR w stock Mikuni VM24 accel pump carbs

The 81 650 gets 62 hp. The 82-83 models get 67 hp.
I'm fairly sure the primary difference between the bikes is the carburetors: the later CSRs have Mikuni BS32 carbs. The stock VMs are known to be jetted lean from the factory. (1) Is the same thing true of the BS carbs?

(2) Any idea how much the hp is bumped up after rejetting either type?

The KZ750-4s have the BS34 carburetors.
I'm fairly certain these will physically fit the 650:
the airboxes & carb holders are the same as on the 82 CSR.
(3) From a carburetion perspective can these be used on the KZ650?

Particularly for those who have the aftermarket exhaust &/or pod filters:
(4) Wouldn't it make sense for them to get some BS32 (or BS34) carbs?

Thanks for any input.

The KZ750-4s have the BS34 carburetors.

Only the GPz750 models have the BS34's, all the rest use CV34 Keihin carbs.

Hmm, I think maybe the 750L used BS34's also, it was sort of a standard GPz

The answer to your question about bigger carbs is YES! I replaced the stock vm24 carbs on my 77 with vm26 carbs from a GS750. I've never had the bike on a dyno so I don't know HP numbers, but the gain was extremely noticable. You could easily replace with stock carbs from a kz750, or even find a set of vm26 or vm28 from a kz900 or 1000 (or GS750).

The KZ750-4s have the BS34 carburetors.
I'm fairly certain these will physically fit the 650:
the airboxes & carb holders are the same as on the 82 CSR.
(3) From a carburetion perspective can these be used on the KZ650?

I ran a set of CV34's on my B1 for years. Just use the CV carb holders.

As of currently i have a set of z1 28mm mikuni pumpers on my 77 kz 650, the bike has a wiesco kit (710 maby?) vance and hines header no baffle and k&n pod filters, the z1 900 carb jetting is stock, and my 650 rund like a scalded ape through the gears and pulls like a freight train to red line.

anarki650 wrote:

The answer to your question about bigger carbs is YES! I replaced the stock vm24 carbs on my 77 with vm26 carbs from a GS750. I've never had the bike on a dyno so I don't know HP numbers, but the gain was extremely noticable. You could easily replace with stock carbs from a kz750, or even find a set of vm26 or vm28 from a kz900 or 1000 (or GS750).

Can the 26 pumpers run on the 650B1 with stock exhaust and airbox? Or would it run too rich?

They should run just fine. I'm assuming the 26's I got ahold of had stock jetting in them (102.5 main, 15 pilot IIRC), which is the same jetting that I use when setting vm24's for a stock 650 configuration.