1977 KZ1000a Jetting

Hello I have a 77 13000miles with a kerker exaust and pods with main 115 jets I am looking for an airbox system but until then can someone give me a jet recipe that will get me by, the bike runs decent but feels a slug, hit the choke at 55-60 and it feels like Nitrous lol I am hoping a 125 or 135 main but I am not even sure what sizes are offered this is my first KZ thanks for the help

I have a 78 kz1000 with v and h pipe and pods bored to 1075 and I am running 127.5 mains and they are working fine. 135 might be too much. Start with the 125,s.

pscycle wrote: Hello I have a 77 13000miles with a kerker exaust and pods with main 115 jets I am looking for an airbox system but until then can someone give me a jet recipe that will get me by, the bike runs decent but feels a slug, hit the choke at 55-60 and it feels like Nitrous lol I am hoping a 125 or 135 main but I am not even sure what sizes are offered this is my first KZ thanks for the help

Stock main jet is 107.5.
115 is already 3 sizes over, and would suspect being adequate for Kerker 4>1 (even without baffle) and pods (if fitted instead of stock airbox with filter).

The definitive analysis for main jet sizing is spark plug reading after high speed throttle chop test.

Usually done roadside, so take along a ratchet and plug wrench socket AND a short length of fuel line that fits snugly over a spark plug in order to remove and replace the plugs without burning fingers.

Good Fortune!

Ok good stuff thanks guys I thought I had read somewhere that 115 were stock I did find an airscrew backed way out on #3 but I doubt that that is why she surges so hard when I hit the chioke I choke her and she runs like a beast.

pscycle wrote: Ok good stuff thanks guys I thought I had read somewhere that 115 were stock I did find an airscrew backed way out on #3 but I doubt that that is why she surges so hard when I hit the chioke I choke her and she runs like a beast.

Am pretty sure the 1977 KZ1000-A1 stock VM26SS carbs have a bottom-located pilot mixture adjustment screw, and not a side-located pilot air adjustment screw.

Normal pilot screw position is 1¼ ± ⅛ turn out from lightly seated.

Turning the bottom-located pilot mixture adjustment screw out counter-clockwise (further away from its seat) enriches the mixture, and turning the screw in clockwise leans the mixture.

Whereas, turning a side-located pilot air adjustment screw out counter-clockwise (further away from its seat) leans the mixture, and turning the screw in clockwise enrichens the mixture.



The pilot circuit influences the fuel mixture up to 1/4 open throttle position, where size of the main jet doesn't influence the mixture.

Where adding choke improves performance at wide open throttle, the reason is something else besides the pilot jet or the pilot circuit.

Good Fortune!

Thanks for the diagram I just checked my pilot mix screws they are all between 2 and 2 1/4 out Im betting that's the problem The carbs are absolute spotless so I bet whoever cleaned them just reset the screws wrong. Ill put the bike together in the morning and see how it runs at 1.5 1.75 T.O.

pscycle wrote: Thanks for the diagram I just checked my pilot mix screws they are all between 2 and 2 1/4 out Im betting that's the problem The carbs are absolute spotless so I bet whoever cleaned them just reset the screws wrong. Ill put the bike together in the morning and see how it runs at 1.5 1.75 T.O.

Might help, but only with side-located pilot air screws.

Will probably make matters worse with bottom-located pilot mixture screws.

Good Fortune!

Hey JimB What elevation are you at? I'm at about 4500 feet, and I am trying to dial in my carbs on a stock 1000 with pipe and pods.

Here in Denver, at around 5000 ft to 5300 ft MSL all the time.... I am running 115.0s with #20 pilot jet, mixture screws are about 1.25-1.50 turns out.
The KZ1000 has 4 into one headers with stock Denco street baffle and 2 into 1 air filter pods... (two large pods sharing two carbs each).
My mixture is still a tiny bit rich from looking at the plugs after 100 miles.
If you are running nearly same config, your piston seal is good, valves are good, ignition is correct.... and you need the choke on for full power then who ever said your carbs a spotless clean is badly mistaken.
You must have fuel starvation at WOT.
Can't be the fuel delivery because that would effect the choke... your main jet fuel system in the carbs must messed up somehow.

I was running 117.5 mains and 17.5 pilots when I had mt 2/1 pods and 2/1 crossover exhaust. That's with VM28's. I would suggest 117.5 on the mains and 17.5 pilots too with the 26's. Be sure to get Mikuni jets. The others are drilled differently. 125 would be to big IMO.
Steve