77 KZ1000 Carb tuning

Ok I just bought a KZ1000 with dyna coils, kand N pod filters, and a vance and hines pipe with baffle. The bike starts and runs decent but there are a few problems I want to address over the winter. The bike takes 10 min to warm up and run well??? Around 6k RPM it falls on its face and sounds like it is choking??? There is slight popping from the exhaust while decelerating??? The engine is original but I am not sure if it has been rejetted. The spark plugs look to be rich to me. I am in Nebraska at about 1100 Ft above sea level. I am going to tear the carbs down and clean this winter where is a good place to get carb gaskets and any recommendations on jetting? Thanks for the help

If not already addressed, issues might not result from carbs, and could just as well be ignition or compression related.

Even perfect carbs cannot compensate for deficiencies in ignition or compression. Any carb tuning should be addressed only after a full tune-up of the other components. Including at a minimum, new plugs, points gapped and set, timing, and valve adjustment, and good fully charged battery.

Need a good fat properly timed spark (look at the spark with plugs removed). And full battery positive voltage should be reaching coils.

Timing should be set using a strobe type timing light, and watch the advancer move back and forth while varying rpm.

Perform compression check (hold throttle wide open durimg test).

When all the above items have been attended to, and if the problem still persists, then it's time to address the carbs, starting with assurance of ample clean fuel supply (including inline fuel filter), and service floatbowl fuel level measurement using clear plastic tube method. Then sync and pilot air screw adjustments, and would also read plugs after high speed throttle/ignition chop, all before disassembling the carbs.

The peanut gallery has spoken. :laugh:

Good Luck!

Z1E is an excellent source for carb parts.

Plug reading after high speed throttle chop gives visual evidence of what's happening inside the combustion chamber at wot when main jet size is a determinative factor. This information is very helpful in deciding whether there's any need to increase or decrease the mainjet size. The existing mainjet may already be just fine.

Don't forget to clean and lightly re-oil the pod filters.

Good Luck!

I dont have points and I have checked the compression. I am looking for thoughts about jetting if anyone could be of help.

Do you know the jetting on your bike?

I think i've had similal set ups on several bikes and the idle was 17 and the mains were 117 with the needles in the third slot.
I run a lot of gear but that should work.

I have yet to tear them apart to see what I have. Thanks a ton for your input.

Had the exact same problem (stopped pulling at 6-7K rpms) with my KZ1000.

Bigger main jets fixed it. It had stock jets (112.5). :S

Can remember what size I ended up with, but now when you hit 6K it takes off like I flipped on the nitrous or something.

I know the pilots are 20, but the mains are what resolve the problem.

are the carb's stock or is there a set of 29 smoothbores on it, also is the engine stock or is it kitted. it sounds to me like it has stock jetting in it because of the symptoms you have described.

how can I tell what carbs are on it? I believe they are stock. What does smoothbore mean? The interior of the look smooth and there is a slide that goes up and down inside instead of flaps? Also, the engine is stock. If they are the stock 26 carbs are they worth using of would I be better off finding a different carb set-up? Thanks

I suggest you purchase a factory service manual or Clymers and perform all tune up steps in the order indicated before getting too excited about ripping into the carburetors. The 77 KZ1000 carbs are VM26 and are fairly adaptable and not likely the cause of your fouled plugs. Once you have performed a full tune up, check the voltage supplied to your coils as well and read our tech article on our website (see my sig) on coil repowering. Once you have tuned the bike and made sure the coils are getting 12VDC, and the plugs continue to foul, ask again about what to do with the carburetors.

hello ! i need help with my carb vm 26 (no pump ) on kawasaki kz 1000 1977, ref if r6 r 66 , i control every thing: timing , coil power, valve leak , adjustment , compression (150 145 145, 150) etc. they were good , needle is 5cn8 , clipped a 3 and jet are 2,0 and 120 , but i run emgo air pod and kz 900 exhaust (4 in 4) with baflle) , it is always to rich some poping and back fire other wise it's working well ( i want lower as a 1/2 turn on pilot screw )
am i correct or should i rejet smallest with the 4 in 4 exhaust ?
thank if you can help !

perrineric wrote: hello ! i need help with my carb vm 26 (no pump ) on kawasaki kz 1000 1977, ref if r6 r 66 , i control every thing: timing , coil power, valve leak , adjustment , compression (150 145 145, 150) etc. they were good , needle is 5cn8 , clipped a 3 and jet are 2,0 and 120 , but i run emgo air pod and kz 900 exhaust (4 in 4) with baflle) , it is always to rich some poping and back fire other wise it's working well ( i want lower as a 1/2 turn on pilot screw )
am i correct or should i rejet smallest with the 4 in 4 exhaust ?
thank if you can help !

FSM says stock sizes are:
Main 107.5, Needle Jet O-6, Jet Needle 5CN8 @ #3 clip, Pilot Jet 17.5, Cutaway 1.5, Fuel Level 3.0 ± 1 mm, Pilot Screws 1¼ ± ⅛ turn out.

Would first perform clear tube test on each carb to assure fuel levels are within spec.

And check valve clearances, as insufficient clearance can cause popping and backfire.

A too large main jet usually produces over-richness only at wot, which can be diagnosed via high speed throttle chop testing.

Good Fortune!