77 kz1000 #2 carb runs cooler than the others

I've just got my 77 kz1000 that I bought in the fall ready to ride.

100% stock including original pipes and air box
135 psi +or- all across
new plugs, points, condensers, timing/spark all good
professionally cleaned tank, in line fuel filters
cleaned and reassembled carbs as best I could
starts well

After warm up at idle the #2 exhaust pipe is slightly colder than the others. Not cold by any means. When I spray the pipes with water, the water vaporizes instantly with no hiss on #1,3,&4. On #2 the water vaporizes instantly as well, but with a slight hiss.

It doesn't want to idle at less than 1100 rpm. There is a noticeable miss up to 4000 rpm when riding.

My question is; At what point does the pilot system get over ridden by the main jet system? Is it likely that I still have some guck in the #2 pilot system? Or is it likely something else?

OK, that's 3 questions. Thanks in advance.

Replaced the sparkplug caps too? They can fail making for a situation like this. Checked the input voltage to the ignition coils? It should be almost the same as battery voltage.

The ignition coils when new were marginal, and with heat,vibration and age can start to break down.

www.z1enterprises.com sells a replacement set of coils along with the 3 ohm green Dyna coils.

Another brand is Accel, who makes a good set of replacement ignition coils.

Good points. No pun intended. As a check, before I start ordering parts, I'll try switching plug wires/coils around and see if the problem follows the wire. Or I could try the coils/wires from my 900 which I know are good.

I still would like to know at what point, rpm-wise, when the main jet takes over from the pilot system.

Sounds like you need to sync your carbs. This is done with the bike running and up to temp. There are threads on how to make a inexpensive sync tool, also which of the Pro tools are the best including info on the Color Tune setup. Always be sure you don't have vacuum leaks at the intake manifolds, any of the hoses hooked to the nipples on the manifolds. When cleaning the carbs, did you set the float level? Which method, "Clear Tube",, or measured height? Most here will tell you only the Clear tube method will be accurate.
Pilot jet @ Idle slowly tapering off up the throttle opening, overlapping the next circuit of the needle jet and jet needle, then main jet @ 3/4 throttle up. There is alot of carb tuning info on site including some pdf files of Mikuni carbs, and tuning them.
If the search function here doesn't return the results, use Google with KZR in the text.

Galactica wrote:

Good points. No pun intended. As a check, before I start ordering parts, I'll try switching plug wires/coils around and see if the problem follows the wire. Or I could try the coils/wires from my 900 which I know are good.

If you switch coils/plug wires around and the problem doesn't transfer, check the plug even if it's new, I spent better part of a day knowing with certainty it wasn't the plug because I had just bought them and gapped them, spent lots of time looking at everything but the new plugs, turned out the cylinder was off due to a bad, brand-new NGK plug.

Sounds like this bike was a 'revival' from not running for awhile, I bought a '77 kz1000-A1 brand new in '77 when I was 17, it was my 2nd bike. If you checked your valve clearances as part of the revival were they in spec? If the bike has any mileage on her you should probably check valve clearances as part of the revival, not saying thats the cause but putting the valve clearances right eliminates one contributing factor to poor running/starting.

ALSO: since this was a revival -- if you used the battery that came with the bike -- know this. Each cell in a bike battery puts out 2.1 volts dc. An 'off' battery will cause a misfire often enough on a bike.

Fill with distilled water, then charge it. Wait a couple hours *after* the charger was removed (because the voltage reading will be high immediately after you remove the charger, and after 1 to 2 hours will drop down to a steady-state level so the initial reading you see on the battery just after the charger's removed will be too high -- easy to verify that if you've always checked the voltage right after the charger).

You really need to see a steady-state level of (2.1vdc) x 6 cells = 12.6vdc. If you see 12.55 to 12.65vdc *after* 2 hours, the battery is fully charged.

If the engine is missing then pull your battery. Check the voltage. If it is below 12.55vdc by a wide margin, use the info above to fully charge her (charge/wait 2 hours/check). Each cell puts out 2.1vdc when fully charged. If its not fully charged then the plugs won't get consistently good spark to burn the fuel and you can get a miss.

Galactica wrote:

...still would like to know at what point, rpm-wise, when the main jet takes over from the pilot system.

Transitions Pilot > jet needle and needle-jet > main-jet
are dependent on throttle position (not so much on RPM).

Good Fortune!

Thanks for all the suggestions so far. I believe I've already addressed most of them. Yes, the bike is a revival.

New battery, and checked the voltage from the regulator. OK.
Have switched spark plugs to check for a bad one. Same result.
Performed clear tube float level adjustment.
Synched carbs. Will re-check while I have the tank off today.

One thing I have not done is to check the valve shim gap. I'm assuming that since the compression readings are almost identical that the shims are OK. I'll do everything else before I pull the valve cover. Do the easiest and least messy stuff first, right? Plus I don't have a spare gasket and my local Kawasaki dealer is closed until the 4th of January.

I'm heading out to the garage now to check the coil/wire to #2 and I'll re check the carb synch.

I'm the second owner of this bike and I believe the engine to be in excellent shape. There is absolutely no smoke coming from the exhaust pipes, not even on start-up, and it smells OK too.

This afternoon I swapped out the #2/3 coil/wires with the one from my 900 that I know is good. While I had the tank off to do that I installed my alternate fuel source and carb synch gauge. Warmed it up, synch is good. Same result with the known good coil. That is, a slightly cooler #2 exhaust and low rpm miss.

Then I re-installed the original coil, rinsed out the tank before re-installing it,and put new gas with 1/2 can of Sea Foam. After a while it seemed to run better, with only an intermittent miss. So either I have an intermittent electrical miss, or the new gas and Sea Foam are cleaning out the carb.

I'll keep ya posted. Man, I love this bike!!

My experience says is an air leak from what you describe.

Bike misses until after 4000rpm / or full advance.
#2 cylinder is cooler than others when @ idle, but still gets warm when under load - thus firing.

There is an air leak on the intake side of the carb.
When you balance the carbs, you are actually closing the slide/butterfly because an air leak shows up as a vacuum drop on a manometer, and thus closing the slide/butterfly brings up the vacuum to match the reading of the other cylinders, and the bike is practically running on 3 cylinders. Throttle it and the pipe gets hot, drop to idle and she stops firing.
and YES the engine can sound and idle fine on 3 cyls.

Seen this many times!

Pull the carbs and the engine to carb holders/boots. Use Permatex Motoseal (gas proof) to seal the carb holders to the engine. Visually inspect the carb throttle bodies and make sure the gap of the slide/butterflys all look the same! Dont perform a sync until all firing cylinder problems/header temps are resolved, and idle the bike at 1500rpm for now.

Taper the end of the little straw from a can of spray carb cleaner with a knife, then shove it into the pilot jet. Spray cleaner thru, and visually verify that the spray is coming through all the idle mixture holes and into the bore of that carb, same as the others.

Use a thin film of grease in the carb holders then install carbs.

Fire up bike and problem should be gone - if not, then adjust the mixture screw to add more fuel some and see if it helps - it will.

Best of luck!

Galactica wrote:

...One thing I have not done is to check the valve shim gap. I'm assuming that since the compression readings are almost identical that the shims are OK....

Satisfactory cold compression readings do NOT mean the valve clearances are to specs.

Too tight gaps may allow perfect cold compression, and begin leaking compression as the running engine warms.

Good Fortune!

Pilot circuit being not perfectly clean could be causing the reported condition.

Good Fortune!