Extremely High Idle

Hallo everyone !! I'm new to this forum and I'm not a native English speaker -- please excuse my mistakes.

My sitauation seems to be really tricky. I'm becoming frustrated and that's why I'm trying to find some advice among you guys.
I own a KZ 550 B 1982, I bought the bike in a pretty beat up condition with a plan to build a cafe racer out of it. When I bought the bike the engine was running doubtfully - misfireings, lack of power.

Just a remark - parts for old Kawasaki's are really hard to get here in the Czech Republic - anyway here's my story.

I completely rebuild the carbs - ultrasonic cleaning, changed o-rings - regular stuff. The ignition centrifugal thingy on the right side of the engine was rusted - swapped it and the points from a second kz 550 engine I bought. Oil is Fully Synthetic 10w50. The intake is open right now - no pods no nothing. The only modification to the previous condition is an open exhaust muffler 4 to 1.

When I start the engine the rpm immidiately jump to 7000 and rise -- with or without choke. My first thought was an air leak -- changed the boots and basically glued them to the carb. I tried all possible positions of the pilot circuit screws. Needles are in the second highest groove. Throttle sliders completely down for sure. Stock jets, float level unknown (haven't checked yet) but it doesnt overflow. Measured the preasure in cylinders, all vacuum hoses are new and connected.

Had a theory that gas leaked into the oil - drained it today - texture and costistency seem fine to me.
Sprayed the whole engine and carb with soapy water - looking for air leaks. NOTHING.

What could it possibly be ?!! Could it be the muffler, or the oil or some ignition problem?
I'm really hopeless - I have rebuilt the carbs like 15 times now and the conditon is getting worse and worse

Thanks a milion for any advice.

Frenkie S22 wrote: . . . Throttle sliders completely down for sure. . . .

Bench sync may have failed to leave enough threads on the idle adjust screw to further lower the slides.

The slides must often be lowered further than the bench sync setting by using the idle adjust screw.

Good Fortune!

- here is even a video of the problem.

Dear Patton, thanks a lot for your answer - i'll check it out again. I tried the idle adjust screw all in, then either 1, 2 or 3 full turns out. Problem remains by each setting

Try loosening the throttle stop screw, it's located between carburetor #2 and #3.

When you re-assembled the carbs did you adjust the large idle control screw so it was centered? If not, you have no adjustment there. To correct this you can either take the carbs apart again and center it, OR you can simply lower each slide in each carb using the slide adjustment screws.

Also, you can not expect the engine to run properly without any air filter. The mixture will naturally be too lean. Install an air filter or if you cannot find a proper one install pod filters. Ed

Some pics will help you to locate the adjustment screws

Thank you everyone for the quick answers!

I'll try to answer the best way i can.
1. Big throttle stop screw is not even touching - I srewed it all the way out.

adjust the large idle control screw so it was centered

What do you mean by this exactly, please? Thank you.

2. I can visually see the sliders sitting all the way down.

3. Yes - I admit that I don't have any airfilter there - I tried it with pod filters even added some restrictors - No change. Anyway could it make such a big difference ? 7000 rpm ... The engine ran before without any airfilter.

4. I'll check the pulley position - haven't focused on that.

5. Each top adjustment small screw on the top is in the lowest position.

It seems still too much to me - freaking 7000 rpm out of nothing. Could the problem be just in the screw settings?
Couldn't it be sucking air thru somewhere else?

I tried to screw the pully all the way loose. The sliders did sink a little tiny bit. But it hasnt effected the problem. Start with choke still mega high revs. I know you'll tell me AIRLEAK! but I really checked it 5 times.

What about the float height could it be that?

I'm enclosing some pictures.

Frenkie S22 wrote: .................
1. Big throttle stop screw is not even touching - I screwed it all the way out.

adjust the large idle control screw so it was centered

What do you mean by this exactly, please? Thank you.
..........

The big throttle screw is suppose to allow you to adjust the idle. It does this by raising or lowering all slides the same amount when you turn it. The fact that screwing the big throttle stop screw all the way out does not lower the rpm is a sign that it was not centered when you assembled the carbs or when you did a bench sync.

You say you can see the slides are all the way down. Have you measured the opening of each slide using a .5 - 1.0 mm diameter wire rather than trying to eyeball it?

I highly recommend you try to lower the slides in each carb by using the adjustment on the top of each slide with the large throttle stop screw set in the centered position. Ed

It takes a very little amount of throttle to make the bike idle that high. The slides may look to be down all the way, but if they are up even 0.5mm the idle will be very high. Normal idle position is in the order of 0.1mm. 0.1mm will look like it's closed all the way, but it's not.

If it's jetted for pods, the pod filters will not make much difference.

The "idle control screw centered" does not really apply to these carbs. There is no key carb. All carbs are referenced from the main shaft.

The idle adjustment knob rotates the throttle shaft, but each throttle slide has its own adjustment (as others mentioned). If one adjustment is way off, it can cause the other 3 to stay open. You should probably pull the carbs and check the adjustments. If you want to "center" the adjustment range for each carb, you could, but that isn't really necessary as long none of them is far out from where it should be. How they are set from the factory is usually more than adequate to give each carb adjustability in both directions.

You probably should remove the throttle cables, or at least make sure the throttle cables are not stopping the throttle from closing.

There is a fast-idle adjustment that can also open the throttles a lot if the choke is activated. When the choke is off (lever down) the fast-idle mechanism is disabled.

Here is a website for the TK22 carbs.
s3.amazonaws.com/gpzweb/TK22mainPage/TK22mainPage.html

loudhvx wrote: It takes a very little amount of throttle to make the bike idle that high. The slides may look to be down all the way, but if they are up even 0.5mm the idle will be very high. Normal idle position is in the order of 0.1mm. 0.1mm will look like it's closed all the way, but it's not.

If it's jetted for pods, the pod filters will not make much difference.

The "idle control screw centered" does not really apply to these carbs. There is no key carb. All carbs are referenced from the main shaft.

The idle adjustment knob rotates the throttle shaft, but each throttle slide has its own adjustment (as others mentioned). If one adjustment is way off, it can cause the other 3 to stay open. You should probably pull the carbs and check the adjustments. If you want to "center" the adjustment range for each carb, you could, but that isn't really necessary as long none of them is far out from where it should be. How they are set from the factory is usually more than adequate to give each carb adjustability in both directions.

You probably should remove the throttle cables, or at least make sure the throttle cables are not stopping the throttle from closing.

There is a fast-idle adjustment that can also open the throttles a lot if the choke is activated. When the choke is off (lever down) the fast-idle mechanism is disabled.

Here is a website for the TK22 carbs.
s3.amazonaws.com/gpzweb/TK22mainPage/TK22mainPage.html

There is no “key carb” on my KZ650-C1 Mikuni VM24SS carbs either. Each carb has a screw above the slide that is used to adjust the height of the individual slide; for example when doing a bench sync. There also is a throttle stop screw with a large knob on it. That screw is used to adjust the idle speed since it affects how high or low all 4 slides rest when the throttle is released. If that throttle stop screw is turned all the way (or nearly all the way) out when the individual slide heights are adjusted it cannot lower the slides by turning it further out. It can raise the slides by turning it in, but of course that increases the idle rpm. I have read several threads by folks who do the bench sync with the throttle stop screw turned too far out, and then they cannot use it to lower the slides. The carbs on the bike in question may be somewhat different, and I may be wrong, but I would expect the throttle stop screw to operate the same way and have the same issue if the slide heights are adjusted with it turned too far out.

The four adjusters just need to be somewhere near the middle of their range so they have room to move in either direction for the final adjustment. Then they are adjusted so that each slide is near the same height. To do that, the idle knob can be set to any random position so long as all four slides are up by some amount. There is not a "centered" knob position requirement. Then the individual adjusters are set so all four slides are at the same height.

So it doesn't have to be "centered" but just open by some amount. When the knob is turned out, all four slides should close. If one slide is lower than the others, it will hold the others open. If its by a large amount, the motor will race.

To see the small differences, its best to do this off the bike so you can look into the carb outlets.

That is just the bench sync, and will be inadequate to be the final sync, compared to syncing based on equal vacuum. The adjusters are very sensitive.