hesitation off idle

I did adjust the pilot screws this afternoon. They were a touch on the lean side, but not bad. I am planning on pulling off the carbs next to change out the main jets. I have been told to not adjust too much on main jets, so should I go up 1 or 2 sizes for my aftermarket header? No popping on deceleration, but it does pop once or twice right at first acceleration (cold).

I suggest 2 sizes for a pipe, then do a plug chop to verify correct color of the plugs.

megadub72 wrote: ... am planning on pulling off the carbs next to change out the main jets....

Re-sizing the main jets might or might not improve carb performance in the WOT (wide open throttle) range, but won't influence the "hesitation off idle."
But with carbs removed, the pilot circuits may be cleaned, which will likely reduce and perhaps eliminate the hesitation off idle.

Here's one cleaning method to consider:



Note that the pilot adjustment screws in the above diagram are side-located, as in this example:




If carbs have bottom-located pilot screws (instead of side-located pilot screws), the above procedure may be adapted to accomplish the same objective of assuring clear mixture passage into the carb bore.



A proper bench sync should also be performed, being sure to have the throttle screw set in about its middle position before adjusting the slide heights. Which is to enable further lowering when performing the final sync with engine running.

Good Fortune!

koolaid_kid wrote: Not sure what folk on this forum use, but on another forum the Morgan Carbtune is considered the gold standard. It's a one-time investment, and well worth it iMHO.

That is the one I bought to do this bike with. I had one before that I used on my last KZ900. I should have kept it, but sold it after I sold the bike. I am keeping this one this time.

Great instructions. I will definitely do that while I have the carbs off. Thanks for the diagram.

If it ran ok before use some Berrymans B12 carb cleaner. One half bottle per tank.
Is a fuel filter being used?

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megadub72 wrote: When I sit at a light, it idles just fine. When I get ready to go from the light, if I just go straight to throttle, it will die. If I tap the throttle first, then takeoff there is no problem. It is apparently a weak point, but I do not know if it is a needle position or a pilot jet problem. Has anyone dealt with this hesitation off idle? How did you fix it?

Check needle clip position.

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I am going to pull the carbs and check the main jet sizes, so I will clean them thoroughly then. Yes, there is a filter. How often do you recommend carb cleaner in the fuel?

I do not know much about needle clip position, but should I wait to check those until after I see if a larger jet fixes the problem? Like change only one thing at a time?

Thanks for the help.

Everyone jumps to the carbs first when there is a problem, and to be fair they are probably usually the problem....but....the Kawasaki manual says to check a whole list of things before messing with the carbs.

Pg. 18 in mine...

Preliminary Checks :

Engine Oil
Spark Plugs
Ignition Timing
Throttle Cables
Cylinder Compression
Air Cleaner Element
Air Cleaner Duct and Carb Holder Leak (just replace them, well worth it)
Camshaft Chain
Valve Clearances

I think it should also list the Advancer, and check the voltage to you coils. Do a search and you will find LOTS of info on voltage drop to the coils. If you do have a voltage drop the relay mod works but I recommend you actually find and fix the problem instead of just avoiding it.

My bike didn't finally start running really well until I did EVERYTHING....each individual thing helped some, but when I finally got everything correct, it all came together and it runs very well now.

What kind of manual do you have? You need the real deal Kawasaki one, forget the others. Don't ignore any of the listed items, I ignored the throttle cable adjustment because I knew it was correct. Well, it was just about the last thing I did and it made a difference.....coming off idle....just like the problem you are describing.

If the hesitation is in the midrange, raise the needle one spot.
That is placing the e-clip in the next grove down as it sits in
the carb.

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I have cleaned the carbs, and I blew through all the passages to assure no blockages. It all appears clean and working. I was wondering if anyone knows what size of main jets are supposed to be in KZ1000ST Mikuni carbs? I thought it may be running a bit lean, because someone added an aftermarket header, but I checked one of the plugs and it is really black. I just came off a pretty long ride, so I wouldn't suspect any false readings.

I just can't seem to find what size the jets are supposed to be anywhere on the internet. I can't find it in my "Kawasaki Heavy Industries" service manual either. Help!

I've got a chart that shows the 1979 Standard Model used a 102.5 main (110 shaft) and 15 pilot. Do you have VM28SS carbs?

Hopefully someone else will confirm these jet sizes.