Idle erratic and lean on one side rich on the othe

Hello, I have a '79 Kawasaki KZ400 LTD. 2-1 Kerker exhaust. Everything is stock on this bike.

Here are the symptoms:

The bike was in storage and properly stored for about 2 years.
Runs best with choke on (not fully). Left cylinder is running lean right cylinder is rich.
Bike can idle around 600rpm but after running for a while it heats the bike up and the idle is more erattic.
When RPMs are below 3000RPM in 1st the bike tends to lope along until I get to around 3500 rpm then it kicks
in and we take off.

My feeling is that the carbs are synced pretty closely but that I am picking up off the intermediate jet versus
the pilot jet on the right carb. I have gone back 3 times and cleaned the pilot jets, so I cleaned the petcock
now I plan on replacing the fuel lines and getting a jet kit.

My friend and I are both stuck on this. I believe I need to pull the carbs, tear them down and let'em soak.

Feedback is greatly appreciated, thanks in advance.


1. Carbs have been checked for vacuum leaks

2. Fuel petcock cleaned, tank inside is very clean

3. Fuel filter installed

4. Oil and filter has been changed

5. valve clearance checked and adjusted accordinly

6. Bike idles but as it heats up it starts to drop the idle, the idle screw tends to make "WIDE" adjustments

7 Bike can idle around 600rpm but after running for a while it heats the bike up and the idle is more iradic.

From High idle RPM to dead.

8. Brake service done

9. New clutch cable

10. Needles cleaned and increased slightly in size

11. adjusted idle screws on side of carbs (think thats the wrong terminology)

If bike only runs on choke then some jetss are still blocked.
Soaking carbs is rarely enough. I would suggest remove all the jets and poke every tiny hole you can find with a nylon bristle or heavy fishing line or if bad try a 1st guitar string and then blow everything out well with compressed air. Check diaphragms (if your carbs have them) for pin holes and make sure the fuel level in the float bowls is set to where it should be. Search "clear tube method" here.
You can find a manual at kz400.com if you need one.
Good luck

JR wrote: If bike only runs on choke then some jetss are still blocked.
Soaking carbs is rarely enough. I would suggest remove all the jets and poke every tiny hole you can find with a nylon bristle or heavy fishing line or if bad try a 1st guitar string and then blow everything out well with compressed air. Check diaphragms (if your carbs have them) for pin holes and make sure the fuel level in the float bowls is set to where it should be. Search "clear tube method" here.
You can find a manual at kz400.com if you need one.
Good luck

Guitar string are a fantasic way of poking blockages through the jets and other hard to reach places. Strings are usually made from nickel, and are sturdy, but soft enough, to not cause any damage to your passages.

If you don't have the 1st string (the high E) available, go to your local music shop, and request a 10 guage Earnie Ball string. Some strings (such as Elixers) are coated with a polyurethane that can chip off of the string, and potentially clog the carbs later on. Make sure you DO NOT try to clean passages with a WOUND string. As these can potentially do terrible harm to your carbs.

Strings typically run $1 a piece. I would get a few, as they do rust over time.

Ok guys! Thanks very much for the feed back. I will do a complete tear down on the carbs. I have the original shop manual I was trying to avoid a full tear down but it sounds like that will probably be the remedy. Also thanks for the good idea on the guitar strings never knew about that.

also when running bike without riding it.
you must use a fan on it or it will over heat!
and also your pilots are blocked still

Well, since we last talked I have done many things, including that which was suggested I feel that I have the wrong jets in the bike now, not only feel but I am pretty sure.

The bike has the stock Kz400 H1 LTD setup for jets:

35 PILOT
70 PRIMARY
80 SECONDARY

With that said it does not have the original exhaust that this jetting setup was meant for, I have the Kerker by Kawasaki 2-1 exhaust which I believe is the reason I am lean.

Currently my pilot screw is turned out 1.5 turns from closed. Which my understanding is the minimum I should be at it is also the minimum the bike runs at.

I planned to go to this setup on my jet sizes. (i really am guessing on sizes I should use)

PILOT: 42
PRIMARY 85
SECONDARY 75