Mikuni Carburetor Tuning

Hey guys, new user here.

Last year I bought a KZ440 LTD and put it in storage. I've recently began riding it and have noticed a couple things regarding the feeling of the engine at idle and under load. I tweaked with the idle screw and then eventually moved to tweaking the air screw but my problem still persists and I can't seem to find that "perfect spot". The previous owner installed a Mikuni carb connected with a manifold. I followed some instructions on youtube to tune the screws but I can't seem to notice much change in rpm when I adjust the air screw. I found the max rpm with the screw almost all the way out and feel this is definitely incorrect. Currently the engine idles poorly and the rpms seem to hop up and drop, eventually the engine stops after a puffing of air noise comes from the carb.

What do you guys think is going on? How should I correctly tune this carb?

Edit: So today there was some more drama with the motorcycle. I decided to add some oil since it's been dangerously low for a while. I ended up adding a bit too much and the engine backfired really hard and created a small leak in the exhaust (oops). I drained the oil and it seemed to be alright, but the same problem now persists.

I found out that there is actually air/fuel mixture shooting out the back of my carb into my air filter. With the choke on I can get the engine to start but it only lasts a few seconds before it dies or the carb shoots fuel out and then dies. It also occasionally backfires and theres some gross looking smoke (brown?) coming out of the left exhaust.

I cleaned the carb today and it seemed to be in perfect condition. Once thing I noticed though is that on the air filter side, the valve does not sit all the way on the base of the carb, unlike on the fuel side. It seems this way by design but I feel like it might have something to do with my problem? Could it be my carb is on backwards? It was running ok for the past couple weeks but now it's not working at all.

Colortune and vacuum sync will allow you to get the carbs on the nose if the carbs have been broken down and cleaned. Have you had them apart?
That also assumes there aren't other non-carb issues haunting you. Like a leak in the carb holders or ignition issues. I would only do tuning with a fresh set of spark plugs. If you have a digital volt meter (DVM) or can borrow one, check the plug wires resistance and the primary and secondary windings resistance on your coils to see if they are in spec.

I hear you mention you picked some tuning information off the web. for a 30+ year old bike, expect that you will be the mechanic and it sounds like you are game. Your best friend is a Kawasaki Service Manual. You'll get great support here, but you need the factory procedures and specs.

post a pic.


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