1981 KZ440 idling/running/choke problem.

This bike has been non-runnig for some time now. It will run and idle, but only fires on the right bank. I have replaced the plugs, checked the valves, cleaned the carbs, checked compression (165lbs each), checked for adequite spark and everything seemed ok. The airbox is not currently installed and the idle/air mixture screw on one side (has been switched back and fourth with no change) has the tip broken off. It will run when you play with idle, but it never seems to be happy in just one place. you need to keep playing with it. there is a popping sound from the exhaust also. the right side header was about 600 degrees and the left was about 270 when it ran for about 15 minutes. It will sometimes surge up and down then stall... above idle, it seems to be running on bith cylinders...


HELP!!!!

The end of the mixture screw is a needle tip. It is broken off in the hole where it seats. Get the broken tip out and replace the bad mixture screw. The carb kit for a 440 contains the mixture screw, a float needle and the bowl oring and couple other orings. Invest in a couple carb kits.

the mixture screw breaking off did not affect the way it ran at all. I have since replaced the screw and it still runs exactly the same.

Did you remove the broken tip? An idle circuit issue seems to be being described in your initial post. If the mixture screw isn't the issue, then you should likely clean the internal passageways associated with the pilot circuit, adjust the fuel level in the bowls and balance the carburetors (sync).

the broken tip was cleaned. the pilot ciscuit is cleaned. the pilot jets were both clogged, but I replaced them both. I have since installed an air box and now it revs up to 3000 rpms and will not back down...

You HAVE to have the airbox installed and installed correctly to get them to idle and run properly. I have an 81 kz440ltd and I had problems until I got a factory airbox and used that.

Have correct ignition timing and proper operation of advancer been verified with a strobe type timing light?

Was thumb idle screw set in proper position and carbs bench synced per FSM procedure before reassembly?

Has running engine been checked for air leaks at carb holders and vacuum caps?

Good Luck!

how do you check timing on these?

low93bowtie wrote:

...have since installed an air box and now it revs up to 3000 rpms and will not back down...

As posted by EasyRider1 -- You HAVE to have the airbox installed and installed correctly to get them to idle and run properly. I have an 81 kz440ltd and I had problems until I got a factory airbox and used that.

The following might also be helpful, courtesy of The Gringo from an earlier thread:

This won't help you with your current problem of not starting but once you do get her running you'll need to make sure you have your air filter installed correctly. This might sound crazy but on the 440 LTD it is imperative or your bike is gonna run like crap. There was someone here a few weeks back and we had him checking all sorts of things and it turned out to be the air filter installation.

On your bike open the seat and grab the rear of the filter and try lifting it up, if it moves your filter is on wrong. There is a slot for lack of a better term on the airbox and the filter has to slide into that first before you install the two screws on the top. I'm just trying to save you from some future headaches.

Good Luck!