1980 kz440B running on one cylinder

Hi Folks,

I have been struggling to get my bike running on two cylinders.  I cleaned and rebuilt the carbs many times.  I tried syncing the carbs.  I changed rubber booths, I adjusted the valves, checked timing still no luck.  I can get the left cylinder running most of the time.  However, I was able to get the right cylinder running at which point the left one stopped running.  I can change which cylinder runs by adjusting the carb sync screw.  After bench syncing the left cylinder runs but if I open up the right carb then the right cylinder fires while left cylinder stops.  I can get the bike to idle with the left cylinder running by itself albeit at over 2k rpm.  I can get both cylinders going over 4k rpm intermittently.  
I get good compression from both cylinders. I cannot pinpoint if the issue is carb or ignition. The bike is completely stock and only has 11k miles. Any suggestion is appreciated.

Are you sure your ignition advancer to point cam is align correct?
The cam lobe can be easy installed 180 degree off ignition timing after a rebuild.

 
 
 

I will check the timing again but I really did not change it from the time when the bike was running.  I did adjust the gap just a little.  
I always had a cold starting problem.  The spring that holds the choke on one side of the carb is a little warn so I have to manually reach and hold it from behind to help start when cold.  
One other detail, when I cross the plug wires the cylinder that is not running does not change thus I thought issue could not be timing. or ignition.
As I said before I can open up the right cylinder butterfly (using the sync screw in the middle) at which point that cylinder will start running but then the left side cylinder stops running.  

 

You should read the post about your KZ440 carb sync adjustment mechanism.
It´s a common error on re-assembly both carbs linkages together....

kzrider.com/forum/3-carburetor/616638-ex...y-high-rpms-on-start

I have gone thru the carbs and sync mechanism multiple times.  I bench sync'd them, used the vacuum ports and did a sync with a in-house contraption I made looking at youtube videos. I will check the sync mechanism again just to make sure I am not missing anything.  I am wondering if throwing out the CV carbs and getting VM30's would make my life easier but I am not sure if the issue is carbs or ignition.  BTW for the choke mechanism, the spring that is supposed to keep to two intake sides in sync is all worn out. I looked around and could not find a replacement part, does any one have a solution for this? The right side intake just flops around due to the weak spring unless I hold it by hand from the back of the carbs.  when I am cranking.  
Thanks for the suggestions.

I have a 81 kz440 and it has a dead cylinder, its geting fuel as far as I can tell becuse the pluck is just alittle wet not much.
I change the spark plug. the spark is a redish orange color with a dot
of blue. I even made sure the gap was correct on the spark plug.
 

wrote:

I have gone thru the carbs and sync mechanism multiple times.  I bench sync'd them, used the vacuum ports and did a sync with a in-house contraption I made looking at youtube videos. I will check the sync mechanism again just to make sure I am not missing anything.  I am wondering if throwing out the CV carbs and getting VM30's would make my life easier but I am not sure if the issue is carbs or ignition.  BTW for the choke mechanism, the spring that is supposed to keep to two intake sides in sync is all worn out. I looked around and could not find a replacement part, does any one have a solution for this? The right side intake just flops around due to the weak spring unless I hold it by hand from the back of the carbs.  when I am cranking.  
Thanks for the suggestions.

I am 99% sure the choke plates are connected mechanically, not with a spring. If one is flopping around, then something is broken or missing or assembled incorrectly.
Looks like all but one of the springs are still available new.
www.partzilla.com/catalog/kawasaki/motor...arburetor-assy-80-b1

When I said spring I was referring to the yellow circled mechanism, you can see a wound-up spring there.  In my case this is pretty loose and the right side choke plate is not held tightly.  I can hear it flapping when I hit the start button.  I can put my finger on the back of this spring and bike fires up easier.  
BTW I still have the 1 cylinder running only issue.  I can actually adjust the sync screw and change which cylinder runs.  I removed the carbs and am doing more cleaning. I think the issue is still the idle circuit in the carbs.
- When choke is on and bike is fast idling if I take off the right plug wire the idle goes down (when left cylinder is only running and eventually dies),
- When I take off the left plug wire the right cylinder can continue running (in fast idle)
- looks like the left cylinder is actually not in fast idle.  Basically I expect with choke rpms above 2k range but left cylinder cannot idle up high.  Also I can hear hicup thru the left carb which suggests it is starving for fuel)
- iIf I open up the rigth side cylinder enough the left one just cannot keep up so only right side runs.  If I close the throttle on the right side (using the sync screw) the right side will not idle.  
I am going to try 2 things:

1- Clean the carbs once more
2- increase the float so more fuel is on the left cylinder

If these do not work I am going to toss these carbs out and get some VM carbs and put them on.