TOPIC:

Subtle "popping" typically indicates one or more of the Main-Idle ports is partially blocked - creating a "too lean" mixture. The "Cleaning Tool" I make is a very affective method of flushing out all of the fuel/air circuits.
While you've got the carbs on the bench, remove the idle jets and inspect each one under magnification. If these jets are "originals" I strongly recommend they be replaced as they can mimic a similar situation.
Degraded idle-jets have probably driven some to a point of insanity, trying to figure this out. It did for me until I put a set of 6 originals under a microscope.
Too be clear: If these jets are anything but 'Perfect" - they are garbage - can't be "repaired" - don't waste your time !
www.kz1300.com/index.php/forum/carburato...vs-old?start=6#20926

Hi Met,

Agree with Scotch on the idle jets. Changed mine for new ones and it made a big difference.

Regards

Martin.

took the bike out again today....
that popping is pronounced at deceleration....but also at idle.

it never affects the performance and the power is always there at the twist of the grip.
it starts and idles rough, sometimes backfiring...
all that goes when i up the throtle.
Gunstons Colortune showed a blue flame in all six cylinders...
it has had a carbie overhaul with all jets and diagrams changed....

i was thinking of one other thing....
can anyone tell me what is this contraption pictured....
i think an air valve of some type.....anti pollution stuff....?
i noticed that this is NOT on my bike...
and it might be very well the reason....???
not sure....

That's the vacuum switch valve between the air filter box and the air injection valves in the camshaft cover. The small hoses attach to the intake manifold at the ports that you would use to sync the carbs.
Page 181 of the manual describes the operation of this valve and not having it in place would completely explain why you have backfiring in the exhaust pipe. You have uncontrolled air injection .

that is one good thing - mystery solved and it maybe the cause of all my problems....just got to look and find one of these valves now.
on my bike i have two dome nuts sealing off the vents at the top case and another one sealing of the hole in the air cleaner.....
i cant see however anywhere on my bike where the two smaller left and right hoses would go.....these look to be from the photo, about 4mm in diameter and smaller than the other hoses...

Something to take into account on this subject...............

The UK / European Z1300 Model does NOT have the Vacuum System fitted, and does not have any running issues with it and cylinder head is the same.

On all the US KZ1300 Models I have owned in the past (7 + ), I have removed the system and sealed up the head plates and hole in the airbox.........never ever had any form of problems.

I have also owned six ZRX1200's including the one I have now and they all come with the Vacuum Device fitted............and everyone in the UK Owners Club removes them an seals them up.........no problems !

I honestly cannot see this is the cause of your problem, so would look elsewhere if I were you and leave the Vacuum Device off..........as its less to go wrong !

Pete F
UK (or whats left of it).