I just got ninja 1991 zx600c with 5500 mi. bike had been sitting for a while,didnt run!Removed and cleaned carbs several times,ran pin
guages thru jets to make shure they were opened to size,o-rings around pilot screws were missing,bought new,the vacuum diaphrams look good.seems like all the parts are there! The bike Idles and revs great sitting still, but when I get it on the road and put a load on it
it falls flat on its face at around 2000 rpm, a shot of choke brings it back to life! NEED INPUT!!!!

 

How many jets did you clean? Are th e vaccume hoses all connected?

 

I cleaned 4 idle jets and all 4 main jets ,according to the vacuum diagram under the seat #1&4 carb vacuume go to an egr valve,#2goes to the fuel petock and #3 I capped.I tried running with egr capped but no change !
It just seems like its starving for fuel.Is there a possibility the diaphrams are leaking is there another way to check other than visual?
Like I said before Idles and revs greatsitting still. main jets .041 dia, idle jets .014 dia.

 

I suspect an ignition problem. I am not familiar with that model, but if it uses a single coil, or a paired coil it could cause more than one cylinder to quit under load.

Two easy things to do to get a handle on the problem.

With a spray bottle of a soap and water mix, mist the wires, and coils till they are wet. Then try a free rev and listen. I bet it dies or chokes without even being on the road (meaning you have a secondary ignition problem). I’ll bet the wires dry rotted from sitting.

Second is to get in a location where you can reproduce the problem and coast safely to a work area. Reproduce the problem for 10 seconds or so if possible. Shut it off while it is doing it and coast to the work area and pull the plugs. Wet ones mean wayyyy too much fuel or an ignition problem.

Please post your findings.