Why is it that almost every four pot Jap bike I've ever owned needs the carbs stripping after a winter
layup ?

This year my ZX9r (bought last summer) is no different.
Couple of weeks ago went to start it and as per usual fuel leaked out the overflows
so take them off to clean the float valves and everything else. Didn't separate the bodies though.
Airways cleaned with brake cleaner followed by airline jets, emulsion tubes etc went in the ultrasonic
bath. All diaphragm were fine so reassembled.

Now the b&st&rd won't run.

Full choke and after a couple of seconds it catches, revs its tits off then dies, anything less than full
choke it won't even try to start. I can see fuel is coming out the jets as it's cranked though.
Spray a mist of petrol into the airbox and it runs.

I've obviously done something fundamentally wrong when reassembling but have stripped them again
and buggered if I can see what. New plugs haven't helped and it is fresh petrol.

Air leaking in somewhere it shouldnt? After the butterflies?

Check diagrams are seated right.
Check orings that go between bodies.
Check boots arent split.
Spray easy start around carbs to try and pin point pos air leak - revs will rise if there is.

by any chance did you accidentally lose the little tiny tiny baby vacuum o rings that sit between the diaphragm and the top covers?

All diaphragms and O rings had a thin smear of red rubber grease to hold them in place during
installation as I've had issues on other bikes. Usually when the rings have shrunk slightly with
age.
Ash, the diaphragms don't have the tiny oring, the rubber is moulded to have a lug sticking out
which has a tiny brass sleeve with a micro hole in. All present and clear, I made sure not to grease
the lug. 1999 ZX9r C model.

Never had probs after stripping any other sets of carbs

It sounds more like your pump is not working.

pump would be my next check

and measure float levels.
Also, had something similar when my fuel pump relay packed in.

Float levels were set correctly, although I haven't checked the fuel level but surely one is
a product of the other ?
Fuel pump is definately working, i have a funnel set up as a makeshift fueltank and can
see the level dropping and if I hold the pump whilst cranking can feel the pulses.
I also powered it up at the relay in order to make sure the float valves were sealing.

Today I again checked the drillings I can get at, diaphragms and jets, all seem clear, carb mounting rubbers
are in good condition and pliable and the airway in the diaphram as pictured by Ash is clear.
Using my palm I blocked each port and cranked the motor, engine definately sucking on the
induction stroke, same when I fitted the carbs.

One thing I have now noticed is the slides do not move when the engine is cranking, I'm sure
they usually flutter whilst cranking and move properly when revving. So I'm thinking there's
an airway that's blocked somewhere. Suppose it's possible I've wedged some crap into a tiny
drilling with the blow gun.

[Edited on 12/4/12 by NigeEss]