I need help!!! I'm stumped.

[SAINT777]

Howzit guys. So here is my story - I bought fazer 400 97 model +- 7 years ago. I lost faith in the bike when it would randomly die riding home sometimes from work. So I threw a plastic cover over it and put it rest... 7 years later, ive I got the heart to revive it..I've cleaned  the fuel tank, cleaned the carb and bench synced the carb aswell...I've bought and put new the 600 manifold boots on because the others were toast. Changed the oil and changed the oil filter.So heres the juice, ive got it to fire on all cyclinders and it idles for a bit and then died and won't fire and run again until the stars align.. Im also having a backfire through the carb theough to air filter boxer once in a while.. I just don't know what could be causing this issue..Is it fuel starvation or is an air seal issue thats causing a bubble thats not allowing fuel through...PS ive made a rig up for fuel, from a bottle so i dont have to rely on the pet cock volve and fuel tank while i work on the bike. 
Im losing hope Let me add the previous owner has removed the choke "plate". Have no idea why but ya i cant use the choke unless i manually pull on the brass bars on the carb.. S.O.S

[Gnasher]

Sounds like a fuelling issue as it's starting then dying and slowly refilling hence it will restart after a period of time.

Possiably sticking float/s, blocking/blocked metering valves, pilot jet/s, air bleed holes.  Could also be stuck open/closed enricher (choke) plungers, running way too too lean or too rich is there a heavy fuel smell plugs wet?  This would be combination of all the above what happens if when it's idling you open the throttle? 

Bench balancing well that's never really a plan and won't be helping.  Although it shouldn't stop it restarting and that is suggesting fuel starvation.  Remove the carbs and recheck your work, you only need the slightest bit of crud or blocked air bleed, worn metering valve, incorrectly fitted jet, etc etc. 

Probably wouldn't be a bad idea to check all the ignition circuit connections either but as it is starting just not running I don't think your issue is there.

[BBROWN1664]

On the 600, if the fuel tank breather pipes get kinked, after a few miles you get a vacuum in the tank preventing fuel getting to teh carbs. May be worth checking the breatehr pipes.

[Gnasher]

On the 600, if the fuel tank breather pipes get kinked, after a few miles you get a vacuum in the tank preventing fuel getting to teh carbs. May be worth checking the breatehr pipes.

Yep could well be as simple as the above.

[unfazed]

What you say sounds like fuel starvation. The biggest difference in the 400 and the 600 is that they do not have a fuel pump. Unlike the 600 the 400 has a very small inline fuel filter and a vacuum fuel tap These filters should be changed more often that the large one in the 600. It would be a good idea to change this first especially if the bike has been idle for a long time with fuel in the line. The vacuum pipe from the fuel tap goes hard and cracks or perishes and would also need to be checked. The OEM part number for the filter is 4YR-24560-00. I am sure there are inline filters available that would fit, but be sure they are good quality.

If this does not help then remove the carbs again and check the pilot jets are clear. not easiy to clean and sometime need to be soak in cellulose thinners for a few hours to dislodge the petrol laquer. If you had the carbs apart and had the main jet and the tube is screws in to, you need to check if the nozzle that fits in above the holder is still there. these do not always come easily out but can fall out

May be worthwhile sourcing a spare set of Kehin CVK CV carbs for spares, Some older small Kawasakis fours had Kehin CVK CVcarbs if you cannot get the Fazer ones