Hi,
Have a look at:
http://www.geocities.com/largeinnit/Bike/carb1.jpg
The smaller pipe on left I've labelled as reserve, but this may be vacuum. It's just that it's attached to the reserve setting on the petcock and thus I made my deduction. It's a 98 Kawasaki gpz 500s. I don't think there is a problem with the petrol as when I fill the reserve/vacuum pipe with petrol using a small 500ml bottle as a feed the bike starts, but when I try this with main feed it doesn't. I've tried using the main feed with tank on and off - but no luck in either case.
The fuel pipes look ok, I've taken them off blown air thru and ran petrol cleaner thru as well. At the moment, I'm testing with tank off so don't think the tank is the problem, I've taken each carb apart and cleaned jets and checked fuel chambers - the only thing I haven't done is seperated the carbs from each other, but I'm not sure how to do this.
At a last resort will either buy another carb off ebay for £25-£35 or give bike to mechanic for £160 clean and fix (quoted if carb problem).
any help much appreciated