Anyways, if you go into a Kawasaki dealer in Oz they won't say they have anything for a KR250A but I managed to get the two rubber seals for the fuel tap, one of which they had in stock. You just need to give them the part number. I found them all here:
http://www.kr250.org/KR_partsbook.htm
Then I went here, just for fun, and found what other bikes share the same part numbers:
http://fiche.ronayers.com/
Turns out quite a few Kawasaki models share those seals, and they should be ready for me to pick up at my local dealer tomorrow afternoon

One thing I'm still not quite sure of, does the fuel tap have two outlets, one for each carb, or do I have something unusual? Any pics would help a lot, ta.
Tony