My KLE runs smoothly for a few minutes minutes (after filling carbs on PRI), then fades and stalls. The spark seems to be fine, even after stalling. Carby jets and float valves are new and clean. No fuel seems to get through the vacuum system. Can anyone tell me where the fuel vacuum comes from and what are possible remedies? No Kawasaki mechanics for hundreds of km here in regional Australia - so any advice very welcome.