I drained the carbs before taking them off last October and they've been stored in a shoebox indoors since then. Any ideas what the problem might be?
Update on my fuel overflow problem. I lapped all the valves, which took absolutely ages and then reassembled the engine and checked and re-adjusted the valve clearances. I started it up this afternoon and it's still bloody leaking. In desperation I disconnected the fuel pump and started it up again, and it ran absolutely fine until the carbs emptied. So it doesn't seem to be a back-pressure problem, but rather a problem on the inlet side of the carbs. I've already replaced all the float valves and seals, so I'm at a bit of a loss as to what the problem is.Interestingly, when I dismantled the bike last autumn, I discovered that the wires to the fuel pump were connected in the classic bodger's "twist them together and wrap tape around it" method. This leads me to believe that the pump isn't exactly the correct one for the bike. It may just be that it's been replaced with a 98-01 pump at some point, or it may be a pump from a different model entirely. Does anyone know if the connectors are different between the different years? I know this is the case for some parts of the wiring loom, as my ebay engine had different connectors on the oil pressure sensor and the alternator.My first worry was that I might have reconnected the pump backwards, but I'm pretty sure that it wouldn't run at all if I'd done that. The pump seems to be operating correctly, ticks a few times when you turn it on, then stops.Next step is to try plumbing the fuel in direct from the tank to the carbs and see if it'll run properly then.
The bike ran fine with the pump disconnected and a temporary tank plumbed straight into the feed to the carbs. The pump had been shutting off ok, and it was only leaking when running, but as I've tried pretty much everything else at this point I've ordered a second-hand replacement pump off ebay and will give that a try.Plan B, if that doesn't work, then I'll have the carbs off (yet) again and give them another clean. I think that the most likely culprit at this point is a valve which is sealing just well enough to stop the fuel at atmospheric pressure, but not well enough to stop the fuel when the pump is running and the engine is vibrating.If Plan B fails then Plan C is to get the carbs cleaned and overhauled by a professional.