Brian's question about fuel running from the top of the jet block locating slot would normally indicate the float level is too high......However if the float needle is not seating well enough, the fuel will continue to rise causing the same condition. This also happens when a bike is left on a side stand and the taps are left on, or are leaking internally......... The upper red sealing washer in the picture above, is a standard Amal part probably around 40 to 50 thou thick.......I have seen home made ones where the ID was too small, and this effectively blocks off fuel delivery to the pilot jet........a nice one to catch out those who aren't aware.......Note also the the large plated cap nut that holds the jet block to the main body comes in several different heights........so the wrong one will upset the float height.......This applies to the 276 and 229/289 carby's.........A bit more useless info.