Hi guys-------- is that a 1953 bike or a modern "53" plate ie a 2003 bike ??---If it's the 2003 bike you can drain the float-bowl into a container by removing the big screw at the bottom of the float-bowl..You will soon tell if there are globules of water rolling around in the bottom, underneath the layer of petrol...If this has been a winter lay-up and in a cold garage with, say half a tank of fuel in then chances are it's the E5 fuel "layering out" with the moisture sinking to the bottom...I've extracted this from the link given later on}------------------------ 1) Water accumulation in the fuel tank - ethanol absorbs water from the air. The water condenses in the fuel tank and will pull the ethanol out of suspension with the petrol. This is bad news because it strips the octane out of the petrol, leaving you with a layer of octane-poor fuel on top and a water-ethanol layer mixture on the bottom. If this gets sucked into the combustion chamber, you will have poor starting and very rough running with potentially engine damage.
2) Deposit is like to build up - Ethanol when mixed with water readily forms Gums in the fuel system much quicker than fuel without Ethanol. These Gums coat fuel system components including filters, carburettors, injectors, throttle plates and will then form varnish and carbon deposits in the intake, on valves, and in the combustion chamber.----------------------------------------------------------------------------------------------------------- The link is here}-----
http://www.frost.co.uk/protect-your-veh ... st-ethanol ---------------------------I had EXACTLY these symptoms earlier this year and found water in the tank when I hadn't even washed the bike or had it near any soucrce of water at all.... I removed about an egg-cup full from approx. half a Classic 500 tank...I drained the tank completely and re-filled with the "super" grade... I also gave the carb a full strip, "sonic" wash and re-build...So far ??------------OK..
