Right, so I have been dealing with this pretty much since I have owned this bike, a 1954 comet. The bike starts easily when it is cold, choke slides closed 3 pokes on the tickler.
Once is it is warmed up it will not start until it has cooled down.
The bike runs great if I can manage to not kill the engine, power is excellent, no problems exceeding 60 mph.
There is no misfiring once off idle, but it will not idle for more than a few seconds.
The spark plug looks OK, a bit rich, but no different than my other bikes, Norton Commando, Yamaha XT500, both of which start easily hot or cold.
There is always spark when checked, hot or cold, magneto timing is where it should be.
It seems to be carburetor, everything else including cam timing has been checked and what it should be.
It is very easy to mess up the carburetor so that it will not start, hot or cold. The set up that enables cold starting is slide lifted about 1/16 or a bit less, air screw turned out 1 1/4 turns, anything deviating from this setting will not work hot or cold.
The carburetor is the original 229 amal, it has been thoroughly cleaned ultrasonically, all the fuel and air passages in the jet block are clean and open.
It is just about impossible to resolve the problem given that once the bike has started and warmed up, I try an adjustment, it dies, and then won't start again until cold, so back to square one.
My next move will be to replace the carburetor with something else, probably a Mark II, but before I do that I want to check with the forum to see if there is something I am missing.
Once is it is warmed up it will not start until it has cooled down.
The bike runs great if I can manage to not kill the engine, power is excellent, no problems exceeding 60 mph.
There is no misfiring once off idle, but it will not idle for more than a few seconds.
The spark plug looks OK, a bit rich, but no different than my other bikes, Norton Commando, Yamaha XT500, both of which start easily hot or cold.
There is always spark when checked, hot or cold, magneto timing is where it should be.
It seems to be carburetor, everything else including cam timing has been checked and what it should be.
It is very easy to mess up the carburetor so that it will not start, hot or cold. The set up that enables cold starting is slide lifted about 1/16 or a bit less, air screw turned out 1 1/4 turns, anything deviating from this setting will not work hot or cold.
The carburetor is the original 229 amal, it has been thoroughly cleaned ultrasonically, all the fuel and air passages in the jet block are clean and open.
It is just about impossible to resolve the problem given that once the bike has started and warmed up, I try an adjustment, it dies, and then won't start again until cold, so back to square one.
My next move will be to replace the carburetor with something else, probably a Mark II, but before I do that I want to check with the forum to see if there is something I am missing.