somewhat of a mystery
My '94 CR250, after jetting, usually starts on the 3rd kick with a choke. It does tend to load up a little and has to be cleaned out some. This bike is jetted a little rich compared to my '01 which may account for the initial loading up, but has no fouling problems.
My '01, after jetting, usually starts on the first kick with NO choke. This bike is jetted leaner than the '94. Doesn't smoke much or load up after starting.
The choke should enrichen the mixture for starting, so it hasn't made much sense to me why the bike that is jetted a little richer needs a choke and the leaner bike doesn't.
They do have a totally diffent carb. and the Keihin idle/choke circuit on the '94 is very crude compared to the Mikuni on the '01.
You may play with the jetting some more and like someone else mentioned, check the reeds. I was told that the '01 Honda reeds are prone to cracking.
Don't know if this is a common problem in the YZ's.
Scott