Jay, one of the symptoms (needing choke to hot-restart) matches lean mixture when starting better than it does anything else, but to sort these things out reliably it is often best to eliminate other basic faults; sometimes you get a mixture of causes combining to give a specific fault. Hard starting is also sometimes caused by one of the valves having negative clearance, or weak spark (at higher speeds the magneto usually does better than it does at starting speed). I think jet obstruction is fairly unlikely in this case because the carburetor has been replaced recently. I haven't checked yet whether the fuel filter was replaced as part of the carburetor change; the fuel filter is sometimes the culprit on this engine. The choke not closing, a clogged fuel filter, or an intake pipe air leak are the best guesses I could make at this point - but I'd rather not start chasing guesses until we know we have a sound base engine.
One of the objectives here is to end up with an archive case on this problem that will be helpful to others. If we follow a fairly standard diagnostic process (without going overboard and ignoring major symptoms, the way manufacturers' process charts usually do) we will probably get the best archive outcome, and matts156 will probably get an orderly progression toward a solution - which may be useful for him in future situations.
