I seem to be having the opposite problem... A HT-73, running amock. Once I get it started, it runs fine, till I go out for a run.. Once I slow for a stop, as soon as I disengage the clutch, the motor revs up, stays like that for more than a few minutes, then stalls-out. Now, I seem to remember, from dealing with an old Wheelhorse lawn mower, that 2-cycle engines tend to rev-up when they're beginning to run low on fuel, just before they shut-down from starvation. Then, it's difficult to start again unless I choke it.
I've stripped the carb down completely, flushing out every orifice with carb cleaner, a 22-gauge copper wire in any small hole I could find, but it still runs this way.. Very frustrating! ANy help would be greatly appreciated!