slight stumble

[COLIN THOM <colinthom@shaw.ca>]

Hi Listers, my 75 TR6 ocassionally stumbles a bit leaving a dead stop. 
Otherwise, idle is smooth as silk, throttle response is good and it runs like a 
top. Once, when it lurched a bit worse than normal and one tire even chirped, I 
think I heard a backfire through the carb? Timing? Thanks in advance. Colin