well my guess would be that either he left the choke lever down and rode it or the spark plug is shot since its 2 yrs old(make sure the plug is gapped right) or maybe the diaphram in the carb is torn.

 

i ran it for a while during the winter with no coolant but i kept an eye on it and was running great. it has coolant in it now and yes it went down quite a bit but no it doesnt smoke. put a new spark plug in it and its running a lot better but i think ive narrowed it down to the choke cable bc the new sparkplug isnt great anymore and it should be in tip top shape. i think that the choke is sticking