Ive only had this atv for the summer ive put 700 miles and i changed the oil as recomend but since its become cold it seems to smoke a litte but its not blue its a very light gray smoke. any ideas.

also what can i do to get the thing to stop back firing
thanks

 

Any sign of fuel or coolant in the engine oil?
Compression/leak down test done yet?
For back firing, it might be too lean condition. At what speeds, does it occur the most often?