My son was riding his 2003 Sportsman 90 today when the engine suddenly began to miss. Shortly after it quit running all together. I had just filled it with gas. Thinking the gas may have had water in it I drained all the gas (I even turned the drain on the bottom of the carb and let that out as well) and put in fresh with no change. It will crank but it will not idle for long. It spits and sputters, backfires and then shuts off. It will not rev up. My son is super upset. Any ideas?

 

cdi box?