My 2009 atv has developed some running issues. It backfires and has no power. I though it may be bad gas so I drained it and put new premium in it and still ran poorly. I did the spark plug as well. I took it for a ride at night with the lights on and noticed when the lights were dim It ran terrible and then the lights would go bright and would run great for a few seconds and it would continue to go back and forth but mainly ran poorly. Any suggestion or help would be awsome

Thx