Honda Foreman ATV Back Fires

I have a Honda Foreman atv and at full throttle it backfires.

Has anyone else experience issues such as Foreman\s backfiring?

I messed with the Honda Foreman carb and it was clean. I put fresh gas in the honda atv. I am running out of ideas.

I did put new custom foreman exhaust on the atv a few months ago.