My quad seems to back fire quite a bit and quite loud when i go to slow down or gear down,wondering what it might be?

Backfiring on decel is usually caused by a lean idle mixture OR an air leak. If this
happened suddenly and the machine didn't do this before, I would suspect an
air leak. If it always did that, I would turn out the fuel screw to richen the idle
mixture until it stops. It could also be a plugged pilot jet, but then it wouldn't
idle at all.

it happens with my 97(i think) honda foreman... its always done that and sometimes scares the crap out of me... and also... the thing has about 18,500 miles on it and about 2500 hours on it... ive never heard of a four wheeler to have that many hours and miles on it... Opinion?

Ya i played around with the idle and seemed to have it right.Actually compared to it to my fathers quad which is the exact same,his seems to backfire to just not as much has mine.When i'm flying down a hill and usually shifting down is when it does it,and goes off like a gunshot,always makes my head shot right around to check.