I have a 1996 Polaris Magnum 425. Running really rough, burning way too rich, and exhaust getting cherry red. I have had one person look it over. They took the carb apart and couldn't find anything wrong. They went thought the whole exhaust system, can not find anything wrong. Any ideas? I am ready to pull my hair out. We had this 10 years and never a single problem til now.  We know another person with the Polaris Trail Boss, theirs is doing this same thing.  What is going on? Anyone have a clue?  

if it's getting too much fuel then the problem has to begin in the carburetor.

maybe something was missed upon inspection

check the floats for cracks.
if they are cracked then they will fill up with fuel and not shut off the flow when the bowl fills.

also check the needle in the carb.
sometimes you can lose the keeper on it and it will allow too much fuel into the cylinder.