I was out trail riding with my wife on our Polaris trailblazer for an hour. when it was warm/hot it wouldn't accelerate when I gave it gas. It would not rev and seemed as though it was going to die (boggy). I had to tow her back to the cabin. It was rebuilt a few years back and had run great up until this problem occurred. I use only non-oxygenated gas. It runs perfect until it got warmed up on the trail. thanks for your help for a non-mechanical rider.

 

I would recommend a compression test...then go from there.

 

Make sure the tank vent and carb vent tubes are clear and open. You can even open the fuel cap and see if it still does the same thing when hot.Plus when this happens check for spark also. It still sounds like what happens with low compression machines even though you said it was rebuild a while back. Most will run good until warm,then when warm the cylinder expands,piston rings don't have good contact with cylinder walls.Machines will bog,some will die until they cool back off. On this I'd do a compression check also to see where you stand on the top end.