Hello everyone! I have a 2011 Polaris Sportsman 500 carb with 336.2 hours and 4439 miles, I’m having an issue with the atv bogging and backing firing sometimes when letting off the throttle after holding it at 3/4-full throttle for a short time cruising down back roads so it’s not really under much load, it only bogs and back fires for around 10 seconds then it gains its power back and runs as normal until I get back on the throttle for a while again, I’ve checked the valves and they are in spec, something I’ve noticed this past summer right before the bogging issue started is it seems to burn oil slightly, I ride about 2-5 times a month in the summer and have to put a little oil in it once every 1-2 months to keep it between the lines, something i noticed today was at the very bottom of the dipstick the oil looks milky which is new because I check the oil just about every time I ride, after seeing that I checked the coolent level and that seems fine, I do ride in a good amount of water sometimes but not usually over the dipstick, other notes are the air filter is original but I cleaned it not to long ago and the fuel filter and spark plug are both original as well, I plan on changing that stuff soon because of the high mileage, and the carb has never been off and cleaned the atv is a bomber sorta speak but still in fair condition so I’d like to keep it running good, I keep it maintained but probably not as good as I should, it also seems to lack power over all a little, and I’ve also replaced my belt probably 400 miles ago and looked over the clutches which seem to be working fine My guess on all of this is a blown head gasket or base gasket but the atv doesn’t smoke, I’m pretty good at understanding and working on 2 strokes and some 4 strokes so i think I can replace the head and base gasket, I’ve seen rebuild kits on eBay that come with the jug, piston, rings, cam chain tensioner, and the gaskets for around $120 I’m wondering if that would be worth doing or if those cheap Chinese parts will probably kick the bucket real fast I’m just trying to get it running like it used to without putting a ton of money into it because as I said it’s a bomber. Sorry if this is all long and confusing I’m just trying to give you as much info as possible so maybe I can get these issues sorted out, thanks!!