1999 450 Foreman

I have a 450 Foreman, after roughly 20 mins of riding it starts spitting and sputtering and only idle. When i try and give it gas it will barely move the tires, and the oil temp light flickers on and off. I can let iit set for a lil bit and it would fire back up and run just fine. I have wired the fan to a toggle switch for i hadn’t heard it kick on after it warmed up. I did a test ride today and it did the same thing and now it will turn over all day but wont fire and crank. it has been laid on its side and sat on its side for a lil while cause no help to put it back on four wheels by myself. I changed air filter and will put new spark plug in tomm, could oil have got into places it shouldn’t have while laying on its side for a short time? Any help is greatly appreciated.http://www.hondaatvforums.net/forums…_%20rocker.gif