Heelp

[04kfx400]

so i bought a 2004 kfx 400 of a mechanic i know, and after it started to get warmer and sledding season was done every so often i would try and go to the garage and start it but never did unless u gave it a shot of ezzestart, so we took the carb off and cleaned it and checked the jetting and its showing a 150 in the main jet and noticed the piolit jet wasnt screwed to spec so we make changed it, and then put it all back together and then my dad changed the choke on the cable and then it seemes to start but idles really high now, even if u mess with the idle screw, so its either no start or high idle, and i also noticed tonight that after idling for 4 mins the pipe where it comes out of the cylinder was turning red hot, is the fan suposed to run all the time or only when it gets to a certain temp?? the pippe is a kawi pipe put on by a kawi dealer when bought new.and help at all will be apreciated thanks