New and need help with cooling system

[96sport400l]

I just recently bought a sport 400. This is my first quad, when i test drove it was my first time riding a quad. I have done minor work on cars but that's it. When I first got it I thought that it had carb problems(at least that's what a buddy said the issue could be). I cleaned it out,replaced the jets and reeds. Come to find out it was really over heating. i found this out because the piston cracked... not fun when you a mile in the woods. Its a good thing my truck has four wheel drive. I then got it bored out and bought a new piston. i put it all back together and it is running now. Before i really go play with it i wanted to know what could be making it over heat, so i can check it out now and not have to replace any ring or anything. Any pointers would be a great help. Thank you

[Bruce!]

Welcome to the board!

[sportsman550]

Welcome to the forum!

[4getful2]

Check the radiator fins ,front and rear,making sure they are clear of any mud,all it takes is a garden hose(no high pressure) and a good soaking to clear them. Check the fan operation.

[96sport400l]

I just checked the fins, there wasn't any that looks like they were bent or broken. It did have some mud on it so i cleaned it off. The fan is on a switch that i have to manually turn on and off(the guy before me set it up). It works fine, turns right on and has good speed. I keep it on unless I'm going through water. Would a bigger fan help?

[res2cue]

Cooling system could be air bound.
Drive the front end up a steep hill, park it and let it run with the rad cap off.
also on the water pump there is a bleed screw, un do it just enough till fluid starts coming out. Had to do this to a buddys 400 machine. Was air bound and over heating.
hope it helps