I'm currently looking at used 2000 Kawasaki Prarie 400 2x4 and a Polaris Magnum 325 2x4 The prarie has a liquid cooled and the magnum has a air cooled with oil assisted fan i'm going to be using the atv for pulling a 500 pound mower on the back and doing some trail riding and recreational riding and i was wondering which one was better. Please help!!!!!!!!!!!!!!!!!!

 

In my opnion, for pulling the mower at slower speeds the liquid-cooled will be better, but if the quad was to be used at speed all of the time it would be ok to get an Air-cooled one.
I run an 500 ArcticCat at Idle speeds most all day 5 days a week and it has never ran hot but a co worker with a polaris that is Air cooled runs hot at least once a week

 

I'd go with the Liquid cooled, you will never have an overheated motor and they usually keep your motor cooler... which means that your engine is going to last ALOT longer.

If you aren't going too fast, you aren't going fast enough!

 

You'll never have an overheated liquid cooled engine. Well maybe my sp500 isn't overheating it's just getting real warm.

 

couldn't disagree with you more, my sp500 has run hot a number of times. And looking further under the polaris forum you'll find several examples of sp500's and other models over-heating.