I assume that the HO means "High Output". Does Polaris make a Sportsman 500, or are they all the Sportsman 500HO? If there are two versions of this engine, what is the horse power difference?

 

You assumed correctly. I've always had the understanding that the HO had 2 more HP than the non HO model (which I don't think is produced anymore). I could be wrong...

 

They started making the 500HO motor in 98 and put them in the Scrambler 500's after they realized that the Scrambler 400 was faster than the 500. In 01(?) they 500HO made its way to the Sportsman line as an option. After 02(?) all sportsman 500's were the HO. The HO has 20% more power over the standard 500 due to a different cam and carb and possibly something else?

 

my grandpa has a 97 just plain sportsman 500

 

I believe the only Polaris left with the standard 500 is the Ranger, but I hope that changes soon.