The first H.O was the 98 Scrambler. High duration cam with the 40mm crab. sportsman had the up grade 3 years later in 2001.

Not all non H.O had the cam thing My dads 97 Sportsman 500 had 6000 miles on it before he sold it. Its very important to stick with 0w synthetic to get the oil to the top end as quickly as possible on cold starts.

As for power I rode his 500 many time and the H.O has a quicker 4 machine length acceration up to its 3-4 mph faster top out speed. The H.O is quicker but does not make a fool of it. I think the 500 is rated at 31hp and the H.O is 35.

My dads 500 could get 105 miles on it's 5.25 tank while my H.O only got 90-95 miles.