i just bought a polaris sportsman 400, and would like to know what the HO is. it is a 2005

 

HO means high output. Pre 2001 model Sportsman 500s had lower power due to the BST34 carb and different cam configuration. HO models had the higher duration cam(same lobe height,longer duration) and the BST40 carb. These were the major differences that increased hp rating by 20%. Here's a comparison chart on the 2000 and 2001 model Sportsman 500s. 2000 Polaris Sportsman 500 ATVs Your 400 uses the same cam part #3086212 and the BST34 carb that the older model 500s used.The 400HO used the same cam as the 500 HO (#3085855) but still used the BST34 carb.In other words just changing to the different cam alone would technically make your 400 the HO version,but I wouldn't expect a dramatic power increase doing so while keeping the stock 34mm carb you have.

 

thanks for the info. get great feedback here.