I think all Polaris offers now is the high duration H.O cam as a replacement. The 500 Fuji built motor never changed since it came out in 1996. The only thing ever changed was the,flywheel , the high duration cam with a larger 40mm carb or EFI is the only difference between being a H.O or not. That change came out in 2001 for the 500 Sportsman and 1998 for the 500 Scrambler.

There were people making there own Sportsman 500H.Os before 2001 by replacing there carb and cam with the Scrambler's.

 

The only difference on the non HO cam versus the HO cam is duration only. The cam lobe height is the same on both according to the manuals. They still offer the updated non HO cam for 2000 models and earlier(3086212),but a lot of people have just gone to the newer 2001 and later(3085855) HO cam. OPT

 

OPT. Will the 3085855 work in my 97 Scrambler 500?

 

Yes,but don't expect any great power improvement unless the carb and intake manifold is changed that in a sense turns it in to a HO engine.The valves,springs,plates,keepers,etc are the same part numbers on the HO and non HO heads. The bigger carb and longer duration cam was the major difference. The cam lobes are the same height on the updated cam # 3086212 "recommended" for your model and the HO 3085855 cam. Only the cam duration changed.The choice is yours.At the shop I just replaced what was called for on each machine strictly for shop warranty reasons and to CMA

 

i think i have the same problem. is there a video to show how to open up the head and check?

Thanks
Greg