The reason I ask is that I finally got a 40mm carb for my non-HO Sportsman 500, and I'm about to install it. I'm trying to figure out if I need to jet it a little leaner since it's the non-HO cam, and it's not going to let as much air into the cylinder (or out). I found stock jetting for my altitude for the stock HO is a 150 main. Should I just start there, or should I go with a 145.

Thanks,

Mike

 

I think you should start with the same jet that's in your non-HO since you're already at a fairly high altitude. Camshafts with more lift and duration will require more fuel for greater airflow. Just how much jet you'll need will have to be determined by a plug chop, wideband or other acceptable method of fine tuning the main jet.