2008 Foreman 500 Carb Help

I was having a problem with the old carb and there were quite a few things wrong with it so i went out to honda and bough a brand new one from them put it in the bike and fired right up. The problem i seem to be having now is that at WOT the bike seems to bog down a bit. I pulled the plug after about a 20 mile ride and it was very dark almost all black the bike has a 1 1/2 Snorkel. Do i need to be running a smaller main jet or is this a Air/Fuel Screw Setting

Thanks