I have a 1988 arctic cat pantera 530l/c sled,and cant figure it out,last year it was good till the end of the year it was bogging for a while and then lost power and can only get about 5000 rpm and barely moves.I changed the stator,cdi,crank seals different clutches,weights ,springs,belts,and when you take the belt off I have alot of power so confused need to know what else I can do.

Have you checked plug color? More than likely start looking at carbs.

plug color is good

plugs look good,could it be timing?