Also check your carburetor. Chances are that either the main jet/needle jet assembly is partially-clogged, or you may have problems with your accelerator pump. The Mikuni carb on a Warrior has a small plastic arm built into the throttle linkage which is supposed to actuate the pump. Problem is, this plastic arm can wear out over time, and it will flex when the throttle is opened, preventing the accel pump from giving its required shot of fuel.
Take the black plastic cover off the side of the carb (below the throttle cable) and have a look. Have somebody work the throttle while you watch to see if the accelerator pump plunger is moving.