New Keihin PWK 38mm carburetor Quad Vent Air Striker Carb With Jets. Works on either stock or modified engines, but performs best with modified engines running higher compression than stock. I highly tuning the carb prior to installation as it comes with standard jetting as stated. PWK Carburetor Standard JettinG. #165 / #175 Mains, and #45 / #55 Pilots.