Keihin PWK enables you to have larger diameter for air intake compare to standard diameter of standard carburetor. Most <150cc bike has 28mm diameter for the air intake where Keihin PWK has a range of 33mm up to 39mm. Larger size means higher fuel and air that can be burnt to give more power to the engine!
To find out more about Keihin PWK carburetor, I have listed out the best site for you to find more information about it:
1. Keihin PWK U.S.
2. Sudco – Keihin PWK Carburetor
3. Keihin PWK Jetting and Dimension
4. Keihin PWK 28 Parts Catalogue
5. Keihin PWK 33, 35, 36, 38, 39 Parts Catalogue