The Banshee is a two-stroke ATV with a 347cc engine, while the KFX 400 is a four-stroke ATV with a 398cc engine. Two-stroke engines generally produce more power than four-stroke engines of the same displacement, and this is true in the case of the Banshee and the KFX 400. The Banshee's engine produces 35 horsepower, while the KFX 400's engine produces 30 horsepower.
In addition to having more power, the Banshee is also lighter than the KFX 400. The Banshee weighs 370 pounds, while the KFX 400 weighs 435 pounds. This weight difference gives the Banshee a better power-to-weight ratio, which makes it more nimble and responsive.
Overall, the Yamaha Banshee is a more powerful and agile ATV than the Kawasaki KFX 400. However, the KFX 400 is still a very capable ATV that offers excellent performance.