All about choosing the best supercharger pulleys

Reliability Over Performance

Here at Kawi Performance, we prioritize reliability over performance. It’s plain and simple—would you rather ride a working jet ski or one that leaves you stranded for a season? I thought so…

Why OEM Size is the Best Choice

If you want reliability, stick with the stock size! The OEM pulley is on your machine for a specific reason. It delivers a maximum of 15 pounds of boost which is exactly what Kawasaki designed their tune for. Since your machine does NOT have an oxygen sensor, it has no idea when you add boost. Adding boost leans out your AFR, thus reduces engine life or result in engine damage.  

What is Runout?

For those unfamiliar with runout, here’s a simple explanation:
Imagine a bicycle wheel propped up in the air. When you spin it by hand, it looks fine, right? Now, imagine that the tire has 1 inch thicker rubber on one side than the other. When you spin it, it wobbles. If you ride that bike, it would be uncomfortable, vibrate more as you go faster, and put extra stress on the bearings.

Your pulley works the same way on the supercharger—though on a smaller scale. Even slight runout can cause vibrations, bearing wear, and belt wear, leading to performance and reliability issues.

Why Choose the KP OEM-Size Pulley?

If you’re sticking with the OEM size (which you should), don’t go with the original—go with the KP OEM-size pulley. Here’s why:

• Lighter Design: Made of aluminum for reduced weight
• Anti-Wear Coating: Protects against belt wear and salt corrosion
• Near Zero Runout: Provides a smoother, more reliable ride

This means less mass, fewer vibrations, and better durability.

What About Smaller Pulleys?

You’ve probably seen pulleys that are 1-3mm smaller than OEM. Here’s why they aren’t the best choice:

• Increased Boost Requires More Fuel – Your jet ski doesn’t automatically adjust for this like a car would. Slapping a smaller pulley on your machine without a tune specifically made for that size, will result in a leaner AFR.
• No Oxygen Sensor Adjustment – Unlike cars, your jet ski runs within a fixed loop of parameters, meaning it doesn’t adjust fuel delivery on the fly. It will spray fuel according to the factory parameters, which means it “thinks” you have a stock size pulley.
• Potential Engine Damage – Running lean (too little fuel) can harm your engine unless you have a specific tune to compensate.
• Minimal Speed Gains – A 0.5-1 mph increase isn’t worth the risk of reduced reliability.