Steahly Flywheel Weight For KX450X

What it is

• 10 oz steel weight.
• Bolts directly to the flywheel.

The Steahly Flywheel Weight is just that -- it’s a simple, although very precisely machined piece of steel that bolts directly to the bike's flywheel and adds 10 oz of weight. This additional weight on the rotating mass of the engine is designed to reduce stalling, improve traction and have an overall calming effect on the power delivery. The piece retails for $159.95 and was tested on our 2023 Kawasaki KX450X.

How it works

• Simple install.
• Slightly slower revving, easier-to-ride power delivery.
• Better traction.

We chose a 2023 Kawasaki KX450X for this test since it’s an off-road model, but it’s not far from its motocross roots -- it's actually an identical engine package to the motcross bike aside from coming "stock" with the mellow engine coupler plugged in (though it still comes with the standard and aggressive couplers). We felt the power delivery on the KX would benefit from a little more flywheel weight and help the bike, especially in true off-road conditions.

Installation was pretty easy and only took about 20 minutes -- even if you do what we did and install it at the track. This also allowed us to ride it in the same conditions before and after to get the most accurate comparison.

Increasing the flywheel weight changes the power delivery, handling and even the feel of the bike. 10 oz is subtle but noticeable. On the Kawasaki, the additional weight made the bike a little easier to ride without really changing the feel. The revs build a little slower and make it easier to accelerate without breaking traction. The extra weight certainly didn’t turn the KX into a mellow trail bike. It’s still an aggressive 450 that can hit as hard as you want. It just gave the bike a more planted feel and made it a little easier to manage -- especially in conditions where traction is limited. 

Additional flywheel weight is often a matter of personal preference. Not everyone will appreciate the effects, but for those that do, the Steahly Flywheel Weight is a welcome addition. After spending time on the bike in various conditions we’re happy with the result and have no plans to remove it. We felt that it made the bike a little more off-road friendly without compromising its capabilities on the track and made it a bit more versatile which is a sought after characteristic for a bike that might be on a track one moment and then a rocky single-track the next.