Engine

KLX250/300s are far from the most powerful bikes on the market. They’re not designed for racing, enduro, or motocross. Instead, they’re “dual-sport” bikes, meaning they’re street-legal and must comply with modern emission and noise regulations. (By the way, these regulations vary by country, but we’ll get to that later.)

Most modern EFI KLX250s produce around 20 horsepower at the wheel, while KLX300s produce around 23 horsepower. Considering typical transmission and tire losses, this translates to approximately 22 crank horsepower for the KLX250 and 25 crank horsepower for the KLX300. These are the figures you’ll find on the motorcycle’s specification sheet.

In contrast, older generation KLX250/KLX300s with the same engine hardware could produce up to 33 horsepower at the crank (details here and here). So, what changed?

As mentioned earlier, the motorcycles now need to comply with stricter emission and noise standards. How did Kawasaki achieve this? They implemented several restrictions, listed here in order of decreasing limitation:

1. ECU Settings & Electronic Fuel Injection
2. Intake System
3. Exhaust System

By addressing these limitations, a KLX300 can achieve 30+ horsepower at the wheel (or 33+ horsepower at the crank). Reading the “engine” section will take less than 10 minutes and provide a good understanding of these restrictions and how to potentially overcome them.