The CRF250RX uses a double-overhead-cam (DOHC) engine layout with a unique finger-follower rocker design. Together with the rest of the engine’s architecture (bore and stroke, intake tract, piston, and more), you get more power and a higher redline.
The CRF250RX’s 79mm bore and short 50.9mm stroke let our engineers create a high-revving engine with plenty of room for large valves. The engine breaths and revs—the two keys to making power in the enduro world.
The new CRF250RX features a bridged-box piston design developed on our factory racebikes. Why? The reinforcing structure between the skirts and the wrist-pin bosses lets this big-bore piston retain a light, strong construction and helps enable the CRF250RX’s high redline.
The CRF250RX’s clutch uses two different types of friction material. Why? The clutch can handle the increased power of the engine without being any larger. The lighter rotating weight is directly related to how fast the engine revs.
The DOHC cylinder-head design let our engineers straighten out the CRF250RX’s intake and exhaust tracts. The intake is shorter and just about arrow straight, and the exhaust flows more efficiently too. No athlete’s going to win a sprint if he tries to run while holding his breath, and it’s no different with your bike’s engine. You’ll experience both more power and better throttle response.
The CRF250RX’s dual-exhaust system is light, compact, and positioned close and low in the frame to take weight off the rear end and bring more mass to the bike’s center for improved handling. It also allows for more airflow, and that equals added horsepower.
This simple handlebar-mounted button lets you dial in engine power delivery character with a push of your thumb. Choose between Standard, Smooth and Aggressive, depending on course conditions.
Deep in the engine, there’s a special oil scavenge pump. While you may never see it, it helps keep the CRF250RX’s overall design compact.
Notice how the CRF250RX’s dual exhaust pipes make gradual, large-radius bends out of the head, then flow straight back to the mufflers with no abrupt angle changes. Getting the exhaust out of the engine—while still maintaining a tuned exhaust length, is the key to power, while the pipes’ low mass and twin-silencer design optimize the CRF250RX’s center of mass for superior handling.
Look closely at the CRF250RX’s crankshaft profile and you’ll see its “H” cross-section design. What’s up with that? Just like a structural “I” beam in an aircraft wing or a skyscraper, it boosts strength and cuts weight over a conventional crank’s shape—a big deal when you consider this part spins at over 14,000 rpm!
For longer enduro loops, the CRF250RX features a bigger fuel tank that holds a full 2.25 gallons.
Like the rest of the CRF250RX, the bike’s Lithium-Iron-Phosphate battery is both super light and high performing. In fact, it weighs less than half the weight of a conventional lead-acid battery.
Talk about smart: The CRF250RX features an ECU with special engine mapping for each gear. You can’t give an inch in this class, so having your engine deliver optimal power for each gear choice is one of the features that separates CRF250RX riders from the rest.
The 2019 CRF250RX uses a shared engine/transmission oiling design. Why? Combining the two systems shaves weight and helps make the engine more compact, especially when it comes to placing the right-side cam drive and the clutch so close together.
Light is right when it comes to a high-revving engine’s reciprocating masses. That’s why the CRF250RX uses titanium intake and exhaust valves. Plus, the valve angle is a super-narrow 20.5 degrees (included). Ovalized valve springs and long-wearing Diamond-Like Carbon (DLC) treated finger rockers complete the package.
Total air management means complete attention to how efficiently air gets through the intake, through the head, and out the exhaust. Eliminate losses here, and you make more power everywhere. And the best part? It’s free horsepower—you just need a bike with smart design.