The Rieju MR 300i Platform: From GasGas Roots to the 2026 Models

The Rieju MR 300i and MR Pro 300i represent one of the more interesting developments in modern two-stroke enduro motorcycles. While the brand itself has been building motorcycles in Spain since 1934, Rieju’s recent growth in the off-road world is closely tied to the evolution of the MR platform.

Today, the MR 300i stands as a modern fuel-injected two-stroke designed for enduro and hard enduro riding. But the story behind the bike begins with a platform many riders already know well.

The Origins of the MR Platform

The foundation of the MR series traces back to the previous generation of GasGas enduro motorcycles, which were widely respected for their lightweight handling and strong, tractable two-stroke engines. These bikes developed a strong following among woods riders and technical enduro racers, particularly in the 250cc and 300cc classes.

When KTM acquired GasGas in 2019, production of the previous generation GasGas enduro platform ended. Rather than allowing the design to disappear, Spanish manufacturer Rieju purchased the rights to the tooling and intellectual property for those motorcycles.

Rieju began producing the bikes under the MR (Marathon Racing) name, allowing riders to continue accessing a platform that had already proven itself in demanding enduro conditions. Early MR models were very similar to the final generation GasGas bikes, but Rieju quickly began refining the design and integrating new technology.

The Move Toward Rieju’s Own Engineering

While the early MR models closely followed the original GasGas design, Rieju has gradually shifted the platform toward its own engineering direction.

One of the most significant developments was the introduction of fuel injection on the two-stroke models, creating the MR 300i. The system uses throttle body injection combined with electronically controlled oil injection, eliminating the need to premix fuel while maintaining the lightweight performance riders expect from a 300cc two-stroke.

Fuel injection also brought practical advantages for real-world riding. Riders traveling between elevations or riding in changing weather conditions benefit from more consistent engine performance and easier starting compared to traditional carbureted two-strokes.

Over the past few years, Rieju has continued developing the platform with updates to the chassis, suspension setup, and engine management. These refinements have gradually separated the MR lineup from the original GasGas design, turning it into a platform that reflects Rieju’s own development priorities.

The MR 300i Engine Platform

At the heart of the bike is a 293cc liquid-cooled two-stroke engine that remains focused on delivering strong, controllable torque rather than aggressive peak power.

The engine uses a counterbalanced crankshaft and case-reed induction system, paired with a six-speed wide-ratio transmission. Electric start and electronically controlled oil injection make the bike easier to live with while still delivering the responsive feel riders expect from a two-stroke.

What riders often notice most about the MR 300i engine is how tractable it feels in technical terrain. Instead of delivering a sharp, explosive powerband, the engine produces smooth torque that helps maintain traction when climbing steep or slippery trails.

This character has made the bike especially appealing to riders who spend time on tight woods trails, rocky climbs, and technical enduro terrain.

The 2026 Rieju MR 300i

For the 2026 model year, Rieju continues refining the MR platform rather than introducing a completely new design. The focus for this generation is improved rideability and smoother engine response.

Updates to the ECU mapping and ignition calibration help deliver smoother throttle response and more predictable power delivery at low speeds. These refinements are particularly noticeable in technical terrain where precise throttle control is important.

The electronically controlled oil injection system has also been further refined to improve oil delivery at lower throttle openings. This allows the engine to burn cleaner during slower riding while still providing proper lubrication under heavier loads.

While the overall frame and chassis layout remain consistent with recent MR models, suspension setup and tuning have also received small adjustments designed to improve traction and stability in rough terrain.

Visually, the 2026 models receive updated graphics and styling that distinguish them from previous generations while maintaining the aggressive enduro appearance of the MR lineup.

The MR Pro Models

Alongside the standard MR models, Rieju also produces MR Pro versions, including the MR Pro 300i.

These bikes share the same engine and chassis platform but are equipped with higher-end components designed for aggressive riders and racers. The MR Pro models are equipped with more premium suspension components, lightweight racing parts, and upgraded finishes.

The result is a more competition-focused version of the same platform, aimed at riders who want top-tier components directly from the factory.

A Modern Two-Stroke Enduro Platform

As the MR lineup has continued to evolve, Rieju has positioned the MR 300i and MR Pro 300i as modern two-stroke enduro machines that combine proven design with updated technology.

By building on the original GasGas platform while continuing to refine the engine management, chassis setup, and overall design, Rieju has developed a bike that appeals to riders who want the simplicity and lightweight feel of a two-stroke with the convenience of modern electronics.

For riders exploring technical trails, steep terrain, and long days in the woods, the MR platform continues to gain attention as one of the more interesting options in the modern enduro market.