Rieju 50 MRT (2009-2021): A Generation Built for Off-Road Passion and Urban Agility

Spanning over a decade of production, the Rieju 50 MRT series has carved its niche as a versatile two-stroke machine equally at home on muddy trails and asphalt playgrounds. Designed with Spanish flair and endurance in mind, this 50cc platform caters to both budding riders and seasoned enthusiasts seeking lightweight agility. Having spent time with several variants—from the knobby-tired Enduro Pro models to the street-savvy SM Trophy editions—here’s why this generation remains a compelling choice in the small-displacement segment.

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Design & Ergonomics: Purposeful Minimalism

The Rieju 50 MRT’s design ethos screams functionality. Its double-cradle steel perimeter frame (detachable subframe on later models) balances rigidity and weight savings, tipping scales at just 85 kg (187 lbs) in its Enduro trim. Standing beside the bike, the 890 mm (35-inch) seat height on the off-road variants feels approachable for riders around 170 cm (5’7”), though taller riders might prefer the Supermoto’s slightly lower 870 mm (34.3-inch) perch.

Color schemes evolved yearly—from bold yellows and oranges in early models to sleek black/white/red combos post-2017—but all share a no-nonsense aesthetic. The digital dash (introduced around 2013) is refreshingly legible, displaying basics like speed and fuel. Storage? Forget it. This is a machine stripped to its essentials, though the 6.3L (1.67-gallon) tank ensures reasonable range for its class.

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Engine & Performance: Two-Stroke Spirit, Modern Refinement

At its heart lies a liquid-cooled 50cc two-stroke—primarily the Minarelli NG-derived powerplant—paired with a Dell’Orto PHBN 16 carburetor. Don’t let the small displacement fool you; the engine’s 6-speed gearbox (standard post-2010) lets you wring out every drop of its spirited performance.

Key Characteristics:

• Throttle Response: The carbureted setup delivers crisp acceleration, though cold starts occasionally demand patience (kick-only, always).
• Power Band: Peak power arrives around 8,000 RPM—a narrow but exhilarating window that rewards aggressive clutch work.
• Soundtrack: The stock exhaust emits a raspy, classic two-stroke snarl, though aftermarket pipes (like the racing mufflers on Pro models) amplify the character.

On tight trails, the engine’s low-end grunt shines, tractoring up inclines without bogging. Switch to Supermoto trim with its 17-inch street tires, and the MRT becomes a hooligan’s delight—zipping through urban corners with a flickable 1380 mm (54.3-inch) wheelbase.

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Chassis & Handling: Precision Meets Durability

Rieju nailed the geometry here. The Enduro’s 21-inch front/18-inch rear spoked wheels (with 80/90-21 and 110/80-18 tires) float over rocks, while the Supermoto’s 17-inch alloys (100/80-17 front, 130/70-17 rear) offer razor-sharp turn-in.

Suspension & Brakes:

• Front: Earlier models used 37mm conventional forks; post-2011 Pro editions upgraded to 40mm inverted Marzocchi units—plush over roots yet firm mid-corner.
• Rear: The PRS (Positioning Reservoir System) mono-shock (adjustable on Competition trims) soaks up landings without wallowing.
• Stopping Power: Galfer Wave discs (200-220mm) with dual-piston calipers provide confident bite, though organic pads (easily swapped via MOTOPARTS.store) improve feel in wet conditions.

The steel frame’s flex is perceptible at extreme lean angles but contributes to the bike’s forgiving nature—ideal for learners. At 85 kg (187 lbs), it’s effortless to manhandle through tight singletrack or U-turns.

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Competition: How the MRT Stacks Up

1. Derbi Senda DRD X-Treme 50

• Similar Minarelli engine but air-cooled. Lacks the Rieju’s liquid-cooled consistency during prolonged thrashing.
• Softer suspension suits beginners; less capable for aggressive riding.

2. Aprilia RX 50

• Shares the liquid-cooled two-stroke ethos but with Sachs suspension (stiffer than Rieju’s Marzocchi).
• Pricier maintenance; Aprilia parts are less ubiquitous than Rieju’s cross-compatible components.

3. Yamaha DT50X

• Four-stroke reliability but lethargic compared to the MRT’s two-stroke punch.
• Higher seat height (910 mm) less friendly for shorter riders.

Verdict: The Rieju strikes a balance between the Derbi’s accessibility and Aprilia’s performance, with a parts ecosystem that’s forgiving for DIYers.

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Maintenance: Keeping the Two-Stroke Alive

Owning an MRT means embracing its mechanical simplicity. Key considerations:

1. Engine Longevity

• Oil Injection: Models with separate mixture systems (post-2011) require periodic checks of the oil tank and lines. Pre-mix riders: stick to 50:1 ratios.
• Piston Replacements: Expect to swap pistons every 80-100 hours of hard riding. MOTOPARTS.store stocks OEM and forged upgrades.

2. Carburetor Care

The Dell’Orto PHBN 16 is reliable but sensitive to ethanol-blended fuels. A $20 rebuild kit (jets + gaskets) solves most idle issues.

3. Suspension Tuning

Upgrade to progressive springs ($120/set) if bottoming out on jumps. PRS shock oil changes every two seasons prevent fading.

4. Brake Upgrades

Swap stock pads for sintered variants (Galfer #G1376) for improved wet-weather performance.

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Conclusion: A Legacy of Adaptability

Whether you’re carving forest trails on an MRT Pro or scraping footpegs on an SM Trophy, this generation’s charm lies in its raw, mechanical honesty. It’s a bike that rewards tinkering—a blank canvas for upgrades like big-bore kits or adjustable levers (both available here). While modern electric starters and fuel injection have since dominated the market, the MRT’s kick-start soul and analog thrill ensure its cult status endures.

Ready to personalize yours? Explore our curated selection of Rieju 50 MRT performance parts and accessories today.

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Specifications sheet

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