Yamaha YZ125: Master of the Motocross Track

For over half a century, Yamaha has been at the forefront of two-stroke motorcycle innovation, continuously pushing the boundaries of performance and engineering. At the heart of this enduring legacy lies a machine synonymous with raw power, agile handling, and competitive spirit: the Yamaha YZ125. This iconic motocross bike isn't just another model; it's a testament to Yamaha's unwavering commitment to the thrill of off-road racing, designed to propel riders directly into the 'VictorYZone' with its potent blend of cutting-edge technology and a rich racing heritage.

If you're looking to understand what truly defines a top-tier motocross experience, the YZ125 offers a compelling answer. It's a bike meticulously crafted for those who demand uncompromising performance, whether they're seasoned racers or ambitious riders making their mark on the track. Let's delve into what makes the Yamaha YZ125 a standout in the fiercely competitive world of dirt biking.

What Exactly is the Yamaha YZ125?

The Yamaha YZ125 represents the pinnacle of Yamaha's two-stroke development, embodying a design philosophy refined over 50 years. It's a highly specialised motocross machine, purpose-built for competition on dirt tracks and off-road terrain. The essence of the YZ125 lies in its incredible power-to-weight ratio, delivered by a lightweight, race-bred engine and an ultra-responsive chassis. Central to its formidable performance is the renowned Yamaha Power Valve System (YPVS), a sophisticated mechanism that significantly boosts torque and provides a broad, hard-hitting powerband, ensuring riders stay out front in any race scenario.

This bike is more than just a collection of parts; it's a finely tuned instrument designed for precision and speed. Every component, from the engine internals to the suspension, is engineered to withstand the rigours of competitive motocross while delivering an exhilarating and controllable ride. It's the ideal stepping stone for riders transitioning from smaller displacement bikes or for anyone seeking the unique thrill and responsiveness that only a high-performance two-stroke can offer.

What's New in the Latest YZ125 Motorcycle?

Yamaha doesn't rest on its laurels, and the YZ125 is a prime example of continuous evolution. The latest iteration of this celebrated motocrosser arrives with significant enhancements designed to elevate its already impressive performance. At its core, the YZ125 boasts a brand-new 2-stroke, 125cc powerplant. This isn't just a minor tweak; it features all-new engine internals, meticulously redesigned to improve durability, efficiency, and outright power output. Complementing this updated engine is a redesigned Yamaha Power Valve System (YPVS), which further optimises exhaust port timing for an even more potent and usable power delivery across the rev range.

Adding to its explosive acceleration is a new Keihin powerjet carburettor. This advanced carburetion system ensures precise fuel delivery, offering crisper throttle response and a noticeable surge in power when it's needed most. These updates collectively ensure that the YZ125 remains at the cutting edge of the 125cc two-stroke class, providing riders with the competitive edge required to dominate the track.

The Powerhouse: How Much Horsepower Does a YZ125 Have?

When it comes to raw power, the Yamaha YZ125 certainly holds its own in the motocross world. The YZ125 is specifically rated at approximately 34.5 HP (horsepower) and produces 32.4 pound-feet of torque. This places it firmly in the realm of high-performance dirt bikes, offering a thrilling and responsive ride that’s perfect for competitive racing.

To put this into perspective, the horsepower ratings of Yamaha motorcycles can vary dramatically, ranging from a modest 3 HP for entry-level models up to a colossal 198 HP for their flagship sport bikes. Most Yamaha engines typically fall within the 35-160 HP range. Let's compare the YZ125's power to other popular Yamaha models across various categories:

Yamaha Dirt Bike Horsepower

Yamaha dirt bikes generally range from 16 to 53 HP, depending on their engine size and intended purpose. The YZ125 sits comfortably in the middle, offering a significant punch for its displacement.

Yamaha Trail Bike Horsepower

Designed for recreational off-road riding, Yamaha trail bikes offer varied performance, from beginner-friendly models to more capable machines.

Yamaha Dual-Sport Bike Horsepower

These street-legal machines blend on-road versatility with off-road capability.

Yamaha Sport Bike Horsepower

Yamaha's sport bikes are built for speed and track performance, showcasing their most powerful engines.

Yamaha Naked Bike Horsepower (MT Series & XSR)

The MT (Master of Torque) series offers aggressive styling and strong performance.

Yamaha Touring Motorcycle Horsepower

Designed for long-distance comfort and performance, these bikes offer varying levels of power for different touring styles.

Yamaha Cruiser Motorcycle Horsepower

While their cruiser lineup has become smaller, past models offered substantial power for relaxed cruising.

Horsepower of Some Unique Yamaha Motorcycles

• Yamaha TZ750: A legendary 2-stroke race bike from the 70s, early models produced 89 HP, while advanced versions jumped to 120 HP.
• Yamaha Niken GT: A unique tilting reverse trike, its 847cc inline-3 engine delivered 115 HP.

As evident from these figures, the Yamaha YZ125, with its approximately 34.5 HP, is a powerhouse within its class and stands as a formidable contender for any rider serious about motocross racing, offering a perfect balance of accessible power and competitive performance.

Why the YZ125 Excels: Key Features and Benefits

The Yamaha YZ125 isn't just about its impressive horsepower; it's a meticulously engineered machine designed to provide an unparalleled riding experience. Pound for pound, few bikes offer the sheer fun and competitive edge of the YZ125. It serves as a perfect transition bike for those who've outgrown 85cc machines but aren't quite ready for the heavier, more powerful 4-strokes, or for anyone seeking the unique feel of a high-performance two-stroke.

Engine & Performance:

• Free-revving 125cc 2-stroke engine: This liquid-cooled, crankcase reed valve-inducted engine is compact and delivers class-leading power and acceleration. It's also remarkably easy to service, a significant advantage for regular track days and racing.
• Ceramic composite cylinder bore: A liner-less design where ceramic coating is sprayed directly onto the aluminium block. This innovation reduces weight, friction, and extends cylinder life, ensuring excellent heat dissipation for consistent power.
• Yamaha Power Valve System (YPVS): This patented slide-type power valve provides a dual benefit: solid low-rpm power combined with a strong top-end punch, by varying the exhaust port height and timing based on engine rpm.
• Mikuni TMX38 carburettor: Features a 'D' slide design that enhances overall power delivery and provides crisp throttle response across all rpms.
• 6-petal carbon fibre reed design: Contributes to stronger high-rpm performance and greater over-rev capacity.
• Close-ratio, 6-speed transmission: Optimised gear ratios matched to the engine output for maximum performance, outstanding acceleration, and efficient corner-exiting power.
• Lightweight exhaust system: Features a re-packable aluminium silencer, allowing riders to maintain the correct back pressure for peak engine performance while managing noise levels.
• High capacity, washable, dual-stage, foam air filter: Offers excellent filtering qualities and reduces maintenance costs as it's reusable.

Chassis & Suspension:

• Ultra-light semi-double cradle aluminium frame: This frame combines with the compact engine to create an awesome power-to-weight ratio. Yamaha maintains this design for its excellent 'rigidity balance', providing superb handling, a good ride quality, excellent stability, and responsive cornering.
• Adjustable KYB Speed-Sensitive System (SSS) 48mm inverted twin chamber fork: With 300mm (11.8") of travel, these forks are fully adjustable for compression and rebound damping (20-way each). The twin-chamber design prevents aerated fork oil from degrading damping, and low-friction seals ensure a smoother stroke. It also features a Transfer Control Valve (TCV) for enhanced damping from mid to full stroke.
• Monocross link rear suspension: Features a fully adjustable Kayaba piggyback shock with 315mm (12.4") of wheel travel. Adjustments include spring preload, rebound damping, and high/low-speed compression damping. A Kashima coating on the shock body reduces friction for improved suspension performance.
• New, larger, 270mm floating front disc brake: Coupled with new pad material and a 'wave' style rotor, it offers outstanding machine control, exceptional stopping power, and precise controllability.
• 245mm rear disc brake: Also features a 'wave' style rotor and an integrated master cylinder for strong stopping power with excellent feel and control.
• Lightweight, D.I.D. 21" front and 19" rear rims & premium Dunlop MX52 tyres: Provide excellent durability, reduce unsprung weight, and ensure optimal suspension performance and handling.
• Modern, aggressive styling: Including updated fenders, radiator shrouds, and side number plates, giving the bike a lean and sharp factory look similar to Yamaha's 4-stroke models.
• Race-ready features: The YZ125 comes out of the crate equipped for competition, featuring an aluminium handlebar, titanium foot pegs for excellent grip and ground clearance, and a gripper seat for enhanced rider control.

The culmination of these features makes the YZ125 a highly competitive and incredibly fun bike to ride. Its lightweight nature translates to nimble handling and reduced rider fatigue, allowing you to push harder for longer on the track. It's a pure motocross machine, perfectly balanced to deliver performance that truly allows riders to conquer dirt.

Technical Specifications: 2017 Yamaha YZ125

For those interested in the specifics, here are the key technical specifications for the 2017 Yamaha YZ125, which highlight its robust design and capabilities:

Frequently Asked Questions (FAQs) About the Yamaha YZ125

Is the Yamaha YZ125 a good bike for beginners?

While the YZ125 is a high-performance racing machine, it is often considered an excellent 'bridge bike' for riders transitioning from smaller 85cc models. Its lightweight nature and responsive two-stroke engine make it manageable for those with some prior riding experience, allowing them to develop skills before moving to larger, heavier 4-strokes. However, complete novices might find it a bit too powerful as a very first bike.

What's the maintenance like for a 2-stroke YZ125?

Two-stroke engines like the YZ125's are generally known for being simpler to maintain and rebuild compared to their four-stroke counterparts. They have fewer moving parts, which can lead to lower rebuild costs and easier 'top-end' overhauls. Regular maintenance, such as checking spark plugs, air filters, and mixing fuel correctly, is crucial for optimal performance and longevity.

Is the YZ125 a good racing bike?

Absolutely. The Yamaha YZ125 is a proven winner at the highest levels of motocross competition. Its explosive engine power, ultra-responsive aluminium chassis, and advanced suspension systems are all designed to give riders a competitive edge. It's a bike built to take you to the VictorYZone, as Yamaha aptly puts it.

What kind of riding is the YZ125 best suited for?

The YZ125 is primarily designed for motocross racing and aggressive off-road riding on prepared tracks. Its light weight, sharp handling, and powerful engine make it ideal for jumps, tight turns, and challenging terrain found on motocross circuits. While it can be ridden on trails, its true potential is unleashed in a competitive environment.

What is Yamaha Power Valve System (YPVS)?

The YPVS is a crucial technology on Yamaha's two-stroke engines. It's a mechanical system that varies the height of the exhaust port based on engine RPM. At lower RPMs, the port is smaller to enhance torque and provide a stronger bottom-end pull. As the RPMs increase, the valve opens, making the exhaust port larger for maximum horsepower and top-end performance. This system effectively broadens the engine's powerband, making the power delivery smoother and more usable across a wider range of speeds.

Conclusion

The Yamaha YZ125 stands as a powerful testament to Yamaha's enduring legacy in two-stroke motocross engineering. It's a bike that expertly combines a lightweight, agile chassis with a hard-hitting, race-bred engine, complete with the torque-boosting Yamaha Power Valve System. Whether you're an aspiring racer or a seasoned rider seeking the pure, unadulterated thrill of a high-performance two-stroke, the YZ125 delivers. Its continuous evolution, evident in the latest engine and carburetion improvements, ensures it remains a formidable contender on any track. With its blend of accessible power, precise handling, and straightforward maintenance, the Yamaha YZ125 is more than just a motorcycle; it's a gateway to competitive success and exhilarating off-road adventures, truly embodying the spirit of the VictorYZone.

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