Designing a dirt bike is never easy, but it seems that Yamaha has got the perfect recipe as it pulls it through, managing to release better performing competition bikes with each year that passes. For 2010, the YZ125 carries on further perfecting its already great features such as the engine and chassis. Even though not the most important model year because the bike was great from the very beginning, it does catch our attention once again and that is never a bad thing.

  • 2010 Yamaha YZ125
  • Year:
  • Make:
  • Model:
  • Engine:
    liquid-cooled, 2-stroke, reed-valve inducted
  • Transmission:
    Constant-mesh 6-speed; multiplate wet clutch
  • Horsepower @ RPM:
    39.0 Hp @ 11,500 rpm
  • Torque @ RPM:
    25.5 Nm @ 10,000 rpm
  • Energy:
    Mikuni® TMX 38
  • Displacement:
    124 L
  • Top Speed:
    100 mph
  • Price:



Just like virtually any other bike that is built to compete, the Yamaha YZ125 would have first been launched by following the simplest formula ever: a light chassis mastered by a powerful engine. There was no mistake in doing that, but it would have been a shame not to take it further and get the most out of it.

It is exactly what Yamaha did during these last years, ending up launching a 2010 model year that only needed an aluminum frame housing, ProTaper handlebars and front brake hose clamp – also made of aluminum – in order to reach the 208 lbs wet weight. Add titanium footpegs, gripper seat and you’re good to go.


2010 Yamaha YZ125
- image 333213
1981 Yamaha YZ125

The YZ125 is a well known model name at Yamaha as it has been on the scene ever since 1974, when it was recognized as being one of the best dirt bikes of that time. Originally powered by an air-cooled two-stroke engine fed through a Mikuni 32 mm TMX carburetor, all hosted by a steel backbone frame, there were no doubts that the new dirt bike will have a long and wonderful life, introducing many teenagers, and not only, to motocross riding.

In 1981, the powerplant was introduced to liquid cooling and case-reed so that the extra power and heat that came together with the 38 mm TMX Mikuni carburetor would be properly dealed with. The steel frame had a longer life (30 years, to be precise) before it would be replaced by the twin spar aluminum alloy one. A benefic result was the significant weight reduction (190 lb dry), but this also made it harder to ride on tricky surfaces, so riders who were familiar with earlier models were about to go through an accommodation period which often introduced them to the track’s mud.

Another important unit that saw several changes during the years is the gearbox. The engine was small, so it couldn’t be mated to a four-speed tranny, leaving fifth and sixth speeds to be the solutions for faster sections of the track.

Perfect for AMA Championships, the Yamaha YZ125 has made a big name for itself and it plans on going strong in 2010 as well.


Racing against the Yamaha YZ125 and one against the other is any 125cc two-stroke motocross bike and 250cc four-stroke motorcycle ever to be produced by makers who actually feel like selling their products. It is a very well known fact that the podium dictates the sales charts and that is precisely what Yamaha aimed at.

So you’ll ask about the YZ250F and find out that this is THE Yamaha bike created as an alternative to the much older YZ125.

Honda is on the bumps and jumps with the 2010 CRF250R, but we would have loved to see the CR125 going strong today as the YZ125 does. The same thing applies to Suzuki and Kawasaki. They only offer 250cc four-stroke dirt bikes (the RM-Z250 and KX250F) instead of sticking to their former smokers.


2010 Yamaha YZ125
- image 333188
2010 Yamaha YZ125

Refreshing its design, Yamaha aimed towards a slender look with great finishing touches. Although it looks like all of the other, bigger bikes in the lineup, it is easy to identify on the track due to the specific two-stroke exhaust and, if it has the luck of riding alone in the front, the two-stroke noise.

It is aggressive and stylish, speaking about pure performance and modernity, something that not many Japanese dirt bikes manage to achieve by simply showing themselves at the start line.

As a 2010 model, it comes with new side panels and decals. These units blend perfectly together with the new two-tone grip seat and I didn’t even mention about the fenders. They stand up tall from the filthy tires, announcing those jumps that the wheel travel on this think can take on everything out there.

Not like the other Yamaha dirt bikes, the YZ125 comes only in the Blue and White color combination, something that takes a decision off your mind when willing to buy it.

Test Ride

2010 Yamaha YZ125
- image 333189
2010 Yamaha YZ125

Yamaha is keen on the two-stroke segment and I can understand why. Riding the YZ125 is like an incursion into the racing past of dirt bikes. It is something about the oil and gas mixture smell, the ease with which the engine starts and the specific two-stroke sound. You really can’t get enough of the Yamaha YZ125 especially if you’ve been dirt riding back in the glory days of the two-stroke engine.

Light, versatile and very easy to toss around, the YZ125 is destined to teenagers and adults alike even though the more potent YZ250 is also an important two-stroke model of Yamaha. The bike reacts to the rider’s commands fast and in a very natural way. You can really feel that they didn’t have much work done on the engine from the simple reason that it didn’t need it.

The bike is very compact and, as a rider, you feel that it is easy to work with while remaining stable and reassuring at all times. You’ll be virtually sitting on the gas tank in the short moments when you will actually sit on it and this keeps the rider alert and prepared to face the toughest riding conditions.

Being a two-stroke, the engine starts at the first kick as long as you open up the throttle while doing it. Unlike four-stroke engines, this banger requires some serious revving in order to deliver the best of it and you really have to get used keeping it there. This means being in the right gear at all times and problem solved. Wait, does this bike even have a problem? Not at all! Once you get used to keeping the engine at its sweet spot and what gear needs to be selected for each of the track’s section, all 250cc four-stroke bikes will be struggling to stay behind you.

2010 Yamaha YZ125
- image 333190
2010 Yamaha YZ125

The front end lifts effortlessly from the ground, so in order to handle the bike as should, that 21-inch wheel must stay in touch with the dirt and the 19-inch rear one will always follow. This also applies when trying to improve your lap times. Keep the wheels on the actual track and the difference will be noticeable.

In the air (because you will want to get airborn at some time), the YZ125 remains stable and reassuring while you’ll be either opening the throttle a little bit or hitting the rear brake in order to give it the needed corrections for a perfect landing. Still, the suspensions provide plenty of travel (11.8 inches from the fully adjustable inverted fork and 12.4 inches from the fully adjustable shock) for tougher landings and you will need a 180 pounds heavy rider to even get close to bottoming out the suspensions.

With waved brake rotors – a 250mm one up front and a 245mm one at the rear – the YZ125 sure speaks about performance and these are actually the units which will put an end to the bike’s awesome performance on the track. As you can suppose, stopping power is enough to spare.

Overall, the Yamaha YZ125 is an aggressive piece of machinery that misses no chance to impress while it stands out as the noisiest and most versatile dirt bike out there.


Decided to go for it? If you’re good on sponsors, the $6,090 starting price is a simple formality and if you buy it simply for fun on the backyard’s track, it will still prove advantageous. Quality to price ratio has always been reduced to a minimum when it comes to these bikes and don’t be surprised if you will see both father and son riding on their own Yamaha YZ125s.


2010 Yamaha YZ125
- image 333187
2010 Yamaha YZ125

For those who stay keen on two-stroke performance, Yamaha doesn’t abandon the YZ125 fight and yet offers an improved product, year after year, just how it all started more than 3 decades ago. There are sides who encourage the four-stroke engine development (which already happens, so I don’t really catch the purpose) and sides who remain faithful to the two-stroke engine and it often happens to see the first camp lose members in favor of the second once they experience a bike such as the Yamaha YZ125.


2010 Yamaha YZ125
- image 333185
2010 Yamaha YZ125


Engine and Transmission

Type: 124cc, liquid-cooled, 2-stroke, reed-valve inducted
Bore x Stroke: 54.0 x 54.5mm
Compression Ratio: 8.6 10.7:1
Fuel Delivery: Mikuni® TMX 38
Ignition: CDI
Transmission: Constant-mesh 6-speed; multiplate wet clutch
Final Drive: Chain Drive

Chassis and Dimensions

Suspension/Front: Speed-sensitive system inverted fork; fully adjustable, 11.8-in travel
Suspension/Rear: Fully adjustable single shock; 12.4-in travel
Brakes/Front: Hydraulic single disc brake, 250mm
Brakes/Rear: Hydraulic single disc brake, 245mm
Tires/Front: 80/100-21-51M
Tires/Rear: 100/90-19-57M
Length: 84.1 in
Width: 32.6 in
Height: 51.8 in
Seat Height: 39.3 in
Wheelbase: 56.8 in
Ground Clearance: 15.2 in
Fuel Capacity: 2.1 gal
Wet Weight: 208 lb


Warranty: 30 Day (Limited Factory Warranty)

Features & Benefits

2010 Yamaha YZ125
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2010 Yamaha YZ125

Key Features:

  • A light aluminum frame housing an amazingly light and compact engine results in an awesome power-to-weight ratio.
  • The YZ125 is ready to race out of the crate, complete with a ProTaper® aluminum handlebar, titanium footpegs and gripper seat.
  • A pure motocross machine, the light and nimble YZ125 is the perfect choice for riders stepping up from the 85cc class.

  • Engine:

  • Reed-valve spacer improves acceleration across the entire powerband.
  • Amazingly compact 124cc reed-valve-inducted two-stroke helps produce an awesome power-to-weight ratio.
  • Patented YPVS® power-valve system combines crisp, hard-hitting bottom-end acceleration with strong midrange and eye-opening top-end.
  • 38mm Mikuni® TMX carburetor gives excellent throttle response and serious horsepower.
  • Six-speed, close-ratio transmission optimizes gear ratios for maximum performance.
  • Digital CDI ignition system delivers precise spark and monitors engine speed to ensure optimal timing for faster, stronger response during hard acceleration.
  • Large-capacity radiator features a 10-row core with four louvers to deliver maximum cooling efficiency at all performance levels.
  • Primary kickstarting ensures easy restarts in any gear.
  • Trick, works-style clutch lever features race-spec barrel adjuster for on-the-fly adjustability.

  • Chassis/Suspension:

  • YZ250F-style front-brake caliper and wave-style front and rear discs minimize unsprung weight and provide excellent stopping power.
  • A carefully engineered, advanced aluminum frame and swingarm give the YZ125 the best handling in its class.
  • Speed-Sensitive System 48mm KYB® fork; damping force is controlled by piston speed which provides a smoother, more precise ride.
  • Removable aluminum rear subframe is constructed of square-section tubing for reduced weight.
  • Rear, fully adjustable KYB® shock features a super-light titanium shock spring and reduced-friction Kashima coating of internals. 12.4 inches of travel, separate adjusters for high- and low-speed compression damping, and a full lock oil rebound system for increased comfort all add up to fantastic rear wheel control and a sweet ride.
  • Tapered rear wheel spacers ease sliding the rear wheel into place for quicker tire changes.
  • Premium Dunlop® knobbies offer race-spec traction and wear.

  • Additional Features:

  • Special-design “gripper” type seat and fuel tank, forward-canted steering crown and low ProTaper® handlebar all help create greater freedom of movement and more comfortable ergonomics for riders.
  • Wide, cleated, folding titanium footpegs are lightweight and provide excellent comfort, grip and ground clearance.
  • Use of light box-head bolts throughout the chassis eases maintenance while reducing weight for increased performance.
  • Premium drive chain has gold-colored plates for outstanding looks.
  • Wide-diameter fuel tank cap for easier refueling.
  • Repackable exhaust silencer.
  • Durable, comfortable handlebar grips.
  • Maxx Biker
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      (1) posted on 02.29.2012

    message to Tommi Mcrae:
    The yz125 has the same frame to an yz250 and is the same size, trust me it’s pretty tall.

      (359) posted on 09.29.2010

    I’m just saying it’s about time that we can get a car (besides the Jetta TDI) that looks normal, but can still get just-as-great Fuel economy as the wedges.

      (798) posted on 08.10.2010

    good for racing so small and looks lighter.

      (406) posted on 07.27.2010

    It has a simple design but powerful engine.

      (824) posted on 11.19.2009

    125 dirt bikes are fun and this YZ125 sure would be sweet for some dirt racing.smiley

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