Smoke show: Yamaha revise two-stroke YZ motocross range and reveal all-new YZ125

Yamaha are aiming to get the holeshot on the off-road racing competition with their 2021 two-stroke motocross range; revealing updates to the YZ85 and YZ250, plus an all-new YZ125 for good measure.

2021 Yamaha YZ125 in detail

Starting with the new YZ125, the mid-sized dinger gets a more powerful engine, revised chassis, slimmer profile and new look. Also promising better brakes and improved handling, Yamaha claim it’s the ideal machine for up-and-coming riders progressing through the discipline.

Related articles on MCN

• 60 years of Yamaha in Grand Prix racing
• Have a go at off-road riding
• Taking your first steps off road on an adventure bike

To help achieve this boost in performance, the two-stroke engine gets a new head, cylinder, and piston; plus a reshaped combustion chamber, shorter exhaust port and cylinder porting. Improving drive and usability is a revised exhaust power valve, complete with altered timing.

Yamaha have tickled the carburettor and installed a longer conrod and heavier crank, with changes also made to the gearbox and air intake to help make the increase in performance more manageable for the rider.  

Covering these internal alterations is revised bodywork, which also masks an tweaked rear frame that features a new mounting point for the pipe, and improved routing for incoming air. In the middle there is a slimmer tank, seat, and radiator shrouds – reducing the width between the rider’s knees by nearly 36mm for great control.

The changes don’t stop there. Low speed damping has been altered at the front and rear. What’s more, there’s a new two-piston front caliper and 270mm disc featuring larger diameter 25.4mm pistons and new pads said to give a 30% increase in contact with the disc.

Yamaha YZ250 changes

Like the 125, the 250 is now also 36mm narrower between the rider’s legs and features a flatter seat – said to make shifting your weight from front to rear an easier practice. Helping further in the bends is revised low-speed damping in the 48mm KYB front forks and rear shock.

Adding to this is better stopping power, with a new 270mm front disc working with a more rigid caliper, complete with larger diameter 25.4mm pistons. A new front pad also promises a 30% larger contact patch with the disc.

At the rear, the disc size comes down by 5mm to 240mm and is combined with a new caliper that saves just shy of 100g of the total weight. Much like before, there’s also improved bodywork, said to help enhance air intake efficiency.

YZ85 also improved

Away from the 250, the YZ85 is also improved with a new look and revised ergonomics. Starting with the bodywork, new aggressive plastics boast a similar look to larger YZ models, with the overall width reduced by 25mm at its widest point. It’s also a practical change, too with the front fender now directing more air toward the bike’s radiator.

There’s also greater ease of movement around the bike, thanks to a flatter seat and new five litre fuel tank. New side panels also use their rear vents to direct air into the airbox. Beneath all this lies a 570g lighter aluminium rear frame, and revised swingarm said to help improve chassis stability.

The rest of Yamaha’s motorcross line-up…

Fresh colours are available across the entire motorcross range, with the four-stroke YZ250F and YZ450F also receiving tweaks to their suspension settings and new rear sprockets. Changes to the engine characteristics can also be made quickly on your phone via the Yamaha Power Tuner system.