2015 Yamaha YZ250

Introduction

• How good can a 10-year-old bike with a fresh look really be?

If there was one discussion the 2015 Yamaha YZ250 brought on, it was about history. This bike, with an engine that has not really seen a major update since the early 2000’s and a chassis that has been largely unchanged since going to an aluminum frame in 2005 is still wildly competitive for all but top pros and works awesome on a motocross track. Yes, even when compared to other 2015 machines of different makes and strokes. The YZ250 is pretty simple, very light and way up there on the fun scale for most riders who have been away from two-stroke power for a while. And Yamaha’s simple yet effective changes have brought the YZ into the modern era in style. Is that enough to make it competitive in today’s market? Can the YZ250 be competitive against the four-stroke competition?

Changes

• New look 2015 plastic to catch up to modern times.
• Upgrades mostly to the SSS KYB fork keep pushing the suspension.
• Small parts are upgraded to share parts from the four-stroke YZs, like the footpegs.

The standout change for 2015 is the new look. Resulting from a new front fender, front number plate, radiator shrouds, seat cover, air box, side panels and rear fender, the look can be described as current and now in line with the YZ four-strokes. Small changes since the introduction of the aluminum frame in 2005 have mostly been to bring over upgraded YZ four-strokes chassis components to the YZ two-strokes. Little things like the fork clamps, axles, controls and brake components. For 2015 the YZ gets the latest version of the KYB SSS front fork with valving settings derived specifically for the two-stroke. The footpegs have also been updated to the larger titanium ones found on YZ four-strokes.

Power

• Quick, crisp and responsive describe this two-stroke ripper.
• Using the clutch really boosts the power, and it works excellent.
• The sound of a properly jetted and tuned two-stroke comes standard.

The Yamaha YZ250 has always been praised for its power. Even back in the pre-four-stroke days where there was competition from five to seven other brands with two-stroke 250s. And this has not changed for the YZ. It makes a very meaty and strong, if not barky power from right off idle till the taper in the upper part of the top end. Over time and through slight jetting changes year to year, and now with the new airbox, the YZ is one of the crispest running bikes on the track. It is one of the best arguments against fuel injection it is so responsive. For riding around sea level, 91 octane pump gas and in our case Yamalube R2 at 40:1, you’d be hard pressed to get a better jetting setting.

The first thing someone not up on two-stroke engines might need to be reminded of is that this YZ takes a healthy boot on the kickstarter to get it to fire. And don't forget to twist the throttle a little when you kick, this isn't a pumper-equipped four-stroke and it does not have a compression release either. But the YZ fires as expected, choke required on cold days. It cleans out nicely and barks with authority when warmed. The tone is crisp and the longer muffler keeps the sound in check.

With a close-ratio five-speed gearbox and a conventional quick-adjust cable-actuated clutch, the pull is light and the feel is good. First is perfect for motocross but off-road riders might find it a bit tall in technical riding. The spread between gears is very linear and consistent with a fifth speed that was hard to get topped out even on the high-speed sections of Glen Helen’s National track.

Power is instantaneous and starts at a very low RPM just above idle, which for most MX riders was set to have the bike stall if the throttle was left unattended. This small tuning of something as simple as the idle screw gave the bike a bit more snap when coming on the gas, adding some idle smoothed the transition. The pull is very linear and very deliberate and the one thing that two-strokes do that is definitely different than four-strokes is having the torque curve build progressively along with the power curve where four-strokes have a more flat torque curve as horsepower rises. The RPM pays serious dividends on the YZ two-stroke and it makes a lot of power all the way to the top-end. If there was any common complaint it was that our faster test riders would have liked a little more over-rev and a little less sharp sign-off at the end of the pull. Pipes and mufflers can cure this for sure. Riders learned that quicker shifting was rewarded. And here lies the downfall of the two-stroke in its current configuration. It lacks the torque over such a large range compared to a modern fuel-injected four-stroke. That little extra bit of torque on the bottom and the power lasting over a longer RPM span on into the top is the advantage a four-stroke has, not the amount of power. Yes this 250cc bike makes nearly as much as a four-stroke of double the displacement.

Is it fast? Yes it is. Does it feel powerful? Absolutely. It has the kind of hit in the bottom and in the mid-range that can pop you up and over jumps in a short distance but it usually requires a little more clutch work or an additional shift compared to the same jump where you'd just roll the throttle on on a 450cc four-stroke. And compared to a 250cc four-stroke there is just plain more power that comes on quicker.  The YZ's powervalve helps extend the power and clean up the bottom end’s strength while allowing it to whale when at full noise. The best way to describe the YZ250 is to call it quick. The power is sudden, smooth and a very abrupt rush that does not get out of control.

Suspension

• The KYB suspension has always been good, now it is better.
• Over the years better bottoming control with added mid-stroke plushness to the fork have come along for the ride.
• There is nothing special about the shock-except that it works well and works like it should.

Yamaha’s KYB suspension setup across the YZ line has always been good, but lately with much of the competition going to an air-spring front fork, it has seemingly risen to the top. And for the most part, this is the same suspension that has been on the YZ250 since 2006 when the Speed Sensitive System (SSS) for appeared on the YZ. The shock is standard issue high performance with the normal adjusters, high and low speed compression and rebound as well as spring preload. Yamaha has had plenty of time to refine the setting and for 2015 the valving has seen a slight change--mostly to the balance the bike matching the upgrades to the front fork.

The YZ has a light on its wheels stance that is common to two-strokes since they are so feathery on the scale and when riding. You can feel the ground yet the suspension has a plush nature at the same time, we call it aggressively plush. Especially on hard packed tracks you get a little more bump feel. Still the YZ is comfortable but this is a race bike and it is set up as it should be.  Here the clickers, mostly compression front and rear, can be used to tame the feel and get better traction. But the softer the ground the easier it is to go stiffer on compression and be rewarded with a bike that you can really attack on confidently. The overall stroke and progression of the suspension is excellent and the bike bottoms predictably and is controlled when doing it.

We never got more than five clicks in any direction on any adjuster on the YZ on the many tracks we rode it. And most riders just got on and were happy, shrugging shoulders if asked about making the bike any better in the suspension department.  Picky riders would usually tune either the fork or the shock depending on the dirt conditions and the bumps or jumps but it was easy to do with familiar results from the compression and rebound changes. We were between 100-105mm of race sag and even this setting was less critical than on most modern bikes. That is a sign of a tuned package.

Chassis - Handling

• Light and powerful with table manners to go along with those excellent traits.
• The YZ250 is a very neutral handling bike--it does not stand out in any area.
• Some love the two-stroke characteristics, some need to get use to them.

Using the saying “light feeling” will get very overplayed here. Because that is the theme with this bike. For the amount of power the bike will put out and for how fast it feels, the YZ is ridiculously light. And a lot of it comes from the lack of rotational mass when the bike is making power at high RPM. All those extra spinning things inside a four-stroke and the additional RPM they spin at makes for a bike that is not so nimble. The YZ250 is light on the scale but even lighter on the track. It allows you to be able to muscle the bike around and actually make a difference. In the low to mid-speed sections of the track this is a rewarding feeling and really makes you feel confident. At higher speeds this can lead to a little bit of an unstable or unsettled feeling when compared to a four-stroke, though the YZ is as stable as anything. It just isn't as planted to the ground as the heavier bikes. You can let the YZ bounce around here a bit and not have to worry about it, you just have to get use to it.

In the turns there are a couple of factors at play. First the lack of any compression braking has the turn entrances either magical and flowing for those use to it or a delicate balance on using the rear brake to compensate. Luckily the YZ’s brakes are great. Not the best out there but since the bike is lighter they are plenty strong for the task. In the turn the bike is predictable and easily adjusted with body English or through a bit of throttle or clutch use. The light feel makes it easy to tame the ruts or get in or out as needed. All the time in the turns the front steering feels very light but the bike will follow the front wheel or slide at will—the power delivery is so crisp and responsive it just works in tandem. Turn exits are done on the rear wheel and steering mostly by rider’s shifting weight.

In bumpy stuff or in the whoops the YZ bounces around a little more than most bikes but it is because it isn't sticking to the bump as much as heavier bikes and when powering off them it is strong. It dances more which can feel awkward for those use to four-strokes but once it is familiar you hardly notice this any longer. For sure you don't want to go softening the suspension to try and get rid of this feeling, as it doesn't go away, the bike just starts handling worse.

The rider compartment of the YZ250 is about as standard and fitting as any bike today. Every rider who hopped on the YZ250 felt comfortable and aside from lever position changes did not want to touch a thing. It is thin (especially when looking at it compared to a YZ four-stroke) and the gripper material seat and it's foam excellent. The wider footpegs didn’t draw comments, they are just normal now.

Maintenance on the YZ is as simple as air filter cleanings and transmission fluid changes as needed. The top end life is very dependent on how hard the rider is on the bike but we've known pros to easily get 50 hours on a piston and rings. The top end is simple to work on and it isn't a mystery of which parts need to be replaced.

Conclusion

• An excellent stock package that needs nothing but some mixed gas to go and hit the track.

Though the four-stroke came along and changed everything, taking the bulk if not all of the R&D of manufacturers, the YZ250 is proof that things have not changed all that much. Sure you don't see two-strokes winning at the highest level in motocross, but no one is really even trying to win there. This Yamaha is one of the best packaged motocross bikes you can buy and keeps the sport at an affordable and fun level for the recreational level rider, no matter the speed at which you ride at. It works as well as bikes that cost 1/3 more and really all that is new with this bike is the way it looks. Proven versatile, the YZ250 will easily transition into a trail bike with a spark arrestor slipped on and is a larger gas tank away for longer distance off-road racing. It The YZ is known to be as tough as a rock. Plus for a chassis that has not changed for 10-years, it really doesn't handle all that bad. If fact we think it is excellent. If you don't mind mixing your gas and making funny two-stroke sounds on the track compared to everyone else, it might just be the smartest bike choice you can make.