2015 Yamaha YZ250F First Ride Review

Scott Rousseau
by Scott Rousseau

Minor tweaks yield major improvements

It’s safe to say that Yamaha came about as close as a manufacturer can to setting the motocross world on fire with the YZ250F in 2014. Borrowing heavily from the architecture of its revolutionary YZ450F, the company’s all-new quarter-liter contender broke cover with a new, fuel-injected, rearward-inclined engine that places the straight downdraft intake out front and the exhaust in the rear. In addition to the new cylinder head’s symmetrical port design, which allowed Yamaha engineers to extract a lot more power from the engine, the compact engine allowed Yamaha to centralize the 250F’s mass in an all-new compact bi-lateral beam chassis that is shared with the YZ450F.

2015 Yamaha YZ250F

Editor Score: 95.0%
Engine 19.0/20
Suspension/Handling 15.0/15
Transmission/Clutch 9.0/10
Brakes 8.0/10
Ergonomics/Comfort 10.0/10
Appearance/Quality 10.0/10
Desirability 10.0/10
Value 9.0/10
Overall Score95/100

Still, savvy motoheads might beg the question that if all of the technology from the YZ250F was effectively handed down from its big sister, how is it that the 250F dominates its class where the 450F has pretty much failed to do so? There are a lot of ways to answer that question, and most of the debate would likely revolve around power management and, by extension, handling, when dealing with a high-steroid 450cc four-stroke single.

Yamaha invited us to Southern California’s Glen Helen Raceway to sample the 2015 YZ250F. Already the class leader, the 250F benefits from minor tweaks that add up to significant improvements over the revolutionary 2014 model.

All we do know for sure is that the same radical changes that Yamaha brought to the YZ250F obsoleted the previous model and turned the new bike into a winner right out of the crate. The new design has already proven itself with multiple wins by factory-backed Yamaha riders Jeremy Martin and Cooper Webb in the 2015 Lucas Oil 250cc Pro Motocross Championship, where Martin is the current class points leader.

With a total revamp of the YZ250F already accomplished, Yamaha’s approach for 2015 was merely to improve on the existing design by addressing a few details – call it evolution of a revolution – and the company graciously invited us out to Southern California’s Glen Helen Raceway to sample the new machine for ourselves. We loved last year’s bike, but this year’s is even better.

249cc engine features a 6.2-degree rearward slanted cylinder and reverse cylinder head configuration with a straight downdraft intake and symmetrical ports. The combination yields a compact powerhouse that centralizes the engine’s mass in the chassis. Yamaha has revised the exhaust cam to make the ’15 model much easier to start.

If you read our review of the 2014 YZ250F in Alabama, you know that 2014 could be a cantankerous starter when hot, despite its excellent fuel-injection, which uses a single 10-hole injector fed by a fuel pump delivering 47 psi to its 44mm Keihin throttle body. Yamaha engineers have addressed the issue by going to a new exhaust cam that retains the lift and duration of the previous cam but the angle of the auto decompression pin has been altered 6 degrees. The difference is immediately noticeable, as the 2015 is way easier to kickstart, and fires up much more readily, than the 2014.

Once out on the track, another of Yamaha’s changes was immediately noticeable right from the first hit of the throttle: The 2015 YZ250F’s ECU has been recalibrated with new 3D fuel and ignition maps, which are still adjusted based upon gear position. The new maps provide smoother power control at lower rpm. Yamaha claims that they also offer broader mid-range torque and smoother high-rpm overrev, but those changes are less obvious. We can vouch for the 250F’s more linear throttle response off the bottom. The 2014 model felt somewhat choppy in the off-on throttle transition by comparison, but you can practically count each revolution build as you roll on the throttle now. It’s such a difference that some members of other test crews swore that the YZ250F felt like it made more bottom-end power than last year’s bike. Not so, says Yamaha. It just runs cleaner.

One minor change for 2015 is an easier throttle pull, courtesy of a lighter throttle return spring. It wasn’t readily apparent at the track, but it should help to reduce rider fatigue during a long moto.

Internally, the YZ250F’s engine also gets a few minor tweaks for 2015. Its 77.0 x 53.6mm bore and stroke are the same as the 2014 – and the 2013 for that matter – but the 2015 piston’s ring lands have been change to provide better oil control, and the titanium exhaust valves feature a new coating that is more durable than the previous coating. The five-speed transmission’s gear ratios are unchanged, but the gear stop lever has been changed from a ball-bearing-style to a positive roller-style to improve shift quality. The 250F’s power is transmitted through a nine-plate clutch.

And it’s a heck of a lot of power. Yamaha has claimed all along that the engine makes 40 horsepower, and since they let us keep the unit we sampled at Glen Helen, we intend to put that claim to the test on the dyno. But there’s no denying that this is one fast 250cc four-stroke, building fantastic thrust right off the bottom and transitioning into a healthy mid-range and maintaining its brawny feel all the way to the rev limiter. After spending all morning on the Glen Helen track, expert tester Ryan Abbatoye once again proclaimed his admiration for the engine, which delivered enough oomph for him to clear a jump he had previously only been able to clear on a 450cc machine. The biggest difference between the Yamaha and its competition right now is that there are simply no flat spots in the YZF’s powerband, which not only makes it feel fast but also makes it easier to ride by novice and vet riders.

We already knew that the 2014 YZ250F ripped, and the 2015 edition is no different. Ace test rider Ryan Abbatoye put our test bike through its paces at Glen Helen and reported that the 2015 makes all the forward thrust that made the ’14 so awesome, and the revised ECU calibration makes it easier than ever to haul the mail.

As our riding session took place on an open track day at Glen Helen, it didn’t take long before the track was extremely rutted up by the constant pounding of the masses, and that gave us a chance to gauge the new front fork settings that Yamaha has come up with for the YZ250F’s KYB Speed-Sensitive System inverted front fork. The 2015 has been set up with slightly more oil than the 2014, and its compression and rebound settings have been firmed up as well. Our experience on the choppy Glen Helen track led us to reduce the rear sag height and then reduce the compression to bring everything into better balance. After that, we had no complaints with the action of the fork or its fully adjustable KYB rear shock.

We loved the 2014’s slender, aluminum bilateral beam chassis, and the 2015 is identical in every way. It boasts razor-sharp turning manners while remaining straight as a string on rough, high-speed straightaways. Frankly, it’s excellent. Ditto for the YZF’s slim cockpit which features a very flat seat and a recessed fuel cap that allows the rider to really get forward on the machine in the turns (the YZF’s 2.0-gallon fuel tank is located mid-ship in the chassis, under the seat, in keeping with its mass-centralization goals). The handlebar mounts also offer four positions for a total of 36mm of adjustment to accommodate riders of various sizes.

The YZ250F’s slim bilateral beam aluminum chassis gives the bike a light, flickable feel, and it is as stable in the air as it on the ground, which should increase rider confidence at all skill levels.

Some of the other changes that Yamaha called out were either not readily apparent on the track, or they were mostly cosmetic, but they are still appreciated. They include a lighter throttle return spring that is claimed to reduce throttle pull effort by 20 percent. Maintaining the YZ250F’s air filter is now easier than before, as Yamaha has replaced the three 8mm bolts that hold the upper “fuel tank” shroud with Dzus fasteners for completely tool-less removal.

The 2015 features the same 250mm wave rotor front disc and two-piston caliper as the 2014 model. While that is a little bit of surprise since the competition is making the move to an even larger 270mm front rotor, we have no complaints about the Yamaha’s front braking power or feel, and the same goes for the 245mm rear rotor and single-piston caliper out back.

Yamaha continues to resist the air-sprung fork trend in motocross and stick with a proven coil-spring design. The YZ250F’s KYB fork features Speed-Sensitive damping cartridges with revised settings for 2015. Suspension travel is 12.2 inches up front. The fully adjustable KYB piggyback reservoir shock out back provides 12.4 inches of travel.

Lastly, the 2015 YZ250F gets new graphics that are embedded into the radiator shrouds to make them less prone to peeling. The YZ250F remains available in two color schemes as well: Team Yamaha Blue/White, or White and Red. Capping off the styling appointments are a new Gold D.I.D. 520 chain with a coating that makes it more corrosion resistant and black Excel rims, also new.

Best of all, though, is that the changes Yamaha has made to enhance the YZ250F don’t come with an increased MSRP; Yamaha is holding firm with the YZ250F at $7490. That’s a lot of money, but when you consider the technology and performance that Yamaha has poured into the YZ250F, that’s chump change. Last year’s bike was revolutionary. This year’s is evolutionary. Either way, Yamaha’s Japanese and European rivals had better have done their homework if they are going to topple the YZ250F from its perch atop the 250cc motocross class.

Yamaha is the only manufacturer to offer its motocross models in two color choices. The 2015’s optional white/red/black version features more subdued graphics in a color scheme that harkens back to Yamaha’s old European factory racing colors.

2015 Yamaha YZ250F Specs

EngineLiquid-cooled four-stroke single, DOHC four-valve head
Bore x stroke77.0 x 53.6mm
Horsepower40 rwhp (claimed)
Compression ratio13.5:1
Fuel SystemKeihin EFI, 44m throttle body
Final driveChain
Frame typeBilateral beam aluminum
Front suspensionInverted KYB fully adj. fork w/Speed Sensitive System; 12.2 in. of travel
Rear suspensionKYB fully adjustable monoshock w/piggyback reservoir, 50mm piston; 12.4 in. of travel
Front brakeNissin two-piston caliper 250mm wave-style disc
Rear brakeNissin single-piston caliper 245mm wave-style disc
Front tireBridgestone M404-A 80/100-21
Rear tireBridgestone M403 100/90-19
Wheelbase58.1 in.
Seat height38.0 in.
Ground clearance12.8 in.
Wet Weight231 lbs. (claimed)
Fuel capacity2.0 gal.
Color choicesBlue & White / White Red & Black
Scott Rousseau
Scott Rousseau

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  • Old MOron Old MOron on Jul 18, 2014

    Man, this thing looks like fun.
    I sure wish MX didn't didn't require loading up a truck, driving half way across Creation, then driving back. Oh well, supermoto in the local canyons is still fun.

  • Craig Hoffman Craig Hoffman on Jul 18, 2014

    Yamaha finally did a worthwhile update on their WR 450 with a new chassis, FI and much better suspension, but it is time for them to fully bust loose and import this tech into the WR line. KTM has been having all the fun for too long.

    The current WR450 (once the silly restrictions are undone and a proper exhaust is in place) is a snarling beast. A 400cc version of this design in WR form could be a killer off road bike with sweet and potent power and less unruly handling than the full 450. Very well designed "less" may just be more. Back to the future with a backwards engined WR400!