2015 Yamaha YZ250FX

Introduction

• Yamaha's stab at KTM's competition off-road dominance of late.
• Refreshing to see Yamaha back in the game, properly.
• Did Yamaha mix the ingredients correctly?

As new as this Yamaha YZ250FX may seem in concept, Yamaha has been mixing the lines between the Motocross and Off-Road in a competition-only form going back as early as the 1970s. Even before the riding time of many reading this test, remember the IT?. But lately that in-between bike did not exist in the company’s lineup, it was YZ or WR or nothing. And getting that hybrid, a mostly motocross bike with an electric-starter, six-speed transmission, 18-inch rear wheel was basically impossible unless you went and simply bought a KTM or got close by building one yourself. The starting grids at events such as the GNCC series displayed this trend no matter how well Yamaha racers did on converted YZ machinery. Luckily a very motivated group of project engineers in Japan have a thing for this off-road segment. Because of this, talks began early on with regard to using the 250cc YZF platform to create the YZFX off-road racer.

Changes

• All-new and based off the YZ250F.
• Motocross performance with off-road essentials, and not too many of them.

The FX is an all-new machine but takes heavily from the YZ250F that was so spectacular last year (Click here for a link to the test). But from a performance view there are quite a few very specific similarities with the YZ250F and then necessary differences. The architecture is all YZ including the rearward exiting exhaust, the air-box atop the engine and the frame’s geometry and the components attached. The frame is identical to the WR250F and does differ in some mounting tabs, as in skid plate tabs (which is not standard) and some of the electronics, the bigger changes are in small details like the thinner engine mounts to allow more flex. Suspension components are the same as YZF, except for the lighter spring rate on the fork and altered internal valving set specifically for off-road riding/racing.

The engine, from the power producing side of things is identical to the YZ250F from the forward mounted 44mm throttle body to the end of the competition-only muffler. The cam timing and profile is claimed to be identical with the only difference being an altered decompression ramp on the exhaust cam to accompany the electric starting. The changes in the transmission are substantial with a six-speed wide-ratio tranny. First gear is lower than the YZs and sixth a jump over the YZs fifth. The engine has electric-starting with a kick-start backup. The charging system has to been boosted to a 160-watt alternator with added flywheel mass as well. Changes to the clutch include a different pull ratio, lighter springs, different oiling holes and a different material on the friction plates.

Off-road features include a 18-inch rear wheel and kickstand. Since the bike is full-competition, the GYTR Power Tuner can be attached and ignition and fuel maps can be altered and tuned. Note, there is no spark-arrestor in the muffler, yet there is the plug to easily attach the radiator cooling fan if a rider wants to upgrade.

Power

• A traction grabbing 250F motor that has throttle to rear wheel connectivity.
• Makes power all the way through the RPM range.
• Spot-on FI mapping.
• A little loud for our off-road ears.

The YZFX has a power delivery of its own and a very good cross of YZ aggression and WR rideability.  The electric starting is great and the bike fires right up even on cold mornings only needing choke on the coldest. It settles down to a nice idle and the sound of the muffler is a little on the loud side for an off-road machine, yet understand this is a pure moto muffler. The throttle response is crisp and there is even get a little noise out of the airbox, a snarl sound when the cams really start to function.

The good thing about this motor is that first gear’s internal ratio is lower than the YZF for tighter riding and less clutch abuse. Second is just a little lower than the YZF as well and third is nearly identical, meaning the second to third jump is a little more than the YZF. But the question is, can you feel it? Not really, as the FX is tuned a little more for torque and rideability so this plays more into the pick-up than the gear spacing. Where the FX has bigger gaps (and an extra gear) compared to the YZF, in real riding conditions the FX uses the gears longer than a YZ, which makes shifting less critical, less often. We did not have any issues with the gaps being too large, even with heavier riders and a change to a larger rear sprocket could erase any issues easily and you’d still have a longer spread than a YZF. And we saw a solid 89 MPH GPS indicated on the FX with stock gearing, which is mighty fast for a 250cc anything! The clutch pull is light and the engagement a little on the soft side not a lot of initial bite, but not many complained.

On the very bottom FX is a typical 250F in that it is easy to stall if the throttle is closed. The added flywheel weight helps as much as possible without making the bike feel too sluggish. The power builds and builds in a pretty linear pull and can really scream out to the near 13,000 RPM rev limiter, which is hard to hit without being abusive. Compared to a YZ the snap on the bottom (lower mid-range, which very few few will ride this bike in the lower 1/3 of the RPM range) is a little softer than the YZF and the R’s don’t build as quick. Compared to the WR250F the FX is very responsive and makes the EPA setting feel very sleepy and very lean. Once in the meat of the power it is difficult to distinguish between YZF and FX other than the FX revs up a little slower and isn’t so quick to hit the rev cut nor does it feel like it tapers off in power as abruptly.

We mounted an FMF Hex Q4 to hit the trails and it did as expected. It quieted up the sound level a significant amount and slowed the surge of power and the build of the RPM. For trail riding, it was an improvement at a more relaxed pace. We’re pretty sure we could bring back some of the response with the use of the GYTR tuner which we will test later since the bike is so spot-on with the stock open exhaust.

No matter what, the FX is a very powerful 250F that is easy to ride and has get-up-and-go. It always wants to pick up as the throttle response and FI settings are spot-on, no matter the altitude. We ride it at 7500 feet and for sure you could feel the reduction in power but the mapping was spot on.

Suspension

• The right mix of stiffness to hold it up and plushness to tame the MX chassis.
• Great bottoming resistance even for big guys.
• Adjustable to perfection with the clickers--and not too far off stock. It is a do-all for most riders.

Equipped with the same suspension that is on the YZF, (KYB SSS spring fork) the quality of the components is capable of doing pretty much anything. Set up with a one-step lighter fork spring on the front and the same spring rate on the rear when compared to the YZF, Yamaha was looking for that off-road compliance with race stiffness. In appeared to us the FX seems set up for a rider in the 170-lb. range but easily handled our heavier riders just fine off-road where it does what it should. It holds the bike up in the stroke without being too rigid in the initial part of the stroke. It also has really good bottoming resistance. It is the kind of bike that can be ridden fast without worrying about the suspension holding you back.

On the motocross track it also performs well, although not as firm as a pure MX bike. It absorbs a lot more of the ripples, bumps and jars the rider a lot less. It will uses more of the stroke on the jump faces and less smooth on landings. For a fast rider or heavier rider, this is a little bit of a problem though adding compression to the fork and the shock can go a long way holding the bike up more. But it is a tradeoff in bump compliance. We would call it a track day bike more than a motocross racer. But as a mix for doing off-road racing and having the ability to tackle the track, the Yamaha is one of the best compromises we've sampled.

Chassis - Handling

• A very balanced package, even more endearing than the praised motocrosser.
• The power and the handling work hand-in-hand.
• A lot lighter than it looks or what you'll see on a scale.

One thing you have to get use to is the appearance looking at the front of the YZFX where the radiator shrouds are, it appears wide. So some assumed it was heavy, till they rode it. Being a 250F and weighing in at 247.5 pounds with a full tank of gas, the scale is not the best selling point for the FX. But if you just rode it and never put it on the scale, you’d never suspect it weighted that much. It has a very agile handling feel that could be described as light on its wheels. The power helps this, the suspension compliments this and the bike really works as a whole.

The motocross YZF has more of a front steering character where most riders felt the FX was more balanced. It turns very predictably and when you get your weight forward it really sticks. The Dunlop MX81 front tire is a good match in all of the different conditions we rode on. The rear tire was a little less grippy but that showed the FX could slide as well as it would track, there is very good connectivity between the throttle and the rear wheel. Jumping the FX isn’t the lightest feeling once in the air but it isn’t anything to be concerned with. We ran our testbike with roughly 110mm of rear shock sag with the rider aboard. And where the WR acted a little unstable, the FX had a lot less of this trait, we credit the boosted power in the mid for keeping the FX more active and stable at the same time.

Like the WR, the FX isn’t the roomiest with the handlebar in the stock position, but moving them to the forward mount in the adjustable top clamp, opens up the riding cockpit. Getting to the gas cap in a quick manner is tough with the stock setup, though there are aftermarket options out there. And if needing more than two-gallons is an issue, you'll need that aftermarket help. We rode into the high 60-mile range on a spirited desert trail ride. We could see it running out in the 30-mile range in racing conditions, estimating just over an hour of racing at most. Some testers felt the Yamaha levers have a dated feel in the bend even though the clutch has a quick adjust. Handguards would be a nice bonus too. The brakes are very average, which is great these days. They offer plenty of feel and are not grabby at all even after one of our brake dragging testers gave it his best shot at overheating them.

Conclusion

• Yamaha nailed it with this bike. It is the do-all off-road concept in 250cc four-stroke form.
• The added value of FX, electric starting and six-speeds are well worth the price increase over YZ.
• Is there a 450cc or a two-stroke FX in the near future? We can only hope.

There is no denying what the target market for this bike is. It will compete side by side and share the market KTM has taken with the XC line. A motocross bike with a few off-road necessities that are difficult for the regular guy to adapt or modify. Exactly what Yamaha has done with the FX. And we know how good the motocross bike they started with is. So that leaves the simple question of how good is the Yamaha, really?

The YZ250FX is an excellent machine in everything we used it for. It is ready to race off the showroom floor at a GP, GNCC or Hare Scramble type event. It is an unintimidating motocross bike for the novice or the track day rider and with a noise compliant spark arrestor it is a great aggressive trail machine. Yamaha is well known for its durability and in the 20 hours we've put on the bike in testing, we did little more than change the oil and clean the air filter. The air filter does not stay as clean as you would suspect being in such a high location, yet if you ride in roost and dust, the smallish element will beg for a cleaning. We think the skid-plate mounting tabs on the front of the bike look a little naked just hanging there and the electrics housed where an air box is normally located would usually be get covered with mud in sloppy conditions but nothing bad happened. The oil capacity is roughly 850cc and Yamaha recommends changing it every 7.5 hours which should get you through most races easily.

We’re sure the bigger question is whether or not it is better than the KTM, but the only way to test that is to get them out together to compare. But we will tell you that you can’t really go wrong with Blue.