While everyone was so focused on the radical new YZ450F
, Yamaha went quietly to task making its 250 a better machine. The Tuning Fork designers focused mostly on the chassis this year with a completely new aluminum bilateral-beam design that had us excited during the First Ride
at Washougal Motocross Park. Small tweaks to the motor and suspension keep the rest of the bike in tune with the modern chassis. The YZ-F was a riot in the Northwest, but it wasn’t until we were able to get more riders, varying test conditions and back-to-back comparisons that we realized it wasn’t enough to topple the heap.
The YZ250F has grunt to get over obstacles immediately after corners, but it just doesn't have the legs to run with the other bikes.
For a bike that created this whole 250 4-stroke concept, the engine has become Yamaha’s biggest complaint. A straighter air intake provides better air/fuel delivery and its exit has greater velocity with a new “D-shape” exhaust port which cleans up the bottom end. Our testers were all very appreciative of the five-valve engine’s low-rpm performance, but that’s about all they were thankful for. During our first encounter with the YZ-F, we thought it has a little better over-rev than the old model, but it doesn’t matter because compared to the rest of the 2010 class it has none.
“Bottom-end is stout,” says MotoUSA’s Adam Waheed, “but as soon as you pile on revs the bike feels like it can’t get out of its own way. You’ll be riding it with the throttle pinned and wonder why it’s not accelerating.”
YZ250F Jetting Specs:
Clip Position: 4
Fuel Screw: 2.25 turns
Having a lackluster motor has been the problem with Yamaha’s YZ250F for years. Now that the bike has a bi-lateral beam chassis, expect to see fuel injection come into the mix and hopefully a redesigned engine for 2011. As for this year’s model, an aftermarket pipe would be a good place to start. There were no complaints about the bike down low, so finding a system that accentuates the midrange, and especially the anemic top end would instantly make this a better powerplant and more effective track weapon. The stock muffler is 50mm longer this year and has a smaller diameter core which aid in the 96-decibel output. We also noted a bog from the engine on jump landings. Riders who want to pound through the gears and grunt their way out of turns will find plenty to like about the Yammie, but it’s the least racy engine of the group.
Our WMA pro admitted the top-end weakness, but she found that the extra low-end boost allowed her to carry a gear higher in many corners and with less clutch work than the others.
We loved the Yammie's Kayaba suspension.
A big change in the chassis was reason for concern regarding the suspension. Yamaha had the sticks perfectly matched to the old frame, so it was our hope that they would pick up where the previous model left off without taking any steps backward. Fortunately, Yamaha still has its heavenly suspension - this bike absolutely devours braking bumps! Plush, controlled, forgiving, progressive – the Kayaba speed-sensitive fork and updated shock have it all. Two of our testers ranked the YZ-F suspension best, and not a single one put it at the bottom. There aren’t many updates with the fork, but it does get new surface treatment on the piston rods and redesigned oil seals. The shock spring is 30mm lower for ’10 with revised internal settings.
Tod Sciacqua is one of our faster pilots, and one of the heaviest at 170 pounds. He was one of the few who didn’t rave about the YZ’s Kayaba setup. Stiffer springs would have helped eliminate the sluggish wallowing sensation. However, he was definitely the minority, with most riders satisfied.
Our Vet Expert, Sciacqua, did appreciate the Yamaha’s rock-solid stability, however, and its refusal to get unsettled. Testers in the past have noted the YZ-F line feels long and low, an important component in the renowned Yamaha stability. The new chassis changes makes the 250F feel much more similar to the Honda and Kawasaki machines yet manages to retain that unwavering composure. Weight centralization is improved this year and the center of gravity is lower, both of which give the YZ250F a quicker reaction time – not to mention the lightest curb weight. The steering
Armstrong was happy to attack ruts with the Yamaha's scalpel-like precision.
head is 12mm lower and 7mm rearwards which pushed the radiators back as well. Having the main chassis spars split apart from one another allows a new fuel tank to drop down between them and also sits closer to the center of the machine. More emphasis on the front end makes for better feedback to the riders, all of whom were without complaint on the way it carried itself through the tightest turns, roughest sweepers and biggest jumps.
“I was pretty impressed with the Yamaha’s handling,” says Matt Armstrong, who is a better weight target for the YZ-F at 155 pounds. “It was very precise, especially with all of the ruts on the Piru track. You had to pick a line fast, and it was easy to put the bike where you wanted to.”
Though all the bikes share final gearing within a single sprocket tooth, the Yamaha received compliments for versatility in its transmission. The motor runs out of steam quickly, but the tranny actually helps allow the YZ-F to be ridden in a wider variety of racetracks. Internal transmission ratios for third and fourth gear are taller this year, equating to roughly half a tooth at the rear sprocket according to Yamaha brass. We were happy with its middle-of-the-road characteristic, but changing that gearing is one way to cheat the YZ-F’s lack of top end, and much cheaper than a full exhaust system or motor modifications.
Ergonomics on the new chassis and bodywork were a welcome change.
Speaking of variety, the four-position handlebar mounts add extra appeal to the cockpit, which already is one of the bike’s strong points. The rider triangle suited everyone from our shortest to tallest, though most noted that the YZ has a more compact feel than last year’s model. The seat/tank junction is flat and comfortable, making it easy to move around and take advantage of the excellent handling characteristics. Our blue bike also had the best footpegs, adding to rider comfort, safety and control.
From the moment it was unveiled, the new bodywork and styling cues were hotly contested. Similar to the KTM in this respect, the angular design draws a love/hate response and our crew was not immune. One rider hated it for its “Euro” look while another embraced it as futuristic – take your pick. The white/red limited edition plastic is generally more appealing, but it comes with an extra $100 pricetag.
Stock Fork Settings:
Spring: 4.4 N/mm
H. Comp: 1.75
L. Comp: 9
Spring: 52 N/mm
Race Sag: 100mm
The bottom line is Yamaha makes a very good motorcycle, but its engine doesn’t suit high-level racers in stock form. Excellent bottom and mid-range delivery are ideal for tight, jumpy tracks or riders who like to short shift, but at bigger tracks like Glen Helen and Racetown 395, the Yamaha’s weakness was as painfully exposed as a compound fracture. New ergonomics fit our range of riders despite being more compact than the older version, and the handling is a newfound strength. It’s still a bike that can be ridden hard for a long time, but it also has to be if the rider wants to get anywhere. This is a class where horsepower and usability matter, and the Yamaha comes up short despite being better than it was in 2009.