by Jody Weisel on 07/27/2010
Q: FIRST AND FOREMOST, IS THE 2010 YAMAHA YZ250 BETTER THAN THE 2009 YZ250?
A: No. It is identical to last year’s model. Well, not identical, because there were two changes from 2009 to 2010:
(1) The right-side gas tank graphics are new.
(2) The left-side gas tank graphics are new.
Q: HOW CAN YAMAHA GET AWAY WITH NOT MAKING ANY CHANGES TO THE 2010 YZ250?
A: They can “get away” with not changing the 2010 YZ250 because it is as close to perfect as a showroom stock motorcycle can get.
Q: COULD YAMAHA’S ENGINEERS MAKE THE 2010 YZ250 BETTER?
A: Yes, they could. Every manufacturer could make their bikes better if they had the budget. But, and this is a big but, the budget for any given model is determined by “return on investment.” Before investing a million dollars into more horsepower, sleeker ergos or whiz-bang gizmos, the bean counters have to determine whether the costs of development will be offset by an increase in sales.
Unfortunately, the current market doesn’t look good when it comes to return on investment—and the return on two-strokes is even less than on the poor-selling four-strokes. Thus, Yamaha decided to stand pat on the 2010 YZ250.
Q: WHAT CHANGES WOULD WE LIKE TO SEE YAMAHA MAKE TO THE YZ250 TWO-STROKE?
A: Here is the short list:
(1) Horsepower. The YZ250 has good power and a sweet two-stroke powerband, but it isn’t the most powerful 250 two-stroke sold. If the YZ250 had KTM’s 49 horsepower with the YZ’s powerband, it would be a missile.
(2) Weight. It’s not heavy, but it could be lighter. The AMA allows a 250 two-stroke to weigh 212 pounds (a 450 four-stroke has a 220-pound minimum limit). On the showroom floor, the YZ250 could easily be 5 pounds lighter.
(3) Cosmetics. As new models come out, the tastes of the riders change. Bikes designed in the last couple years are flatter, sharper and more modern looking. The YZ250, which hasn’t seen a major change since 2006, looks rounder. It’s
(4) Suspension. We have no complaints about the performance of the YZ250’s Kayaba SSS suspension. It is sweet. But, and you knew a but was coming, the YZ250 still uses the old-style shock linkage (that is mounted through the swingarm instead of slung under it).
(5) Accouterments. A handful of the parts on the YZ250 are old-school. For example, the YZ-F bikes have 25mm rear axles. The YZ250 still has the older model 22mm axles. We’d like it to get the new swingarm, shock linkage, triple clamps, rear hub, clutch lever and zinc-coated chain.
Q: WHAT ARE THE BIG PLUSES OF THE 2010 YAMAHA YZ250?
A: Here is where a YZ250 two-stroke shines.
(1) Price. The retail price of a 2010 Yamaha YZ250 is $6999. The 2010 YZ450F costs $7990. The YZ250 retails for a grand less than its 450 brethren.
(2) Maintenance cost. To rebuild a YZ250, all it requires are a piston, rings and gaskets. The top-end kit (piston, rings, circlips and wrist pin) retails for less than $175. The same parts for a YZ450F (piston, rings, circlips and wrist pin) run over $250. And it should be noted that rarely will you be able to get away with just changing a four-stroke piston without checking the valves, valve seals, valve springs, keepers and cam chain.
(3) Titanium shock spring. Yamaha removed the Ti shock spring from its four-stroke line, but the YZ250 has a titanium shock spring. It would cost $600 to buy this spring from your dealer.
(4) Weight. No contest. A YZ250 comes in 12 pounds lighter than a YZ450F.
(5) Line choice. The snappy power of the two-stroke has more of a tendency to lift the front wheel, break traction and spin the rear tire. As a result, the bike turns from the rear. It likes to powerslide and explode out of turns. In soft dirt, whoops and loam, the two-stroke gets on top of the dirt much quicker than a four-stroke. It’s more willing to make quick direction changes and switch lines on a whim. YZ250 two-stroke riders are rewarded for seeking out good dirt and taking the bull by the horns. The power delivery of the two-stroke makes it feel even lighter than it is.
(6) Fun factor. We hate to say it, but the difference between racing a four-stroke and a two-stroke is night and day. A two-stroke wheelies, spins, roosts and rockets around the track—even if you’re going slow. A four-stroke drones around the track and feels more like driving a car than a classic dirt bike. Two-strokes are fun to ride at any speed.
Q: HOW DOES THE YZ250 TWO-STROKE COMPARE TO THE YZ250F FOUR-STROKE?
A: No contest. In most amateur racing organizations, a 250cc two-stroke is legal in the 250 four-stroke class. When compared to a 250 four-stroke, the YZ250 makes nine horsepower more than a 250cc four-stroke—it is does it with one-third the moving parts. swing radically in favor of the 250cc two-stroke.
(1) Power. The YZ250 two-stroke makes 45.5 horse-power, while the YZ250F only produces 36.3 horsepower. That is a nine horsepower advantage for the 250 two-stroke.
(2) Lap times. In back-to-back testing, the MXA wrecking crew discovered that, on average, lap times were identical between a YZ250 two-stroke and YZ250F four-stroke. Logic says since lap times are virtually identical, the man who gets to the first turn first should win. With a nine horsepower headstart, if a 250cc two-stroke doesn’t beat a 250cc four-stroke to the first turn, the rider needs to work on his technique.
Q: IS THE 2010 YZ250 FASTER THAN A 2010 YZ450F?
A: No. Of course not. Simple logic will clue you in to the fact that a 450cc engine makes more power than a 250cc engine. What is surprising is that the power difference isn’t greater. The YZ250 makes 45.5 horse-power, while the 80-percent-larger YZ450F makes 52.6 horsepower. That is actually a smaller advantage for the YZ450F over the YZ250 than the YZ250 holds over the
YZ250F (9 horsepower to 7 horsepower).
On sheer numbers alone, the YZ450F will be faster than the YZ250.
Q: HOW DOES THE YAMAHA YZ250 HANDLE?
A: Most MXA test riders describe the Yamaha YZ250 as a stable platform machine. What is a stable platform machine? It is a chassis that doesn’t get in the way of the rider. Unlike a Suzuki, which focuses most of its energy into turning, or a Honda, which dances on a fine line between oversteer and understeer, the YZ250 two-stroke is neutral. Neutral means that you can make it oversteer or understeer by how much input you put into the chassis. It is accurate at turn-in, requires no mid-turn corrections
and self-steers from the center out.
Don’t misread us. The YZ250 isn’t the best handling bike on the track. It is middle of the road at best. But when you combine the “rear-steering” nature of a two-stroke with light weight and snappy power, you get a go-where-you-point it machine.
Q: WHAT DO YOU NEED TO DO TO RACE THIS BIKE OFF THE SHOWROOM FLOOR?
A: Not a thing. You could plop down cold hard cash at 8 in the morning and be racing it at 10 a.m. This baby is race-ready.
Q: WHAT ARE THE BEST MODS FOR THE 2010 YZ250?
A: Here are the top three:
(1) Reeds. MXA test riders choose the Moto Tassinari VForce3 to replace the stock YZ250 reed cage. The Moto Tassinari reed is a simple modification and makes a noticeable difference in the power. Moto Tassinari’s phone number is (603) 298-6646.
(2) Gearing. We also add one tooth to the rear sprocket of the YZ250. Why? Because most MXA test riders want to get into third gear sooner, and the lower gearing punches up the acceleration in second gear (which brings third into play sooner). No matter what anyone thinks, showroom stock bikes are geared for racing—they are geared for general all-around use. Faster riders, featherweight riders and fast tracks work best with the stock gearing.
(3) Exhaust pipe. Two-strokes love expansion chambers, and the YZ250 is no exception. You can get two extra ponies out of the YZ250 with an aftermarket pipe. We typically choose to run a Pro Circuit pipe and silencer because that is what Chad Reed used on his works YZ250.
Q: HOW IS THE STOCK JETTING?
A: Since engine R&D was frozen in place five years ago (2006), Yamaha has had a long development period to iron out the kinks.
MXA’s recommended jetting is as follows:
Pilot jet: 50
Clip: 2nd from top
Air screw: 3/4 turns out (1 turn stock)
Notes: The air screw is very sensitive from 1/2 turn to one turn out. In practice, it doesn’t seem to be as critical after one turn out. If you switch to an aftermarket pipe, you should go up one on the mainjet.
Q: HOW GOOD ARE YAMAHA’S KAYABA SSS FORKS?
A: Awesome. Yamaha has the best showroom forks, because Yamaha engineers decided to turn the age-old position-sensitive damping concept on its head and make their SSS forks 90-percent speed sensitive. Speed-sensitive damping determines damping resistance based on the speed at which the piston moves, not its position in the stroke.
Q: WHAT WERE OUR BEST FORK SETTING?
A: For hardcore racing, these are MXA’s recommended 2010 Yamaha YZ250 fork settings:
Spring rate: 0.43 kg/mm
Oil height: 130mm
Compression: 13 clicks out
Rebound: 14 clicks out
Fork leg height: 5mm up
Notes: On Yamaha’s SSS forks, there is some crossover between the rebound damping and compression damping, which means that turning the rebound in will not only make the forks slower on rebound, but stiffer in compression.
Q: WHAT ABOUT THE REAR SUSPENSION?
A: This is a works shock. It comes with a jumbo-sized 18mm shock shaft, Kashima-coated internals, and a titanium shock spring. This is cool (and something that no other production bike can claim). For hardcore racing, these are MXA’s recommended 2010 Yamaha YZ250 settings:
Spring rate: 4.9 kg/mm
Race sag: 100mm
Hi-compression: 1-3/4 turns out (1-1/2 stock)
Lo-compression: 8 clicks out
Rebound: 8 clicks out
Notes: Yamaha’s high-speed compression clicker (the large dial) is very sensitive to adjustment. Make small (1/8-turn) changes. Use the high-speed adjuster to set the bike’s fore/aft bias at speed.
National speed riders and heavyweight contenders will need to move up to a 5.0 kg/mm spring.
Q: WHAT DID WE HATE?
A: The hate list:
(1) Updates. We don’t like the idea that the four-strokes get a zillion little updates every year that improve the bikes
in small ways while the YZ250 gets left out.
Q: WHAT DID WE LIKE?
A: The like list:
(1) Ti shock spring. Cool. Very cool.
(2) Frame. The hollowed-out cavities of the YZ250 aluminum frame look cool. Why did Yamaha go away from them on the four-strokes? They didn’t; they just turned them inside-out.
(3) Suspension. You gotta love Yamaha’s SSS suspension—unless you own a suspension shop.
(4) Reliability. The YZ250 could blow up four times before you’d spend as much money as one explosion would cost on a four-stroke. Plus, even if you are the worst mechanic in the world, you could rebuild the YZ250 by yourself with a butter knife and a nut cracker.
Q: WHAT DO WE REALLY THINK?
A: If you aren’t a future AMA Pro racer or a local guy who has a 35-race win streak, you really should be on a Yamaha YZ250. Why? Where should we start?
(1) It weighs 12 pounds less.
(2) It makes more horsepower per cubic centimeter than any four-stroke on the planet.
(3) It starts on the first kick.
(4) It can be rebuilt for lunch money.
(5) It has one-tenth the moving parts of a four-stroke.
(6) It never stalls in a corner.
(7) It sells brand-new for $1000 less than a four-stroke.
(8) You can work on it yourself.
(9) It is the most fun you can have on a motorcycle.
(10) Do you really need another reason?
This entire article was retyped here from a Motocross Action Magazine Test. Please support those who support two-strokes and subscribe to this fantastic magazine.