Compression Conundrum

COMPRESSION CONUNDRUM

CW COMPARISON

WHAT IS THE ULTIMATE RECIPE FOR OFF-ROAD POWER, TWO-STROKE OR FOUR-STROKE?

Brendan Lutes

There are fundamental traits to off-road riding that make it so much fun, like the varying terrain, unique forms of competition, and the numerous types of dirt bikes available. For years, Yamaha has placed a heavy focus on motocross; however, 2016 marks a change, as the Blue Crew has released a pair of hard-core enduro machines: the four-stroke 450FX model and two-stroke 250X.

Both bikes are modeled after their motocross brethren and at first glance look strikingly similar. When you dig deeper, though, you’ll find that the 450FX and 250X are actually purpose-built for the rigors of off-road riding. Each machine features revised suspension settings, an 18-inch rear wheel, a wideratio transmission, and engine tweaks for off-road riding. But even though both bikes are built for off-road riding rather than the big jumps and crowded tracks of motocross, each machine has its pros and cons, and both have DNA firmly planted in closed-course competition.

UPS

DOWNS

• Finally a purpose-built Yami enduro racer ■ Smooth powerequals good traction ■Very stable chassis

■ A lot heavierthan two-stroke ■ More expensive to maintain • Not as flickable

■ Ultra lightweight ■ Snappy handling ■ Inexpensive top end rebuilds

•Tail happy when grip is low • Lacks some high-speed stability • Power isn't as broad

YAMAHA YZ450FX

$8890

YAMAHA YZ250X

$7390

The 250X will bring a smile to just about anyone’s face, while the 450FX is more of a race-ready all-encompassing machine. The two-stroke is light, flickable, and fun to ride. Although the power is broad—thanks in part to the wider gearbox ratios—the 25oX didn’t lose the grunt of the motocross version. The Rayaba “spring” suspension is also excellent for off-road—plush, predictable, and comfortable. Where the 250X lacks, the 450FX clearly pulls ahead, as the bigger four-stroke is much easier to ride in slick conditions and far more stable at speed. Much like the two-stroke, the 45oFX’s suspension is equally as plush and well balanced; however, the power delivery and stability of the four-stroke elevates the bike above the 25oX. It’s difficult to beat a modern four-stroke’s power and reliability. But if you’re looking for a bike that is fun to ride and will get you in and out of anything, the two-stroke is a solid choice too.

Off-road is inherently challenging, and choosing the best weapon for any race, or challenging trail ride with buddies, is always important. Both the YZ450FX and YZ250F have their advantages and shortcomings. The 25oX is best suited for tight, technical terrain where throwing around a light bike is a necessity.

The 450FX is an excellent all-around machine that handles the rigors of offroad extremely well and puts the power to the ground in an efficient and controlled manner. Choosing one before the other is a tall order, so suffice it to say, for now we’ll just keep both of them in our stable—mainly because we can.