Yamaha's 2009 YZ250 and YZ125 bike intro was not really to show off the bikes' minimal changes, but to remind us how fun these bikes are. They gassed up their '09 two-strokes and sent us out on a 'Field of Dreams'-like private track to twist throttles and stretch smiles. This has to go down in history as the most successful bike intro ever based on a manufacturer reaching its goals. These pingers are loads of fun, and if you've been on a straight-gas diet for too long, you probably forgot the incredible response of the YZ250 (you don't need a fuel injection system to spike your adrenalin) or the magical handling of the YZ125.
The changes are hardly worth mentioning: a switch from the Dunlop 739 front tire to the Dunlop 742FA (actually, that's worth a mention), a switch on the YZ125 to the 200-gram lighter Dunlop 756G rear tire (from the 756), an aluminum front brake hose holder 2008 model was steel), a DID gold chain, and a new seat cover. What is significant is that the bikes are here at all. Yamaha is the lone Japanese manufacturer who still believes in their two-strokes. They should, they seemed to have hit their development process perfectly, getting the bikes to a level of performance that leaves little room for improvement... seemingly. Who knows where these bikes could go if they got some R&D dollars. But right now the smokers are just fighting to stay alive. Yamaha wants to keep producing and importing these bikes, but business usually comes before passion in a big corporation, so the future of these amazing bikes is in your hands more than in the hands of the brass at Yamaha.
The YZ doesn't lay over for 450s, but it does lay over for juicy berms
The competition these bikes face on the tracks is from the equivalent displacement (and cheater 150) KTM models, but the competition they face on the showroom is from all the shiny new 250cc and 450cc four-strokes that are getting all the development as well as marketing attention. The modern four-stroke race bikes are incredible, and likely offer better lap times than these pingers, but there are lot the mixed-gas racers still do better.
Dropping in: A two-stroke's lower center of gravity (and no high-CG gyroscopic effect of cams and a cam chain) makes them feathery to lay over into a rut compared to their four-stroke counterparts.
Laying over under power: The same reasons they lay over easier gives them less tendency to want to stand up once on the gas in a turn.
Throttle response: EFI 450s are getting there, but the direct connection your right wrist has to an arsenal of ready-to-charge horsepower on the two-stroke is still unmatched.
Remember the feeling? When was the last time you flew a two-stroke?
Weight feel: The bikes weigh less than their four-stroke competitors, but not significantly so. The feeling once on the track, however, makes the difference dramatic. Two-strokes are light on their feet. The YZ125, specifically, feels lighter than you can imagine a full race bike ever could. And the low-weight feel makes these bikes a blast to ride as well as less tiring - so you're having more fun, for longer. How's that for squeezing the most out of your track entry fee?
More powerful power: The power is fast and abrupt on these bikes. The YZ250 is no bike for a beginner rider. You need to have good throttle control and a good dose of humility before you climb on the YZ250, because there is no hesitation when you throw the corral gate open and let the horses out.
Flickability / flight time: The smokers' light feeling translates into more bike control when airborne. If you're ever going to whip a bike, it'll be one of these.
Mud: Two-strokes seem to repel mud packing onto the bikes better to better keep their light feeling when the four-strokes are packing on mud mass to their already-heavier feel.
The 125 is super agile going into corners and still has the power to make coming out of them a blast.
Rev without guilt: Hitting the rev limiter on a two-stroke just means reaching the rpm where the power tapers off (sometimes pretty rapidly). There's no catastrophic engine failure in your future if you like to scream your bike around the track. 250F's won't last too long at the rev limiter, and with 450 four-strokes, the rider probably won't last too long with those powerful engines at full steam.
Starting: No starting drill, no need to find neutral when the bike's hot - just kick it and go.
Maintenance: The YZ are reliable bikes, but all bikes require routine maintenance. Four-strokes are more intimidating than they are complicated, and there's no reason to fear them, but a simple two-stroke motor makes the learning curve much more gradual for new riders, and makes work much quicker for experienced wrenches. It's a topic of debate, but generally two-strokes are cheaper to maintain than four-strokes.
Drive train wear: You chain and sprockets will last longer without the pull of four-stroke torque.
But if you really want to move dirt, the 250's crisp throttle is connected to a lot of responsive horsepower.
Teacher: Two-strokes require more precise gear selection. You will be shifting these YZs much more frequently than their four-stroke competition. This is good for developing riding skill, and also a lot of fun. Some people love the 'one gear for the whole track' of the 450s. Those people won't appreciate grabbing gears as fast as your left foot and left hand can manage on the YZ. It's a thrill. Riding a slower bike close to its potential is more rewarding than riding a more powerful bike at a fraction of its.
Hey! What's with the love letter to the YZs? If two-strokes are so superior, why are the four-strokes taking over?