If you are a fan of great moments in historythe Hindenberg explosion, Pearl Harbor, the Beatles at Shea stadium or the opening of Disneyland Paris, you need to pay close attention. Earth-shattering, world-changing and envelope-busting motorcycles are few and far between. They don't happen every day, every year or every decade. If you are lucky enough to be alive, with cash in your jeans and free from worldly constraints when it happens, you get to buy one.
Well, this is your lucky day! The release of the all-new Yamaha YZ450F is the motocross equivalent of the fall of the Berlin Wall or when Steve Jobs met Steve Wozniak. It's gonna change the way you think about the world.
Q: IS THE 2006 YAMAHA YZ450F BETTER THAN THE CRF, KX-F, RM-Z OR SXF?
A: Yes. Unequivocally better.
Q: WHY IS THE YZ450F THE BEST 450 MOTOCROSS BIKE OF 2006?
A: Let us count the ways:
(1) Light weight: Every motorcycle manufacturer gives lip service to the concept of "centralization of mass." It's the latest buzz word. But Yamaha went all-out in lowering the crankshaft, frame, subframe, radiators, engine and oil tank. Nothing feels as light as a YZ450Fnot even a 250F.
(2) Powerband: Imagine that you could take the smoothness of a KTM 450SXF, the torque of a KX450F, the quickness of an RM-Z450 and the usability of a CRF450 and combine it all into one package. The end result would be the 2006 YZ450F powerband. It's fast without being scary.
(3) Vibration free: We've never felt an engine this smooth. The counterbalancers on most engines, if they even have one, dampen out approximately 65 percent of the vibes. Yamaha is the first manufacturer to go to a 100 percent balance factor. How did they do this? The tungsten alloy balancer is heavier and smaller.
(4) Suspension: There is no doubt that Kayaba's new SSS forks are the best on the track in 06. Switching from position-sensitive damping to speed-sensitive damping has made the latest Kayabas very fluid (and still resist bottoming). The shock is a works shock: 18mm shock shaft, Kashima coated internals, 30-percent larger reservoir and titanium shock spring.
(5) Five-speed tranny: Compared to last year's four-speed tranny, the new five-speed has the same first gear ratio (1.929) and a lower second (1.533), third (1.278) and fourth gear (1.090). Fifth is, of course, taller (0.952).
Q: HOW DIFFERENT IS THE 2006 YZ450F FROM THE '05 MODEL?
A: The hubs are the same. That's all she wrote.
Q: DID YAMAHA MAKE ANY CHANGES TO THE 2006 YZ450F ENGINE?
A: How much time do you have? Rather than bore you with a bunch of specs and techno garbage, we'll only hit the highlights.
(1) All the castings are different.
(2) The cylinder sits four degrees more upright.
(3) The exhaust port shape has been enlarged at the bell mouth opening.
(4) The cylinder head and carburetor are held on with bolts instead of studs and a band.
(5) The mid-pipe is 1.5mm smaller in diameter, and the muffler has seven percent more packing.
(6) The connecting rod is stronger.
(7) The new counterbalancer rides on double ball bearings.
(8) The oil tank, which was in the frame in 2005, has been moved to the engine cases.
(9) The gearbox is now a five-speed instead of a four.
Q: IS THE 2006 YZ450F FASTER THAN THE 2005 YZ450F?
A: Yes, yes and yes. Why did we say yes three times? That's simple. The YZ450F is faster, smoother and more usable. There is no way to dance around the powerband of the YZ450F. It's a dream of a ride.
Q: DID WE HAVE TO CHANGE THE GEARING ON THE YZ450F?
A: We didn't have to, but we did. For hard-core racing we think that one more tooth on the rear sprocket is the hot setup. But, this isn't a slam dunk change. Some test riders liked the broader power delivery of the stock 49-tooth gearing over the instant response of the 50.
Q: HOW GOOD IS THE FIVE-SPEED TRANNY?
A: The MXA wrecking crew has ridden all of Yamaha's four-stroke works bikes. That means we have sampled the factory-built five-speeds, four-speeds and three-speeds. Of all the gearboxes sampled, we preferred Tim Ferry's three-speed YZ426F.
That said, we love the new five-speed. It offers a wide variety of riders the ability to have a gear for everything from trench digging to racing across the Bonneville Salt Flats.
Q: HOW GOOD ARE THE 2006 YZ450F FORKS?
A: For decades Kayaba was the big cheese of the suspension world, while Showa played second fiddle. Then, a few years ago, Showa got their act together, while Kayaba started juggling back and forth between bumper and bladder internals. It was a losing proposition. Kayaba, to their credit, came up with a quick and easy solution to their suspension woes. Starting with their AOSS (Air/Oil Separate System) in 2005, they simply cloned Showa's winning formula. For their effort, Kayaba got improved performance, even if critics called their new forks "Showabas."
For 2006, Yamaha dropped last year's Kayaba AOSS forks for the new SSS (Speed Sensitive System) forks. They are very good. We fiddled with the rebound, but stayed very close to the book settings. In our opinion, the SSS forks absorb every size bump and work with the chassis instead of against it. The damping is spot on.
Yamaha increased the spring rate from 0.46 kg/mm to 0.47. The SSS forks resist bottoming, absorb little bumps and don't get harsh over the medium-sized stuff. The average rider should start with the compression on ten out and the rebound on nine out.
Q: WHAT ABOUT THE SHOCK?
A: This is a works shockno kidding. It might as well have been stolen from Chad Reed's bike. It has three works parts that few other showroom stock shocks offer:
(1) The 2006 shock has an 18mm shock shaft. It is 2mm larger than last year's shock shaft. The larger shock shaft displaces more oil, which means that more oil is pushed through the valving sooner, which results in a more sensitive feel on small chop.
(2) All the internal parts of the YZ450F's Kayaba shock are Kashima-coated to reduce friction. In addition, the shock reservoir has been increased in volume by 30 percent to help control the heat (to compensate for the shock shaft's increased displacement).
(3) The shock spring is made from titanium, but not just any titaniumit is American Ti. The spring rate has been increased from 5.3 kg/mm to 5.5.
All of these changes produce a shock that is more responsive to low-speed oscillations and ready, willing and able to take on big hits. It is very important to run your sag at 98mm. The bike is more stable at that setting. If you want to have the rear end hang down a little lower, you can achieve that by turning the high-speed compression dial out a quarter of a turn. As for the compression and rebound, we left them alone.
Q: HOW DOES IT HANDLE?
A: The MXA wrecking crew is full of nit pickers, which is exactly what you want out of a test rider. If you are reading bike tests for glowing praise of your personal steedmove on to another mag. We expect perfection! We demand it! And we have found it in the 2006 YZ450Fwith a few minor mods.
Yamaha has leapfrogged to the top of the handling heap with their new aluminum frame. This bike is a revelation. The first words out of every MXA test rider's mouth were, "This thing is light!" Yamaha's effort to move literally every major part of the engine lower on the chassis has paid tremendous dividends in the handling department. This bike feels like a feather.
It rolls into corners with ease. The top-heavy feel of the old YZ450F is gone, replaced with the sensation of a bike that is 20 pounds lighter. So, how much lighter is the 2006 YZ450F than the 2005 model? Zilch. Zero. Nada. It weighs exactly the same230 pounds.
Thanks to the wonders of gravity, rotational moments of inertia and mass centralization, Yamaha found a way to lose weight without actually changing the number on the scale.
Q: WHAT WERE THE MINOR HANDLING MODS THAT WE MADE?
A: Every MXA test rider complained about understeer when they first threw a leg over the bike. It had a tendency to push at turn-in and a desire to be throttle steered from the center-out. Luckily, we tuned this out with three simple changes.
(1) Handlebars. The stock handlebars are too low. Switch out the stock bars for a taller bar bend (or 10mm taller bar mounts). We can't stress enough how important this change is. We spent a whole test session trying to get rid of the stink bug feel before we realized the bars were the culprit.
(2) Race sag. Set the race sag at 98mm. We know that the recent trend has been to run about 105mm of sag, but with the YZ450F's new aluminum frame, stiffer swingarm and stouter shock spring, we think 98mm is perfect.
(3) Fork height. Slide the forks up in the clamps to the first line etched in the fork tubes. By raising the forks, we steepened the head angle. The steeper head angle improved turn-in.
Q: WHAT DID WE HATE?
A: The hate list:
(1) Widgets: We are confused by the monstrous hot start trigger on the bars and the front brake hose clamp on the forks. Let's all think small.
(2) The bars: The oversized Pro Taper Contour aluminum bars are first-rate, but they are too low.
(3) Grips: You need tough hands to like the Yamaha grips.
(4) Titanium footpegs: We'd be willing to trade the titanium footpegs in for 57mm steel pegs. Until then, Lightspeed will sell you a set for $99 at (714) 990-5767.
Q: WHAT DID WE LIKE?
A: The like list:
(1) Plastic. If we were buying a 2006 YZ450F, we'd buy the 50th Anniversary yellow edition. It looks cool, but costs $200 more.
(2) Thought process: Yamaha did their homework. The rear brake caliper has the bleed screw moved so it won't hit the muffler. The on-the-fly clutch adjuster is jumbo-sized. The shock spring is titanium. The seat foam is 30 percent thicker, but the seat is 20mm lower.
(3) Oil tank: The integrated oil tank gets a major source of weight as low on the chassis as possible.
(4) Tires: For years Yamaha delivered the YZ450F with hard-pack Dunlop 739 tires. The solid performing 739 stays on the front, but the rear is replaced with a 756 that's much more multipurpose.
(5) Triple clamps: The wait is over. The handlebar mounts are adjustable.
Q: WHAT DO WE REALLY THINK?
A: This is a great bike. It is, without a doubt, the best 450cc motocross bike sold. You should buy onenow!
For more 2006 Bike Tests go to Top Ten Stories