2003 Yamahayz450f
2003 YAMAHAYZ450F
CW RIDING IMPRESSION
Survey says...
JIMMY LEWIS
C'MON, DID YAMAHA REALLY NEED market research, focus groups and owner surveys to find out what changes the new YZ450F needed? After all the charts and graphs were trotted out, was it really a surprise that riders were satisfied with the current 426’s power, suspension, handling and durability; they just wanted less weight and easier starting? Straight from The Book ofDuh. Geez, try reading the magazine once in a while, Yama-guys, it’s right here on the pages.
However the answers were arrived at, Yamaha knew it could not afford to stand still. Little number by Honda, the CRF450R, saw to that. Our pick for 2002 MXer of the Year, Honda’s Thumper had set the bar pretty high.
The WB Ranch in central Texas, home of the fabulous Lake Whitney motocross track, was the location for a couple days of wringing out the new YZ-F. This manicured, park-like facility has some deep loam and hardpacked sections, with rolling turns and fun jumps. Overall, a great place to put some serious laps on the new bike.
Over the last 18 months, every nut, bolt, tube and casting was scrutinized by Yamaha engineers and test riders. There are more than 185 outright changes to the new 450. And, of course, displacement had to increase-who wants a puny 426 anymore?
Efforts were made to reduce reciprocating mass. Half the bike’s weight loss, nearly 6 pounds, was scrubbed off the motor and related components. Yamaha now has sufficient experience with four-stroke MX motors to be aware of what parts were overbuilt. So now we have a lighter crankshaft and flywheel. There were simple moves like integrating the coil into the sparkplug capcurrent streetbike technology-and reducing overall oil capacity. Transmission is now just a four-speed, as testing showed fifth was rarely used on even the fastest MX circuits. And thanks to bigger gears, tranny durability should be even better. Though the motor is now a tad longer front-to-back, it appears to have been shrinkwrapped, just like the YZ250F’s.
More weight-savings: All of the plastic got a bit thinner; brass or steel parts in the suspension are now aluminum; titanium replaces steel in the muffler; some of the aluminum case guard is now plastic. For all intents and purposes, this is about as light as a big production four-stroke can get and retain an acceptable level of durability. Lucky for Yamaha, the F weighs-in a pound lighter than the Honda 450, or so the claimed dry weight of 232.5 pounds would indicate.
But so much for the scales, what about the ride? Well, from the first kick, it’s clear this ain’t your old 426. A cam-mounted automatic decompression device means that the Yamaha line now-^/maZZy-has a kick-n-go Thumper. Throttle response is as crisp and lively as we’ve come to expect from the YZ-F, but is something that can easily get lost in just boosting piston stroke, which is the way Yamaha got its extra 23cc. First gear is a bit taller than before, but there’s also more power right off idle, so the cog change goes all but unnoticed. In fact, power output is fatter everywhere, especially on the bottom. The feel is a bit crisper and smoother than the CR450, as though the Yam has a lighter flywheel than the Honda. There are no dips in the YZ’s power ’til it signs off via a rev-limiter at 11,200 rpm. This seamless power spread complements the new transmission well-secondgear starts are easy, and you ride most of the track in third, with second for tighter turns. Compared to the 426, the 450 lugs down with much more authority and really pulls out of turns, while still retaining the ability to scream its brains out. It may rev ever so slightly slower than the 426, but learn to trust the torque at lower rpm, lay off the shift lever and watch your lap times improve.
With the motor so good, we’re also happy to report that the chassis is just that much better. The previous heavy feel through the bars is gone and now the bike has a genuine flickability, a trait the 426 was lacking, either in the air or dropping into turns. Losing weight helped here, as did keeping the aggressive-yet-rideable engine character. But credit also the flatter seat and smaller gas tank, now down to 1.8 gallons, which makes it even easier to move forward on the motorcycle. Instead of the F pushing into turns, now it just flows, and you don’t have to fight to make line changes. The front tire feels better planted now. Not cemented, though. The biggest issue we had with the new bike was getting the front end to stick in highspeed sweepers. Blame the extra power, ’cause the front gets real light real fast.
We ended up running a bit less than the recommended 102mm of shock sag in favor of 96mm, and also had luck sliding the fork tubes up in the triple-clamps about 3mm. Turning everywhere got even better with these tweaks as the bike now had a little more weight on the front tire in fast sweepers. Other than that, we never touched the suspension clickers. Past Yamahas have been typically stiff in the beginning of their travel, becoming plush through the rest of the stroke.
The stiff beginning was a way of making the midstroke less harsh-the mid-stroke was needed to slow the suspension from bottoming too hard on big hits. This year, the bike is definitely more compliant in its initial stroke and there isn’t any indication of mid-stroke harshness, though the bike will bottom on the really sharp bumps or miscalculated jump landings.
Component-wise, don’t sweat it, they’re as solid as we’ve come to expect from the YZ line. New lightweight brakes are as strong and controllable as ever, especially the front, which needs to be this good on a faster bike. The fit of things is nice and tight, and even though the plastic is thinner, it seemed to hold up as well as the old stuff, never mind those white marks after a few falls. The thinly padded seat had a few people concerned. Hey, this isn’t a trailbike; you aren’t supposed to be sitting down much during motocross! Fuel range? We got 45 minutes on a slippery, hard-packed track and had a small amount of gas left.
So, let us bottom-line it for you. After two long days in (okay, over) the saddle, we’re able to confinii that Yamaha has hit or exceeded every one of its targets for the YZ450. No, we did not have a CRF450 on hand to answer The Big Question. Watch this space in coming months. But we do know this: Fact #1 ) The Yamahas are going to sell fast at a list price of $6299, and they’re in dealers right now. Fact #2) No matter what, you won’t go wrong with the YZ450F.
