The new YZ450F features a much smaller muffler for 2008 but is claimed to meet AMA regulations.
went all-out on the 2006 YZ450F
so 2007 was pretty slow in terms of upgrades and 2008 isn't much different. Yamaha engineers put together a small package of changes that they hope will keep the bike atop the 450 wars like it was in MotoUSA's 2007 450 MX Shootout. That could very well be the case with the changes looking to be non-influential on the super-smooth, deceivingly fast motor our testers came to love.
The only thing that looks to change the power characteristics are reshaped intake ports and revised cam profiles to give better throttle response off the bottom - one area where we'd like to have just a tad more. The biggest change, however, or smallest as the case may be, is the new muffler. This "punched cone" unit is much shorter than the previous model - 35% by Yamaha's claims which equates to roughly six inches! It essentially looks like a chubby 2-stroke silencer. Not only is it much better looking in our opinion, but it supposedly drops over half a pound while staying within the 99 dB limit for AMA racing. Like the 2007 model, the titanium head pipe swells from 41.3mm at the exhaust port to 45mm, but this year the taper is right out of the engine rather than midway through the header.
Yami also slapped on the front brake assembly from the YZ250F which was all new last year. The smaller caliper pistons and lighter wave-style rotor shave some weight, but we didn't feel any big performance improvements. At any rate, lighter is better, so we'll see how the 450 clamps down later this year. The steering head pipe and stem are 5mm shorter as well.
The '08 YZ450F
has all of the same length and width specs for wheelbase (58.8 in), seat height (38.9 in), ground clearance (14.7 in), etc. On top of that the rear Dunlop 756 is now a 120/80-19 for a better grip on the Blue groove, if you know what I'm sayin'. The MSRP has risen an extra C-note to $7099 ($7199 White).
Both of the 4-stroke YZ models, like this 250F, will be available in white for an extra hundred bucks.
The quarter-liter YZ-F gets a boost in compression from 12.5:1 to 13.5:1. Alongside that are jetting and ignition changes, and probably a penchant for higher-octane fuel. Time will tell if the extra pressure leads to decreased longevity or hard starting to go with a likely boost in bottom to mid response. Fork internals got the annual massage and Yamaha
upped the ante for grip with a new set of Bridgestone M404 rear and M403 front to replace the Dunlop tires of old, and widened the stainless footpegs to 55mm (up from 45mm).
The 2-stroke Yamaha lineup is alive and well with some new changes for the ring-dingers. The YZ85 is a carryover model, but the YZ125 and 250 both received the YZ250F-style front brake assembly, suspension valving adjustments, lighter outer tubes on the 48mm Kayaba fork, and lighter fork protector, front axle and wheel collar. The axle and wheel collar are shared revisions with the 4-strokes. Exclusive changes are limited with the one-two-five getting a new reed-valve spacer. None of the two strokes are available in white, and each has received the $100 boost in cost.
All of the motocrossers and off-road bikes get matte black finish on the clutch and ignition covers for some extra style points.
WR450F - WR250F
Not only have the MX machines gotten a re-working, but the off-roaders are upgraded for 2008 as well. Last year was the first time that the WR450F and WR250F were constructed around an aluminum chassis. With such a big emphasis on those bikes in 2007, they only got a sprinkling of upgrades for '08. The 250F gets a re-shaped brake pedal, new breather and fuel hoses and an additional 2Ah of battery power (6Ah vs. 4Ah). The 450 also has the new hose arrangement and the backlash between the clutch primary gears and balancer gears is said to be reduced for less engine noise - something we noticed a lot of with the extra-quite muffler installed last year. MSRP figures remain the same ($7199 - 450F, $6399 - 250F).
has taken on the 110 market by boosting its TT-R90 displacement and dropping the smaller machine from the lineup. We'll have to see if GYTR comes up with a bunch of grown-up bolt-ons like it did for the TT-R50E.
The Blue play bikes are mostly carryover models including the TR-R230, TT-R50 and PW50, but the TT-R125L is an exception. The L, LE and E models all get a thinner, flatter seat with firmer foam and YZ-inspired plastic to give the bike a racier feel and look, and the 31mm fork gets all new internals. The big news this year is the addition of a completely new model - the TT-R110E. After the positive response to the electric-start TT-R50 as an alternative to the Honda CRF50, it was a no-brainer for Yamaha to go after Kawasaki's virtual lock on the larger-displacement mini market and the KLX110.
The new bike, which replaces the TT-R90, has an air-cooled, SOHC powerplant with a 110cc displacement. A 9.3:1 compression ratio requires a key to get lit, but the rest is easy with the magic button to help junior get on his way without a single kick. An automatic cam chain tensioner and tool-free air filter access offer ease of maintenance and a USFS-approved spark arrestor lets kids explore the wide world of motorcycling through all four clutchless gears.
The front and rear brakes are 95mm and 110mm drums, respectively and attached to a 14/12-inch tire combo. A 31mm fork offers 4.5 inches of travel while the shock puts up with 4.3. The aftermarket companies can get crackin' on hop-up goodies for the new motor, but if you plan on making this your base for some ultra-mini project it'll cost you $1849 and you'll have to wait until September to get started, the same goes for the 230. If waiting that long is simply out of the question, you can pick up a new TT-R50 or 125 as early as August.
Let us know what you think about the 2008 Yamahas in the MotoUSA Forum