The funny thing is all the changes from last year are comfort-oriented: slightly softer damping and spring rates and a better seat. They all work as advertised, but it's the overall moto orientation that hurts the Yamie in a test such as this. Stiffer sidewalls on the tires and an aggressive ergonomics package work wonders for the quad on the track but cause it to wear down a rider on a rough off-road course. Even the usually YFZ-mounted pros had some colorful descriptions for the Yamaha after their hour-long stints, none of which we can print here.
What's changed from last year: Revisions for '05 include front suspension tweaks (a new front spring rate and damping help reduce rider fatigue through increased low-speed bump absorption) and Yamaha's addressing its stiff seat (the seat now has softer, more-durable foam and a nonslip cover). The '05 YFZ also received forged-aluminum shift and brake pedals.
+Best MX platform
+Super-strong engine
-Flat-prone tires
-Hand-numbing thumb throttle
=Great MX quad
Yamaha YFZ450
Retail price: $6899; Special Edition, $7099
EngineType: Single-cylinder, four-stroke, five-valve DOHC
Displacement: 439cc
Cooling: Liquid-cooled with fan assist
Carburetion: Keihin FCR 39mm
Lubrication: Dry sump
Starting: Electric
Drivetrain
Drive system: Chain, 2x4
Transmission: 5-speed manual
Suspension (Type/Travel)
Front: Dual A-arms, independent/9.1 in.
Rear: Swingarm/10.1 in.
Tires
Front: 21x7-10; rear: 20x10-9
Brakes
Front: Dual hydraulic discs; rear: hydraulic disc
Dimensions
Wheelbase: 50.4 in.
Claimed dry weight: 350 lb
Ground clearance: 4.4 in.
Length/width/height: 72.4/46.1/42.9 in.
Seat height: 31.5 in.
Fuel capacity: 2.6 gal.
Electrical
Taillight: Yes
Headlight: Dual 30-watt high/low beam
Instrumentation: NA
Colors: Team Yamaha blue/white, white/red; Special Edition yellow/black
What Broke: As with most of the machines, the Yamaha suffered from repeated flats, but the wheels held up pretty well. The rear plastic skid plate and rear brake disc also were fairly hammered early on in the event. In fact, the rear brake disc had to be pounded into a somewhat flat shape on at least two occasions, just so it wouldn't keep the rear wheels from turning.
#3 Suzuki QuadSport Z400
Many riders felt the Z had one of the best-handling chassis of the group and extremely user-friendly ergonomics. It simply lacked the grunt in the engine department to compete against the other machines in this shootout. But when you factor in its price in comparison with the others (especially after taking into account all the updates it received this year), that may be enough for most casual trail riders to boost it to the top of their list.
It also had the most serious problems in our test (maybe it was the racers trying to keep up with the faster test mules). About halfway through the event, the rear shock gave out, mostly blowing through its stroke. Still, it was more comfortable to ride than the YFZ; you simply had to go slower (try telling that to some of these guys). It was actually a good thing we called the test when we did, as we had just run out of round wheels for the Z, and the tires looked like pincushions with all the plugs in them.
What's changed from last year: The Z received a new aluminum front bumper and rear grab bar; a larger (37mm Mikuni) carb with a throttle position sensor linked to the ignition system; redesigned cam profiles for increased power output; an additional clutch drive plate (from eight to nine); a new aluminum gear shift pedal for weight reduction; a magnesium clutch cover, valve cover and ignition cover; and new reservoir-type front shocks.