LOS ANGELES, August, 1998 -- This has been a good year for the boys in blue: Jeremy McGrath, aboard a Yamaha YZ250, won seven 250cc Supercross events en route to yet another Supercross title while Doug Henry, on a four-stroke YZ400F, is the current points leader in the AMA 250cc Motocross Nationals. Not content

The YZ400, 250, 125 and the WR400 all receive the redesigned swingarm.

to rest on these laurels, Yamaha plans to make their 1999 off-road motorcycles even lighter, stronger, and more powerful while keeping prices at 1998 levels.

YZ400F

When it comes to competition-quality four-stroke production dirt bikes, the YZ400F has no peer. No other four-stroke can compete at the track with production 250cc two-strokes. Generally, four-strokes faired poorly on the tracks in part because of weight and frame design. To help make it competitive, Yamaha designed the YZ400F with brakes, suspension, frame geometry and ergonomics similar to the competition two-strokes currently in Yamaha's line-up -- the YZ250 and YZ125.

For 1999, Yamaha's engineers have made the YZ400F even lighter. A redesigned swingarm is lighter and, according to Yamaha, stronger and more durable. Excel rims now grace both the front and rear tires. A stronger, lighter hub offers less unsprung weight on the track. The YZ400F will be available in Yamaha's Blue/White racing colors and will arrive in dealerships by September. Manufacturer's suggested retail price is $5,799 USD.

YZ250

The YZ250's engine has been reconfigured for more low-end power

For 1999, the YZ250 has been completely redesigned from the ground up with significant changes to the engine, hubs, rims, tires and suspension. To produce a longer-stroke layout and more-accessible power, the engine has been reconfigured from a more "square" bore & stroke of 68 x 68.8mm to "undersquare" dimensions of 66.4 x 72mm. The cylinder head outer diameter has been reduced from 121mm to 111mm and combustion chamber capacity is also down from 22.9cc to 22cc. A newly designed 66.4mm diameter piston features a smaller connection rod and a smaller crank pin for a quick snap at all engine speeds.

The redesigned swingarm is stronger and lighter. Excel rims grace both the front and rear, and Yamaha has added a light-weight hub and lighter aluminum spoke nipples. To improve shifting, the "3 bar" shifting mechanism found on the YZ400F has been incorporated onto the YZ250

to improve shifting when slamming down the gears after a long straight or when short shifting the bike out of a turn.

Other changes include a repositioned clutch cable that inserts directly into the transmission for reduced operation load, a new footrest and smaller footrest bracket, a newly shaped exhaust pipe and a resin silencer cap to help prevent mud clogging after spills. The YZ250 will be available in racing blue/white and will list for $5,599 USD.

YZ125

Changes for 1999 include improvements to the cylinder, carburetor, suspension, and wheels. Yamaha claims the motor will be much more potent in 1999. Exhaust port height and width have been increased, while the scavenging port has also been reshaped and enlarged to provide for increased mid and top-end power. A new exhaust pipe,

thinner walls and taper specifications have been changed to meet the engine's increased output. The governor assembly has been modified for increased reliability during valve activation. An increased ramp coupled with a ball enlargement of 2.8mm allows the motor to snap at precisely the correct time in the rev range. For improved power feel at low- and mid-speed the overall carburetor size had been reduced. Also, racers will be able to change jets within the carb without having to remove the tank. Simply loosen the bolts and turn the carb sideways.

Like the YZ400 and 250, the YZ125 also will boast a redesigned swingarm, Excel rims, a new rear sprocket and rear hubs. The YZ125 will be available in racing blue/white and will list at $4,799 USD.

Other bikes

The XT350, 225 and the TW200.

The WR400F, Yamaha's popular enduro version of the YZ400F remains largely unchanged for 1999. Improvements include a redesigned swingarm, a lighter rear hub and Excel rims. The WR4000F will be offered in blue/white and will list at $5,899. Expect it in dealerships by November. The biggest news for Yamaha's venerable line of dual-purpose motorcycles, the XT350, the XT225 and the TW200, is that 1999 prices remain the same as last year.