Yep, that's an aluminum frame! The 2005 YZ line is here, and bringing big changes to the two-stroke world. Considering that Yamaha fired the first shot in the four-stroke revolution, you might think they'd be the first to toss out the premix. Quite the contrary, Yamaha has no intentions of slowing down their two-stroke development.
The YZ250 and YZ125 are debuting Yamaha's long-anticipated aluminum frame, along with sporting radical changes to the motors and suspension. The '05 line has the lightest and most powerful MX bikes from Yamaha to date. The YZ125 claims a weight of 196 lbs (using the AMA method), and the YZ250 weighs in at 217 lbs.
Yamaha's 2005 two-strokes...
Yamaha's 2005 two-strokes are sporting new aluminum frames.
The thumpers also recieved their share of refinements, focused on improving power in the low to mid range. The changes in the YZ-F/WR machines should result in a more comfortable ride with a smoother power delivery.
Changes made to all the YZs include Renthal bars, an all new front fork system, improved plastics to prevent "bruising" and a lighter, stronger swingarm. For details on all the changes to the 2005 line of Yamahas, pick up an August issue of Dirt Rider Magazine.
 Hollows in the frame improve...  Hollows in the frame improve handling while the aluminum shaves off 4.5 lbs! |  All the '05 YZs come stock...  All the '05 YZs come stock with Renthal bars. |  The new, lighter swingarm...  The new, lighter swingarm shaves off another 1.1 lbs. |
2005 Yamaha YZ450F
| MSRP | $6,399 |
| Engine Type | 449cc liquid-cooled, 5-valve, DOHC 4-stroke with titanium valves |
| Bore x Stroke | 95mm x 63.4mm |
| Front Brake | 250mm Rotating Disc |
| Rear Brake | 245mm Disc |
| Wheelbase | 58.5 inches |
| Dry Weight | 220 pounds |
Click to visit Dirt Rider's first test of the 2005 Yamaha YZ450F.
| 2005 Yamaha YZ250 |
| MSRP | $6,099 |
| Engine Type | 249cc liquid-cooled, reed valve-inducted 2-stroke |
| Bore x Stroke | 66.4mm x 72mm |
| Front Brake | 250mm Rotating Disc |
| Rear Brake | 245mm Disc |
| Wheelbase | 58.3 inches |
| Dry Weight | 211 pounds |
Click here to visit Dirt Rider's first test of the 2005 Yamaha YZ 250
| 2005 Yamaha YZ250F |
| MSRP | $5,699 |
| Engine Type | 249cc liquid-cooled, 5-valve, DOHC 4-stroke w/ titanium valves |
| Bore x Stroke | 77mm x 53.6mm |
| Front Brake | 250mm Rotating Disc |
| Rear Brake | 245mm Disc |
| Wheelbase | 58.0 inches |
| Dry Weight | 206 pounds |
| 2005 Yamaha YZ125 |
| MSRP | $5,299 |
| Engine Type | 124cc liquid-cooled, reed valve-inducted 2-stroke |
| Bore x Stroke | 54mm x 54.5mm |
| Front Brake | 250mm Rotating Disc |
| Rear Brake | 245mm Disc |
| Wheelbase | 56.6 inches |
| Dry Weight | 189 pounds |
Click to see Dirt Rider's first test of the 2005 Yamaha YZ125.