2012 Yamaha YZ250F
The 2012 Yamaha YZ250F has the most reliable engine in the 250 class and in the right hands it has the capacity to be among the fastest bikes on the National/Supercross circuit. In 2012 Yamaha continues with the Keihin FCR carburetor, producing a broader powerband and more horsepower than a EFI 250—especially when joined to a series of intelligent upgrades.
For the new year, the YZ250F Yamaha receives a 2mm large carb bore from 37mm to 39mm, for a more top-end power—especially from 8000 rpm to 12,000 rpm. Yamaha reduced the reciprocating mass of the piston and the balance of the crankshaft, reducing vibrations at the bars, pegs, and saddle. There is also a new air filter cage that flows more air to go along with the revised engine mapping and a muffler with an 8mm smaller core diameter. The piston is 8.7% lighter than it was last year. Plus, there are new piston rings with reduced friction and a lighter piston pin and circlips. The crankshaft balance and counter-balancer have been revised for a smoother performance. Additionally, the connecting rod and big-end bearing get a new heat-treating process for more strength and improved durability... MORE