Engine excellence
To support the great looks and high performance chassis, Yamaha used the same engine that has become a hit in the YZF-R125. The single cylinder four-stroke engine uses the latest technology and complies with future emission regulations.
It is a newly developed, ultra modern engine: liquid cooled, with 4-valve cylinder head, fuel injection and catalyser it is set up for low emissions and low fuel consumption.
The EU 125cc licence sets a power limit at 15 HP. “We tried to make the ultimate within this regulation” confirms Toshiharu Shigeta – who created this engine for the YZF-R125. The result is a lively ‘regulation conforming’ engine with a good character and torque, well ahead of its 4-stroke competitors!
Yamaha’s engineers took the well-suited R125 gearbox and altered the final gear ratios to suit the different speeds and requirements of both the WR125X and WR125R. The power feeling can be felt easily and positively which was a major requirement switching from a two-stroke engine to a four-stroke engine.
The induction and exhaust were both altered from the R125 components to make the engine performance more suitable for off-road and supermoto riding.