“This engine is excellent, it pulls superbly, already at low and mid revs” says test rider Jeffry de Vries. “The throttle response is so immediate and direct, and you feel you have a lot of power, always. It’s a treat to ride it. There are some characteristic vibrations and they are nice too. Instead of being annoying, they give a certain character to the bike. It’s a new experience.”
In fact, this modern and fuel-efficient engine incorporates the latest racing technologies. They combine power and precision with light weight.
Its DOHC engine design features downdraft intakes, forged pistons, plated cylinders and fracture-split connecting rods.
“We were able to make this engine 10 kilo’s lighter than the 4-cylinder FZ-8 engine” states Project Leader Akira Kimori.
The cylinders are offset by 5mm from the centre of the crankshaft to reduce friction losses: a recent Yamaha technology already applied in the YZ450F motocrosser.
By offsetting the cylinders, the conrod position is more straight under the piston at the moment of greatest combustion force and the piston is not pushed into the cylinder wall so strongly. This also improves fuel efficiency.
The fuel injection uses 12-hole injectors that are attached directly to the cylinder head for precise and efficient injection directly at the valve skirt. At the same time, this position enables a shortening of the throttle body, for better performance in the high rpm range.
Yamaha’s fly-by-wire throttle (YCC-T) ensures an exciting and direct throttle response which can be adjusted by the D-mode system in three different settings.
Even the water cooling route is kind of unique: our engineers developed a layout with short hoses and a thermostat located before the water pump, resulting in light weight and quicker warm-up (which even helps for fuel efficiency and emissions too).
Also remarkable on this engine are the intake funnels that contribute to the excellent intake sound. They have been designed with uneven lengths. The first cylinder funnel is 102.8 mm, the second 82.8 mm and the third is 122.8 mm so that the power and torque curves produced by each intake, complement one another positively. This results in excellent torque characteristics in the middle rpm range and up. And it also helps to give a pleasing, fine-tuned intake sound.
Inside an engine there are two main forces creating the final pulling force at the drive axle.
The first one is the combustion torque: created by the explosion in the cylinder.
The second force is the inertial torque: created by the rotating mass of the crank and the mass of the pistons moving up and down.
Especially the inertia created by the pistons that have to stop and reverse their motion at the top dead center and top bottom center of the piston stroke, interfere strongly with the combustion torque (as you can see in the graph).
In a normal in-line 4-cylinder engine, two pistons always rise and fall at the same time, and the four pistons are all at the same time in a dead point (two in top dead center and two in bottom dead center), which creates high forces that work against the combustion torque.
Yamaha already developed the famous 4-cylinder ‘crossplane engine’, in the M1 race bike and the R1 supersports, to harmonize the interference of combustion and inertia torque. We call it “clean torque”.
In the 3-cylinder engine, there is a similar clean torque effect. The pistons rise and fall 120 degrees apart so they are never in a dead point at the same time and the inertial torque is much less and also less interfering than with a normal in-line 4-cylinder. So both the crossplane P4 and the P3 engine have the clean torque delivery which is in line with Yamaha’s philosophy to create a unique interaction between rider and machine.
The result is that the rider can feel a more direct connection to the combustion torque. In short, better control of engine power, resulting directly in more excitement!
“We did not want to make just another allround midclass bike” says Oliver Grill of Product Planning. “The MT-09 should be a high capability bike, built for serious riding performance.”
The chassis components on the bike are a clear example of that thinking.