As Honda continues to dribble out all the details on the VFR1200, more information about the V4 motor is starting to surface, and it is shaping up to be one of the most technologically advanced power plants in the motorcycle world.
You’ve probably already read about how the VFR1200 will incorporate a dual-clutch gearbox, and now Honda has released more information on the V4 configuration itself, which will include space/weight-saving design elements, cylinder deactivation, and a unique firing order. Video, patent diagrams, and more after the jump.
The motor will have unequally spaced front and rear-cylinders, with the front cylinders set wider apart than the two rear cylinders. Standing at 28º a part from each other, the nearly vertical banks on the V4 reduce vibrations from the “V” configuration, making for a smoother motorcycling experience.
Honda has also abandoned conventual widsom when it comes to piston-firing orders. Instead of alternating piston pulses between the front and rear banks (pistons 1 & 3 up front, 2 & 4 in back), Honda is firing the banks one after another, (pistons 1 & 4 up front, 2 & 3 in back). Note, this is not a big-bang firing order, but it does allow Honda to create a compact motor that still has the characteristics of a V4.
Other innovations include a single camshaft or “unicam” (a la Honda CRF), which reduces the weight created from a double camshaft design (DOHC). Also, the V4 has no balancer, and a phase-pin crankshaft, making the motor weight reductions that much more drastic (balancers are typically found on every motor design, except boxer motors).
Helping riders save money at the gas pump will be Honda’s cylinder management system, which increases the number of cylinders used as the throttle is opened wider in relation to engine speed. To make this happen, the rear-cylinders will operate at all throttle points, and the front two cylinders will be engaged as required. Since the rear bank will be operating continuously, Honda has cleverly cut a gap between the front two cylinders to air could pass to rear bank while at speed. Check the chart below to see where those cylinders will be activated.