The new 4-cylinder engine, with its 16 radial valves, retains only the values of bore and stroke with its predecessor: 76x55 mm. But, it takes advantage of all the experience developed in prior racing activities together the most advanced technology in order to maintain its status as the point of reference for the supersport class. It represents an evolution of the previous engine, but the advancements are so profound that it is considered a completely new engine. The profound development that it was subject to ensures exceptional performance as well as a perfect marriage of throttle control and rear wheel traction.
The crankshaft has been redesigned and the inertia has been increased by 50% compared to the previous engine. Also, the connecting rods have been completely redesigned. They are now lighter, and at the same time, stronger than the previous connecting rods.
The intake tracts have been shortened substantially to obtain the best cylinder filling efficiency and the maximum performance at all rpms. To "fill in" the torque curve and to improve the fuel supply the new 49 mm Mikuni throttle bodies have been employed in conjunction with the TSS variable intake system.
For the first time on a mass produced motorcycle, MV has integrated the new Marelli 7BM ECU to perfectly control all of the electronic systems of the F4. This new ECU controls the 8 fuel injectors in the engine management system, the variable length intake tracts as well as the exhaust control valve, the gear selection switch and the new MK II Traction Control algorithms along with the double EFI Sport and Rain maps.
The intake system has been updated by new springs and lighter intake valves. The 30 mm intake valves are made of titanium where as the steel exhaust valves have a diameter of 25 mm.
The crankcase has been redesigned and optimized and is now 600 gr (1.32 lbs) lighter compared to the previous one. The gear box is completely new and it incorporates the gear switch sensor that allows the engine control unit to adopt different EFI maps depending on the gear used.
A high performance engine like the 4-cylinder MV engine needs to be cooled and lubricated to perfection. For this reason the oil circuit has been completely re-engineered. The oil pump is now more compact and more efficient, the water/oil exchanger leaves space for a new radiator which keeps under control the temperature of the lubricant, consequently reducing the working temperature of the engine to ensure the maximum performance and reliability. The new oil pan, which is now deeper to ensure an optimal feeding to the oil pump even in the most extreme braking conditions, hosts a new ecological removable filter that can be replaced without removing any other components improving the mechanical accessibility for normal maintenance.
The water cooling circuit has been completely revised as well and the water pump has been lightened by 60 gr (2.12 oz). But, thanks to the optimized profile of the rotor, the pump has a higher flow capacity which has been increased by 65% at low and medium speed. The cooling circuit is characterized by a single flow radiator with a very high thermal efficiency equipped with 2 cooling fans and with a overflow tank.
Every single component of the engine has been analyzed, re-engineered and lightened. The new Mitsubishi generator, with rare earth magnets is oil cooled and is coupled to the with an elastomer torsional joint. The weight saving which this component contributes is: 1.600 gr (3.5 lbs).
Thanks to the relocation of elements such as the expansion tank and voltage regulator precious space for the airbox was cleared. The volume of the airbox was increased which offers the advantage of increased engine breathing and more power. The already excellent performance of the 4-cylinder MV has been improved again from this new engine which supplies the maximum power of 137 Kw (186,3 hp) at 12900 rpm.
The characteristics which have made the 4-cylinder MV over the years a point of reference in the field remain untouched. The 4 radial valves for each cylinder contribute to the optimal structure of the combustion chamber. The gear box is extractable as is the case in the most valuable racing motorcycles. The new mechanical slipper clutch ensures an optimal control of the engine brake when downshifting.
THE EXHAUST SYSTEM
The characteristic "organ pipe" exhaust system has always been a distinctive element of the F4 and it will be such also in the new version, which however optimizes the concept utilizing one scheme 4-in-1 tuned with the racing characteristics of the new engine. The 4 "outlets" under the tail section have been redesigned and are removable offering the possibility of being personalised with MV aftermarket accessories. In order to increase the efficiency of the catalyst, it has been placed closer to the combustion chamber, remarkably shortening the time required for "light off" reducing the exhaust emissions. A new electronic valve in the exhaust system optimizes the performance and contributes to the reduction of exhaust noise while at the same time maintaining the unmistakable sound of the 4-cylinder MV.