Well, its not as easy to find in google as you'd probably want. Here's an excerpt from the press release in late 2015...but, being a press release it is very light on technical details and more into hype...FWIW
New CVT set-up in conjunction with revised clutch linings for more dynamic clutch engagement and a more spontaneous set-off response.
• New suspension and damping set-up for an ideal compromise between
sport and comfort.
• In addition to ABS, now also ASC as standard for maximum safety when
accelerating.
• Completely new, dynamic design for the C 650 Sport.
• Detailed stylistic fine-tuning for the C 650 GT.
• New silencer for a fuller sound and more dynamic appearance.
• New instrument dial design.
• New handlebar trim elements with chrome applications.
• New, higher-quality surfaces (graining effects).
• Automatic daytime riding light.
• Revised kinematics of the centre stand for easier use.
• New rider assistance system Side View Assist (SVA) for the C 650 GT.
• New paint finishes for the C 650 Sport: Valencia Orange metallic matt,
Lightwhite non-metallic and Blackstorm metallic.
• New paint finishes for the C 650 GT: Blackstorm metallic, Frozen
Bronze metallic and Lightwhite non-metallic.
2. Vehicle technology and design.
Powerful 2-cylinder in-line engine with new set-up, optimised CVT and new exhaust system.
In the new C 650 Sport and the new C 650 GT, the 2-cylinder in-line engine with a capacity of 647 cc once again ensures dynamic propulsion. The rated output in both models is 44 kW (60 hp) at 7 500 rpm. The maximum torque of 63 Nm is available at 6 000 rpm. The maximum engine speed is 8 500 rpm. Both models are also available in an output variant with 35 kW (48 hp) at 7 000 rpm and 54 Nm at 4 250 rpm.
In order to achieve a low mounting position and therefore a low centre of gravity, the engine has a cylinder bank that is tilted forward by 70 degrees. The characteristic sound and low level of vibration are due to the 90-degree crankpin offset, 270-degree ignition spacing and two counterbalance shafts powered by spur gears.
The sophisticated cooling concept to BMW Motorrad standards ensures optimum thermal balance in the 2-cylinder in-line engine. Here, coolant flows transversely through the cylinder head, entering at the front of the cylinder head on the hot exhaust side. The intensive cooling effect rapidly dissipates the heat precisely at the point of maximum thermal stress, thereby ensuring excellent temperature compensation. The aluminium radiator with plastic water containers and integrated thermostat has the same high-performance radiator network as is used in BMW motorcycles. Due to its high degree of efficiency and excellent air intake and through-flow, a relatively small surface is sufficient for operationally reliable heat dissipation in all conditions.
Carburation of the 4-valve engine with two overhead camshafts is taken care of by an electronic fuel injection system. Meanwhile oil is supplied by a dry sump system with a dual oil pump, and an efficient cooling concept ensures optimum thermal balance in the 2-cylinder engine. Engine mapping was redefined for use in the new C 650 Sport and the new C 650 GT with a view to satisfying the requirements of the EU4 pollutant class.
Power transmission is by means of a directly integrated CVT
(Continuously Variable Transmission) which underwent extensive adaptations for use in the new C 650 Sport and the new C 650 GT. As a result, a new CVT set-up in conjunction with an optimised clutch provides a more spontaneous set-off response at traffic lights, for example.
Softer springs and optimised clutch linings are used in the centrifugal clutch.
In addition to increased roller weights, the transmission ratio spread of the CVT has been increased from 2.42 to 2.95. The long CVT ratio is now 0.82 instead of 1.00. The gear reduction ratio between the CVT output shaft and driven shaft has been shortened from 2.72 to 3.28.
In addition to a more spontaneous set-off response, this also makes for an increased top speed (180 rather than 175 km/h).
The new exhaust system is made of stainless steel as before, but does not have a front silencer in the new C 650 Sport or the new C 650 GT. Fitted only with a rear silencer, it now offers a particularly full and sonorous sound.