BMW has revealed details of its new ‘Big Boxer’ engine that will power a range of cruiser and touring models, putting it in direct competition with established segment players like Harley-Davidson and Indian Motorcycle.
It lives up to its name with a capacity of 1,802cc, making it the largest twin-cylinder boxer engine ever to feature in a series production motorcycle.
The Big Boxer is an air- and oil-cooled unit, with large ribbed cylinder heads, featuring an aluminium housing and weighing in at 110.8kg.
The engine will have a power output of 91hp at 4,750rpm, and a more impressive torque output of 158Nm at 3,000rpm. Ensuring a wide spread of power, BMW claims that more than 150Nm will be available from 2,000rpm and up to 4,000rpm.
It has a 107.1mm bore and 100mm stroke, will idle at 950rpm and redline at 5,750rpm. The fitment of a large flywheel and all that pulling power should make for a relatively smooth operation on the move.
When the Big Boxer is installed into its first production model, it will use a single-disc dry clutch set-up for the transmission.
To reduce the risk of rear-wheel stamping through quicker downshifts, it will use what BMW describes as a ‘self-reinforcing anti-hopping clutch’ to keep everything under control.
The six-speed constant mesh transmission is designed as a four-shaft unit with helical gear pairs. A shaft drive system will continue to be used, and there will also be the option of having a reverse gear — likely to be used on larger touring models — that is selected manually and driven by an intermediate gear and electric motor.
Expect to see the first production model with the engine debut early in 2020.