Fake Blow Job

From Visordown:-

It appears that the bike’s electric drive motor - in addition to putting power to the wheel - spins a crankshaft that runs a four-stroke engine that sucks in air, moves pistons about, and spits said air out of an exhaust pipe. All of that replicating the sound and feel of the powerplants that have been driving motorcycles for more than a century.

Read more here if you're interested:-

Yamaha patents fake engine to give electric motorcycles a real feel | Visordown