Is Royal Enfield developing a single-cylinder 400cc engine?

A report on Autocar Professional quotes that Royal Enfield is working on a 400cc engine, which will be based on it's existing 346cc single-cylinder engine doing duty on the Classic & Bullet 350. This will be more of an enhancement to the current 346cc engine, rather than an all new 400cc engine.

The most powerful engine from the RE stable is plonked in the Continental GT, which is a 535cc block producing 29 BHP; while the 350cc & the 500cc engines produce 20 BHP & 27 BHP respectively. The under-development 400cc engine is expected to be in a state of tune to generate power output which can fill the gap between the 20 - 27 BHP range.

Royal Enfield currently sells the Continental GT, Thunderbird, Classic & Bullet range of motorcycles. It will be interesting to see which of these motorcycles get the new engine block first.