Honda Thailand recently showcased a 400cc version of their new 471cc parallel twin engine that serves the CBR500R, CB500F and CB500X. This new engine variant is de-tuned and Honda say that they have specifically developed this engine for the Asian market.
The physical appearance of the de-tuned version is exactly like that of the 471cc engine. Only the stroke length has been reduced to 56,6mm, which has brought down the capacity to around 400cc. The bore size remains the same as in the 471cc engine, though. On thing that still remains a mystery is the power output of this de-tuned engine. We can safely surmise that this engine will produce around 40 horsepower. This engine makes perfect sense for the Asian market as the trend is not shifting from 250cc machines to slightly bigger machines with KTM, Triumph and a few other brands ready with machines in the sub-400cc segment, it would be really interesting to see how well a Honda with this new engine does in the market.
Other sources say that the 400cc parallel twin engine is specially developed for the Japanese market, and even other tell that the 400cc parallel twin will be used to power a light cruiser as a replacement for the Honda TA200 Phantom. The only facts we now know for sure are that the engine is real, and Honda has not revealed any additional information.