The Bullet Classic 500 UCE is technologically more advanced compared to other Royal Enfield motorcycles.  This unit construction engine features a fuel injection system which has been throwing up the occasional problem due to not have an O2 sensor.  To overcome the problem Royal Enfield is re-mapping the fuel injection system but still does not plan to incorporate the O2 sensor.  It was this problem that started a rumour that Royal Enfield will go for a carburetted engine, which has since been denied.