Royal Enfield is all set to launch a new range of bikes with updated BS6-emission norms compliant engines. Many test mules with the new engine have been spied across the country.The Royal Enfield Thunderbird and Classic series of motorcycles will get updated single-cylinder 350 cc engines featuring many changes to make the old thumpers BS6-emission-compliant models. In addition, the Classic and Thunderbird motorcycles will also get design changes and a double-cradle chassis. There are rumours that Royal Enfield may do away with the 500 cc line-up, pushing buyers instead to the 650 cc twins.So what are the change that can be spotted from the spy shots?Royal Enfield Electric Bike Could Be Launched Soon & Here’s WhyThe big change is to the engines of the motorcycles. The 350 cc range will now feature fuel-injection to update it to BS6-emission norms. The engine will no longer have a kick starter and will only have an integrated starter motor. The crankcase on the left side of the motorcycle appears to have been lifted from the 650 cc twins. It’s likely that the Thunderbird and Classic will continue with 5-speed transmissions, unlike the 650 which is a 6-speed.The transmission layout has also changed. The chain drive moves to the left side of the motorcycle, while the disc brake assembly with ABS is on the right side. The front brake disc has shifted sides - from the left to the right side of the wheel.Spy Photos Suggest New Royal Enfield Classic Coming SoonThere are significant changes to the instrument cluster as visible on the Thunderbird spy shots. The twin-pod cluster will have an analog speedometer with a digital screen within that would show other information like fuel levels, gear indicator, etc. The tachometer, although missing in these spy shots will likely remain an analog unit.The Classic 350 is also likely to get the analog speedometer with the central digital screen, but may not get a tachometer, keeping in tune with the current retro design. Other changes include a rework to the chassis, different swingarm and placement of the tail-lamp and number plate.The new motorcycles are likely to be launched by March 2020 ahead of the BS6 deadline of 1 April 2020. They will compete with the Benelli Imperiale 400 and Jawa bikes among others. Currently, the Royal Enfield Classic is the best-seller in the segment.Benelli Imperiale 400 Launched To Rival Royal Enfield Classic 350 We'll get through this! Meanwhile, here's all you need to know about the Coronavirus outbreak to keep yourself safe, informed, and updated. The Quint is now available on Telegram & WhatsApp too, Click here to join.