[I bought RE classic 350 at April 2016 and till date RE is running up to 15,860 Kms-Feb 2017] based on these days experiences I may saying the content below, to reduce the vibration in a better level.
Handle vibrations Royal Enfield
1. Max Gear we have to surely run from 50km Speed and above, but try to run within 100km Speed.
3. Maintaining the tyres pressure : Front wheel 20 or 22 PSI / Back wheel 30 or 32 PSI.
4. Usually we will be good at free services and My suggestion is after 15,000Kms we have to reach the service station at each 3000 kms without fail. RE will be good when we go for proper checking
5. Rare but linking and connecting the handle bar by Iron rod [with bolts] to reduce vibration.