Speak of engine refinement, construction, vibrations of the J-Series, as we experienced with the Meteor as well, are overwhelming areas of improvement over the Unit Construction (UCE) engine.

from Times of India https://timesofindia.indiatimes.com/auto/bikes/new-royal-enfield-classic-350-review-2021-royal-enfield-classic-350-does-most-things-correct/articleshow/85823088.cms