Long stroke version of the 500 twin that uses many Bullet bits in its top end. In ’56 the Meteor became the 40hp Super Meteor with stronger crank and clutch, excess of torque and smoother than Triumphs. Engines can turn nasty with age. In ’58 the Constellation emerged with 50hp, featuring a dynamically balanced crank to keep vibes down. If you find one that doesn’t leak oil it’s probably a good ’un.