OFF-ROAD RACER - 1963 BSA ROCKET GOLD STAR This was the end of pre-Unit BSAs & an amalgam of parts: 650cc twin engine out of a pre-unit A10 Rocket, shove it into a modified Gold Star single frame - a Rocket 650 engine/Gold Star frame hybrid. It ran great... for one year. By 1963, BSA & Triumph converted to unit construction engines & new frames, ending the pre-unit A10 engines and the supply of frames. Why did BSA go to all the trouble? These gorgeous machines are hoarded by collectors.