1952 500 cc BSA ZB34A competition. 23 HP. Plunger frame, IMHO the second worse rear suspension design the worse being the sprung hub triumphs. I was 13, it was 11. I traded my bug go-kart with a mac10 for it. When I got it, it had only 3rd gear of the four speed. Hard to get it going by using the clutch, easiest method was to point it down a hill first. At some point I figured out that the tranny case had been split open (big crack) by the lay shaft. So, I came up with a bunch of big ideal screw clamps and screwed them down and closed the crack. Now I had 4 gears. Unfortunately, I didn't pack it with grease and any oil put in would end up on the rear tire, so I ran it dry. Didn't last long and man did the transmission generate swarf in it's demise. These have a compression release and cable operated ignition retard. I have a scar at my hairline from forgetting to retard the ignition while attempting to kick start it. It spit all my 140 lbs over the bars. Eventually I came up with a transmission. Then the motor (which never broke surprisingly) got goldstar cams. Not having enough money to buy both initially I bought the intake cam by itself which as I remember really cracked the parts guy up (BTW for the really old guys on the forum the parts guy was Jim Rice the flat tracker). After installation I realized the comedy having made the motor really cammy. With both cams replaced, long reverse cone megaphone and velocity stack it made decent power. The motor eventually got put into a later goldstar swinging arm frame. Rode it constantly until I bought my first car at 16. For the life of me I can't remember who I sold it to or when exactly, but it had to be before I had the forty inch twins.