In the 1990's.
I was 12 and a friend had a yamaha 50 frame and another friends uncle had a Honda 50 engine.
Jimmyrigged the engine in. Connected the throttle cable to the front brake as it had no throttle twister on it. Didn't bother with the front brake, it had a back one after all.
Exhaust pipe was held near the exhaust port by string and baling wife and one chain tensioner was missing so there was a small vice grip holding the axle straight on the chain side.
We used to take turns blasting around country roads on that heap, and stretch cable on the blind side of bends to catch the unwary and lift them off the bike as they went. . .
No helmets and I can't remember anybody even getting a decent scratch!