Remember the Kawasaki AR 80. That thing could shift! I also heard of okes boring out the RZ 50's and sticking in a KX 60 piston.
Had an AR50, but unfortunately no photos. Got an 80cc conversion, bored that out to fit a KX80 piston, ported it to the max, reamed the read block out to take a KX80 reed valve, fitted a KX125 carb, had a special pipe built and tuned it to run on methanol.
I won’t mention here how fast it was. Nobody will believe it anyways, but those who want to know can ask Moereloos. He knew the bike well.