first thing i did a couple years ago when i got my first puch was take a stock running e50 motor and put a mild pipe on it and a metal mesh filter and just start playing with timing carb tuning, clutch tuning, and gearing and see how much performance i can get out of it. got it up to 36. Couldn't get anymore due to previous damage to the motor that had scored the piston.
Tore that engine down and while that was going on I rebuilt a stock za50, flipped 2nd and put new pucks in, learned to reshim it properly and then tuned that.
NOW after learning that am I diving in to actually building an e50, and I'm sure I had plenty I still could have learned with the e50 had it not been damaged and cylinder/piston needed replaced.