MDB I have alot of riding experiance, I race dirtbikes and have been doing it for about 13 years. Im no expert on minibike motors though. My gearing hasnt been changed since I swapped the motor but the briggs and clone have a hole different bottom end power delivery. The motor was probably reving out to 5500 or so it had alot more left in it but I backed off, I thought it was strange though that it would rev that high when it still has the gov?
It's just the gearing scaring you
It's makes you think the motor is screaming, or the bike seems to be out of control with so much power.
Dirtbikes are totally different from minibikes. I have let guys fun ride my slowest minibike, only to crash on it. And these guys ride motorcycles, and dirtbikes.
What you should do is totally remove the govenor, and install a billet rod. Be safe, and have fun.