New to motorbike world--Help with brakes!

Hi I'm going to be posting from time to time for advice and questions. I've never built a motorbike before so thank you before hand for any help. I have a newer model schwinn stingray-krate frame and I have a question about the braking system. My goal is to get an 80cc engine to fit on it and I'm most likely going cut the frame and mod it a bit. My question is, what should I do about the braking system? I mean is there any alternative more improved parts for motorbikes to make it safer when going higher speeds and decelerating?

Thanks a lot everyone I'll look up what you've all suggested so far. My only concern with my bike is it's got no gears, and one simple braking method, I hold back on my pedals and my back tire brakes. So I should definitely look into a front brake.