I dont think a 100 will suit your needs,you will be sorry in the end.Most people that ride 50s and 100s for a pitbike will beef up the suspension with better springs and shocks and better clutch.If your really stuck on having a small bike maybe look at a crf150r,they have better suspension and more seat height.Dont overlook a 2stroke either,they are much less maitenance and are way cheaper to rebuild than a 4stroke.As for a 2stroke being loud,the sound of a 4stoke travels much further than a 2stroke.