update.
I finished the bike, took the predator off and put a nice clean 3.5HP briggs on it and gave him the predator he paid me for. I gave him the bike back on his last day shift and he was upset that I had a smaller motor on it. I explained to him several times that the bike with the predator is really over powered for his kids. 2 days later he comes to work after his days off with a bandage on his head. He comes into my office and said 'hey you were right that big motor was too much power' He was riding it down the road with the predator and rolled from half to full throttle and it threw him on the ground and he bashed his head off the pavement.
He wasn't upset with me, he said you warned me and I didn't listen I just didn't see how a small motor like that could make that bike such a beast.