Hi I’m looking for some help,I’ve bought my son a used tc50 and when I’ve started it and give it a little rev it doesn’t seem to want to go.ive lifted the back wheel off the floor and the wheel is turning but when it’s on the floor the bike doesn’t move.the bike did seem to start to move when I pulled the throttle right back but I didn’t want to rev it to much incase it shot off.the previous owner was a fast rider so is it possible the clutch just needs adjusted or maybe the bike just needs to warm up a bit more?