well, judging from his first post...
"a nieghbour gave my son his pocketbike. It was not running. I changed the plug and got it going. It will run as long as you have the wheel off the ground. When you put the wheel down to ride it it dies. Any suggestions?"
I'm just spitballing here ... its a Cag... And if its a w/c, you'v definately got some clutch issues!!