I too bought and extreme scooter, 49cc and everything seems to fall apart.

the unit was received in poor condition.  I spent hours tightening each bolt and nut.  The welds are done poorly.  The muffler cracked and fell off.  The bearings on the wheels burned out and had to be replaced (lasted only 2 days).  The throttle gets stuck when you accelerate.  The brakes barley work.

DO NOT BUY ONE OF THESE UNITS.  THE ARE MADE IN CHINA AND SUCK.