Hi all. We recently bought one of these 110cc Chinese Atv's off Australian Ebay for a 9 Year Old. About a week ago the timing chain  (Starter Motor Chain) broke, i have received a replacement one, my question is How on earth do you put the thing on ? I cannot unlink the chain & it wont go around the sprocket without removing it, but i cant remove the sprocket either because it turns when you try to unto the bolt in the center & there is no way to hold it. Any advice would be appreciated.

Thanks - Rupa  

use a 3/8" or 1/2" air impact wrench, impact wrenches will give inline torque so their's no need to hold the gear when loosening the nut.