i have the lifan 110cc and the lifan 138cc
ive had no problems with the 110 an ive been giving it a hard time
ive only had the 138 for a few days an it feels just as strong as the 110
mate of mine has a 125 lifan in one of those torque bikes and the actual engine block 'metal' tore like cardboard when his chain came off, bunched up and got caught in the engine..