I am currently building an MZ ETZ250 trail bike as presently doing the cycle parts. However the lack of torque when used as a trail bike has to be faced. A chap came around yesterday, and by chance he’d owned a number of MZs. He said simply fit a larger rear sprocket but whilst that would alter the gearing, the lack of torque would still be there. I’d be interested to hear from others who have solved this. a 1mm head gasket perhaps?