well the flywheel that was on it was actually lighter! but i fitted your one as the other one had loads of heatspots and some little cracks on it....i think it had a mk2 fly fitted, as it dident seem to be machined, heres a pic of a normal mk1 your lightened one and the one which was on it(i'm presuming a mk2 as ive heard these are lighter??). on my shitty scales the mk1 weighed 12kg lightened mk just under 10.5kg and the mk2 10kg
