that what happens when you lighten bikes like ktm you risk parts breaking , if i bought one , i find out the weak spot make some gussets and strengthen it, if it the clamps get aftermarket, i remember the 1980 kxs were breaking frames and i saw somewhere kawi had a gussit kit avaliable for this model , which you had to fit . going by what i read at the time they did replace broken 1980 frames with 1981 frames , i seen a few late model yz frames crack and the dealers just replace them , they reckon they didnt weld the alumiunium right just down from the head tube,
