I have a 1968 K0 CB250 it is a very early engine number,( before CB250E 1004622 ) After reading up on the early engine, apparently it should have a high lift cam, Unlike any of the other K series engines. Have checked the valve timing settings using a degree disk and a dti gauge, but the timing readings I got were for the common later cam.(checked many times) I do know that this engine has not been interfered with from new, all I can think is that very few models were fitted this extremely rare camshaft.