Please Help Someone...., my 75 cb250 has developed a problem with the cam chain tensioner which has left me, my brother and my old man confused....PLEASE HELP ANYONE...we´re in the process of getting this thing ready for racing(!! yes it´s true) and have discovered that when the rear tensioner is fitted into it´s top and bottom ´cups´ and tensioned the chain is still quite loose.We don´t think the chain has stretched that much nor the tensioner itself. It´s almost as if the tensioner needs to be another 10mm longer. When the tensioner spring is released thus ´squeezing´ the tensioner and pushing it against the chain, the bottom cup comes up and there´s a tang on the cup which registers with the casting preventing it from coming up any higher...is this right?