Motorcycle Repair: 1975cb250k5 camchain tensioner, original chain, cam chain

Question
Okay Chris...this may be too curly for you but see what you think...
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?

Answer
Hi Chris.
 If these are the original chain and tensioners, and even if they are not, then they may need to be replaced.

Remember that this is a 29 year old bike and no part lasts forever.  Chains do stretch.  If they didn't, you wouldn't need an adjustable tensioner.  And tensioners wear out too.

Pull those parts and match them against the specs in the manual.  My guess is that you will find the tensioners worn too far and the cam chain will likely be stretched too far as well.

Check it out and see for yourself.
Good luck in your races.
FALCON