Motorcycle Repair: cb550 cam chain adjustment, honda cb550, compression stroke

Question
i have a 1975 honda cb550 and the cam chain is slappping around
inside. i need to adjust the tension screw but dont know how.
thank you for your help
z

Answer
Zack, if the chain isn't totally worn out from whipping around in there for a long time, you can make the adjustment at the back of the cylinders. Take dyno cover off so you can turn the motor with a wrench. Get the crankshaft turned so it is about 15 degrees AFTER TDC on the 1-4 cylinders with the left side (#1) just past compression stroke. Theoretically, that should put a little slack on the back side of the chain, then loosen the locknut and just turn the slotted screw back and forth a bit. The tensioner is spring loaded, so should snap into place if the parts aren't broken from the flailing around in there. The good/bad part of these bikes is that you can pull the top end with the motor in the frame, if necessary, including the tensioner parts. Bad part is that the camchain is endless and normally the motor has to be torn down for replacement. Some people have put a masterlink in the chains as a shortcut, though.

You can recheck whether the tension is correct, but turning the crankshaft back and forth with a large wrench and "feeling" whether there is a lag between moving in each direction. If so, the chain is still loose. You can also take a valve cap off, watch a valve open about half way, then rock the crankshaft back and forth and observe if the valve is opening/closing in synch with the crankshaft motion.

If you have a lot of aluminum speckles in the oil, then the chain has been rubbing against the block internally, which isn't a good thing. Steel flakes could be tensioner parts getting ground up. Check the oil filter.

Bill Silver