Got a clanging noise coming from the motor on the primary side when hot but can't isolate it. I originally thought it was the pipe hitting on the cover but I don't believe that's it. Could it be a loose exhaust valve?? 1967 Bonneville T120
Could be the primary chain...either the tensioner has broken or the chain needs adjusting/replacing. The latter is not likely unless high mileage has been done on the chain as they are duplex and run in an oil bath...albeit that most of that may have leaked out. You will want to get to it asap as the chains have a horrible habit of wearing the cover away.
Underside of the cover should be a bolt with a locking nut. Undo the nut and turn the bolt to take up the slack....dont over tighten it. The adjuster has a rubber face that can detach so it may be that. If so the case has to come off to access the adjuster. FYI the case oil level is checked either by a stand pipe underneath or a small cover wherby you stick your finger in to feel for the oil level....or later models had two covers....one for filling and one for setting the level.