Wondering where the manual tensioner adjustment bolt is located on your Honda CX400, GL400, CX500 or GL500 motorcycle?
It’s on the right hand side of the motor at the rear, beneath the intake tube and in front of the inspection port. There may be a bottle breather over the inspection port, depending on your year/model/country. Here’s a photo with the inspection port open:

If there is no bolt found here you have an automatic cam chain tensioner.