It's a good idea to break that 8mm bolt loose before you unbolt the tensioner. Sometimes they can be real tight and it's hard to hold the tensioner to loosen the bolt if the tensioner is already off.Welcome to the forums! Be careful with the tensioner when installing it you will have to retract the plunger that pushes against the the camchain it takes a small screwdriver through the hole where the center 8mm bolt is you will have to hold the screwdriverinplace while installing the tensioner back into the motor if you let go of the screwdriver the plunger will go back out.