If you have the back cover off this is easy; you can get a view of this through the timing inspection port with a little mirror if the engine is in the bike, though it is more challenging…. and if you do that, you’ll be viewing things upside-down. We have a write-up on using a mirror or borescope to view it on this page. The cam chain tensioner is on the right hand side of the engine, above and to the right of the flywheel.
For a broader look at the tensioner setup, see our article here.
This cam chain is at the end of it’s life, determined by the hole/slot being visible below the tensioner bolt and not visible above it:
An example of the gap you might see with a new chain:
Part-way through it’s life:
This is the absolute limit of how much slot can be exposed – the chain should have been changed before now:
Remember if you are viewing it with a mirror that you are looking at the underside of the bolt. This means that slot visible = bad, no slot or slight amount of the slot visible = good.
To my (conservative, mechanically sympathetic) mind if you can see the straight part of the slot (i.e. the entire round part is visible below the bolt and you can see the straight section beginning) it’s time to think about changing it out.