[pdwestman]

I can't tell much from the YT video either. I hear more whine than knock.

But I'll ask if you had the LH engine cover & flywheel OFF just before the noise started? If so, the starter ring gear may be jammed & therefore spinning the starter motor WAY Faster than it will survive.

Normally when the starter stops turning, the starter clutch disengages from the flywheel and all 3 starter gears remain stationary along with the starter motor.
Flywheel tapers MUST BE installed Clean & DRY, otherwise they may slide further together than Normal, jamming against the washers and ring gear drive stub.

 

[pdwestman]

The noise started when I was doing part of the TAT a few months ago and I decided to come home because of it. It HAS felt/sounded like the bike has been running at a higher RPM than what the tach says, so how should I go about checking the starter ring gear?

If the noise began when you were riding it & you road it home it is Probably NOT the starter clutch ring gear turning the starter motor. The starter motor would NOT have been able to survive the rpm created by highway speeds, imo.
If one uses a 19mm socket on the flywheel bolt & turns the engine in normal direction of rotation (CCW) one SHOULDN'T hear any starter noise.
But if one turns the engine backwards (CW) one will normally hear the whirr of the starter gears & starter motor being spun by the starter clutch & ring gear. Shifted into 2nd or 3rd gear and rolled backwards should make the same noise. And no starter noise when rolled forward.

But if your engine still has the OEM extension spring in the balancer tensioning system you may have an issue with that system.

Did you disturb the Cam Chain Tensioner in any manner just before your trip? If Not, then it probably is not the source of your current noise either. That tensioner has been Very Reliable when Properly removed & reinstalled.

 

[pdwestman]

Would it be possible that the woodruff key could have been bent or something causing anything to be off balance?

Only if the installer of the doo & torsion spring did something WRONG!

 

[pdwestman]

One can remove the top cap plug & spring from the cam chain tensioner & insert a screwdriver. Hold a little pressure on the screwdriver & start the bike. If the tensioner is/was functioning properly the screwdriver may barely move In & Out, or not at all. It works on sliding ratchet teeth to keep it from re-extending.

If not functioning properly the screwdriver will chatter back & forth a Fair bit.

 

[pdwestman]

Apologies, for my vagueness and confusion. I wanted to test if more tension on the chain would help so I didn't completely reset the tensioner.

So you did that before or after reading my post?
Next I suggest that you remove the tensioner, extend it and inspect the area of previous setting for the condition of the sliding bar locking teeth.

I'm thinking of getting a manual tensioner before it's put under any actual load from riding.

I would never install a manual tensioner on my KLR!

There are very good reasons that the factories invented the Automatic cam chain tensioners clear back in the 1970's.
And the sliding bar ratchet tooth design is one of the best, imo. It's spring-loaded design ensures that the chain has minimal slack, yet is Never adjusted Too Tightly.
If one click tighter made it quieter to your ears, ride it.