Chains aren’t cheap. Plus, they’re a pain in the ass to replace since you’ll need special tools to replace chains that don’t have a master link. You can avoid this by knowing when to replace it vs. tightening it.
Start by making sure the chain is adjusted properly. Check the owners manual for the proper amount of slack. With the engine off and the bike in neutral, find the midway point of the chain between the front and rear sprockets. Push up on the bottom of the chain and make note of the distance between the full-slack (lower) position and the no-slack (upper) position on the bottom.
If there’s too much or too little slack, you’ll have to adjust the drive chain – usually by loosening the axle nut a couple of turns then make the adjustments noted in your manual.
Once the chain is properly adjusted, grab the chain with your your thumb and forefinger at the very back of the rear sprocket. You shouldn’t be able to lift any chain link more than about halfway off it’s sprocket. If you can, time to trash that chain. But wait, there’s more.
If that chain is toast, your sprockets might be right there with it. Check both front and rear sprockets for any hooked or wavy appearance. If you put a new chain on worn sprockets, you’ll soon be putting on another chain. And vice versa.
So get the whole thing taken care of and be done with it.