I had one of the first 2004 tickers Yamaha ever heard of - they sent my whole cylinder head back to Japan for study. Yamaha replaced the head, but the second one ticked too. I got a second repair, this time with the new valve guide seals, and I've been tick-free ever since.
Here is what I tell people who think they might have a ticker: ignore it for a while.
If there is any doubt, then you don't have it - not for sure, not yet. The ticking gets worse over time. If you really do have it, you'll know for sure about 4K or 6K miles after you first thought you might have heard it. By the end of 6K miles it should be unmistakeably loud: if people in cars next to you at stoplights are not turning their heads to see where all the racket is coming from, you don't have a ticker.
Besides that, yes, you should think "cam chain tensioner," especially if it's louder on the right than the left. The tick has historically been louder on the left. Also, the CCT is pretty cheap and easy to check/fix, and Yamaha's diagnostic procedure is to do that fix first in any case.
The definitive diagnostic is to remove the four exhaust headers and look for stains or gooey unburned oil in the ports and pipes. A healthy engine is bone-dry in there. This procedure is expensive and a PITA so folks don't do it (or have it done) until they're pretty sure.
The best moment in my experience came when I was talking to the dealer's service manager:
I told
him what Yamaha would say when he called - that they would ask him to read back all the part numbers he was about to order for the second repair. I wish I could have seen his face when they did exactly as I said they would. Service managers don't expect customers to know more about Yamaha than they do, and he was mightily impressed.
You can read my (now pretty old)
ticker web pages from back when this was a current topic for me. Looking at it now, the page called "Yamaha's Advice for Ticker Owners" reads like the advice you'd give a domestic abuse victim: "People are more aware of this now than they used to be. Don't let your dealer blow you off: call Yamaha, and you will be believed."