Typically, “ticking” is only caused by a handful of this:
- Worn Bearings
- Valve train play
- (Semi-rarely) Piston knocking
- (Rarely) High-voltage arcs/discharge
Of these (generally) the only ones that follow with RPMs are usually bearings and valves, relays will not (usually).
Since your troubleshooting indicates the sound is coming from the “top of the motor” that would lean toward valve train play.
Now, I will say, that this isn’t always caused by wear - some motors are just noisier than others. I recently tore the top end apart to do valve adjustment in my Kawasaki, and they were all dead center of spec tolerances... yet it still makes some noise now and then.
That said, it is possible that it’s not a design flaw, and some part is outside of tolerances. Unfortunately, the only way to be SURE is to tear the motor apart and check everything.
You can look through the spark plug holes to see if there is valve/piston knocking, but for the rockers, lifters, cams (ETC) you’ll have to first look, then measure. It may be an easily visible thing, it may not.