My 09 TG had the front ACR. Auto Compression Release back out. Sounded like exhaust leak from header pipe or tappet. Was getting louder and also getting decal pop. Took it to the dealer was ACR fixed under warranty. That was in 09 Trike had 150 miles on it back then.
An air cool Harley has a little tappy noise. Pull your self fwd and get you head in front of the tank and it's even louder but normal. A lifter that leaked down or has trash in it makes a sound like the motor is going to blow up.