Motorcycle Repair: Tapping sound in my engine, heritage classic, lifter

Question
QUESTION: I have a heritage classic 06 with 51k miles on my motor. it is not fuel injected. this past weekend i went for a ride and after i got back i hear a loud tapping noise that appears to be coming from my engine. I have never heard anything like this in the past. it actually sounds like metal parts tapping each other. do you have any ideas what it might be? what i might need to do about it? How serious is it. It appears to go away as i accelerate and sounds louder during idling.

ANSWER: Which side of the motor is it coming from?
Mike

---------- FOLLOW-UP ----------

QUESTION: it sounds like it is coming from the right side of the bike the side where the brake and throttle are on.

Answer
That tapping you are hearing is a lifter. When your bike goes to idle it looses a little pressure. When you rev it up, it pumps back up. In order to stop the tapping you would have to replace the lifter.
You will get to the point where the lifter does not pump up and it will rattle like crazy and the bike will run bad
Good luck and happy riding
Mike