Weird Clunking Noise!!!

[penzoil11]

Hey everyone, my gs has started to make a new noise and its really getting to me.  When I'm slowing down at lower speeds while the clutch is engaged the bike starts making what can best be described as a clunking noise every half second or so.  The bike does the same thing as I start from a stop although it's harder to hear since the engine is in gear.  I was recently trying to locate the sound as well as do some regular maintenance so I took off the chain/sprocket cover to clean out the chain grease gunk buildup.  I used WD-40 to get it clean and decided to spray some on the sprockets and chain to see if that made any difference.  The bike instantly ran like new and I no longer heard any noise... unfortunately, the noise has slowly returned and so I wanted to get some suggestions as to what it could be.  My bike has 22,000 miles and I am the original owner.  I replaced the chain about 6,000 miles ago so I don't think that's the problem. Please Help!

[ohgood]

your chain is done. or just out of adjustment. i got 24,000 out of my original.

typically the chain will get clunky at low speeds when you need to adjust the slack.

check it