'hree' sound accompanied by hopping?

So I got my 36t sprocket on and everything adjusted right. I started it and pulled in the clutch, and put it on the kickstand for pre-ride inspection. When I let the clutch out, it intermittently pops up and forward (just a tiny, tiny bit) while making a 'hree' sort of scraping noise. This engine only has about 15 miles on it.

What could be causing this? Thanks guys

It does go, the engine runs and drives fine-- I actually drove it a few hundred feet before I noticed the sound. I'm just worried that running it will damage the engine (or me, or the rest of the bike)

I mean the whole bike frame hops up and forward a little bit when it makes this sound (which only happens when the clutch is out) However, before I rode it any real distance I wanted to watch it run, so I put up the rear kickstand-- the style that completely raises the rear wheel from the ground. When I let the clutch out, it drives the wheel just fine but it occasionally makes a "hree" sound and the whole bike frame rocks forward and up a little bit. The movement is only noticeable when I'm not sitting on it; the sound is what initially concerned me. I think the two are related.

FWIW, it's a really awful sound. Kind of like a 4-stroke without oil-- but I'm running 24:1 for break in. Thanks for the fast reply!

Okay, many thanks! Sounds like it's no big deal. BUT, it didn't make this sound a few days ago with a 44t sprocket. And it does it randomly after I let the clutch out, not just once right as I let it out. I'll throw some grease on it and see how it does then-- maybe tonight. Thanks again =)

I just switched to a grip-shift for the clutch. Takes up virtually no handlebar space, extremely convenient, and even easier to engage/control than a handle clutch, IMO. When I first put it on, I found that it slipped almost instantly because I pulled the clutch in faster than usual! =) But I have the brass lock set *very* tight right now. No more slips.

And yeah, I'm gonna deep-clean and grease the crap out of it before I ride it again. I have to wait until the end of the week to get a 1/8th half-link so I'll have plenty of time to make it work great =)

Thanks for all the advice guys =) I want to take care of my new baby... =)

PS: Toadmund, I also love beer, from lambics to the bitterest stick-a-fork-in-it-and-it-stays beer =) I was just thinking I wish I could combine my motor-bicycling interests and beer-lovin... too bad we both picked conflicting hobbies, eh? =)