I bought a 2004 Kawasaki Vulcan 750 about 2 months ago; a few weeks ago I began noticing some noise that I wasn't expecting. It's metallic, kind of like a spring vibrating fairly hard (though I don't think it's actually a spring). It seems to happen primarily when the engine is slowing down; when I first noticed it, it would happen when I'd released the clutch and gas to shift while I was speeding up, say, to get on the highway. I've noticed it only happens after the bike's warmed up decently (needle's nearing the middle of the temp gauge); it only happens when I'm moving, though it happens whether or not the bike's in gear & whether or not the clutch is depressed (I believe it happens whether or not I'm braking, but I don't remember for sure now).

I doubt it's relevant, but I had to take off the gas tank and tighten a loose hose clamp a week or so before noticing this.

I'd much appreciate any ideas as to what this might be (or if it's even a problem).
Thanks!

 

Welcome to the forums!! Congrats on the Vulcan......

So, am I getting this right? The vibration sound only started AFTER you removed the gas tank, right?
How many miles on the bike? and when was the last oil change?

 

Thanks, it's pretty nice besides this annoying noise.

Yeah, it started some time after that. I took off the seat, gas tank, and a plastic harness on the front that just seems to hold reflectors. I've checked the all the bolts I remember removing, and they all seem tight. I THINK it's just a coincidence, but I mentioned it just in case. (btw, it was a coolant pipe - a hose clamp had worked itself loose and some coolant was leaking from the joint. But it was at least a week after I did this that I noticed the noise.)

Currently, I believe ~1700, there were slightly over 1500 when I bought it.

Unfortunately, I'm not really sure when the oil was changed.