De-lurking somewhat, especially as I now have a motorcycle of my own, finally lured to the two-wheeled-side by Melbourne friends... Since I'm mostly used to maintaining and listening to my Mk1 MR2's little engine, I have pretty much no idea what my VTR should or shouldn't sound like. Last night I noticed last night that at a few thousand RPM (but not at idle) the engine makes a "zmmmming" noise which I assume is the cam chains whirring away. The bike's only done perhaps 15,000km before it came into my hands, so I'm hoping that it's normal behaviour - but I've never heard any engine make that sound before. Is this normal for a VTR250?