Here's an interesting one for you...

[Vard66]

On Friday, the ZXR refused to start. Moreover, she refused to even turn over, deciding instead to simply make a noise like... *thinks*
y'know those wall timers, that you plug into mains sockets? She made a sound like one of those that was being forced to turn really fast, a really fast, almost buzzy, ticking noise.
While she was making this noise, the tachometer was rising jerkily, but there was no other effects to my pressing the starter button, just jerky movement of the tacho needle, and this buzzing noise.
As far as I can ascertain, this only happened when she was upright, and when I put her back on the sidestand, she turned over and fired up.
The ignition lights, as far as I recall, seemed to blink on and off at random, whether the bike was upright, or on the stand.
It happened yesterday, too, which alarmed me, as I was already late for work.

Now. Ponder that, ladies and gents.

[rover220]

start solenoid/relay? bad earth? start switch contacts?

[RedexRobB]

Flat battery.

[zimm]

flat battery .. probably low on water which is why leaning it over brought it back to life.

[steve87]

i am with zimm on that one, dont forget its a wet battery!

[masterofinsanity]

deffo sounds like the battery mate.

[Vard66]

when I put her back on the sidestand, she turned over and fired up.

Does this not dispell the theory of the battery though? I'd ridden pretty hard on the way to airsofting, so there's no way she'd not charged the battery enough to at least turn over when I started her again about an hour and a half later...
It just seemed that the position of the bars, or the orientation of the bike affected whether or not I just got solenoid noise, or an actual turning of the starter, which I thought was pretty damned odd.
I did initially think battery, but then the lights all blinked on again, and then she turned over normally, so I shut the engine off, and stood her up again, and it just buzzed again when I pressed the starter, then once more, stood her on the stand and she turned over and fired.

[zimm]

if the electrolyte level is low, the battery cant give you any power .. moving the bike around could have levelled the electrolyte out to a point where the battery functioned.

Emma's bike keeps boiling the battery dry (well, its done it 3 times in 5 years, last time was last week), .. it was dead.. wouldnt start .. just got a buzz.. didnt charge it, just filled it up .. started fine ..

on the other hand, you could have a loose connection somewhere .. I once had a SRAD 750 in the workshop where the loom had been rubbing on the frame and worn through the insulation, gave weird symptoms for about a week, then started smoking occasionally, eventually set fire to itself. I remade part of the loom and re-routed it and it was fine.

check the battery, then check the loom if the battery is all ok.