Where is the main earth on the chassis? its certainly a good idea, I know a bad earth on a car can cause havock!!
It almost seems heat related as well, runs fine for 5 mins, tacho goes 30 secs later bike stops. wont even turn over once stopped, neutral light barely illuminates. But leave it for over 30 mins and itds fine again, bach to step one?!
Have you checked all the battery and regulator/rectifier wiring? Really prone to melting and breaking down especially the yellow wires that come across the bike from the stator. Iv'e seen bikes displaying all the symptoms you desribe and when the wiring was checked, all the connectors were melted and the insulation from the yellow wires was completely gone for about 4 or 5 inches back from the connectors!
The main battery to earth connection is not on the frame, it's on the crankcase - look at about 11 o'clock on the clutch cover,go in about aninch past the cover & slightly above the swing arm pivot & you'll see a button headed allen bolt holding the earth lead on. They can be a total barsteward to remove. I've got some new battery leads for mine & have got to take the old ones off..... not looking forward to that!
Ive had a quick look at those yellow wires and they seemed ok, not followed them the whole way back mind. Also the alternator stator is only about 500 miles old, whether its duff?!
Managed to borrow a multi meter and a bm80 at last too so ill have a decent examination tomorrow.
Had a simular problem fairly recently, yes it was the wiring that had burnt through.
Before i knew what the problem was i recharged the battery and the bike ran for a while, had all the wiring checked out and the problem was found, happy hunting!
My SEnna used to do that, including a very embarrassing lap at the Nurburgring riders club where we were all meant to keepo lights on when at front or rear and the instructors used to go psycho if you didn't have light on. Sitaution got so bad I had to turn lights off at Bergwerk ('bout half way round) and even when I applied brake light it would splutter. (you ever tried to go round 'ring withOUT braking?) In the end it was a loose connection between alternator and regulator somewhere, so it's always worth checking all connections I reckon.
Checked all wiring, its all spot on. Resistanse accross the stator is as it should be acordig to haynes. But AC voltage is about 1/2 - 2/3 what it should be att all revs acording to haynes. With ign off batt ha 12.8V accross terminals, running its bout 11.5-11.8V, so my guess is alternator stator, must have shorted a few windings somewhere!
All earths and cable continuities spot on,
I have now had enough, I need some persuation not to go to Honda!!!