Charging problem -1993 R80GS

[nud1e]

Went off for a meet Sunday, on route noticed the tacho acting funny. Stopped and found the new battery almost dead. Not enough voltage to turn starter, neutral and oil pressure lamps lit but not charging lamp.
Bump start and turn around and head for home, about half way and dead as the dodo.
Kind gent give me the use of his battery charger and a cup of tea and 90 mins of charge got me home, just.
Bike in many pieces, charging lamp OK, fuse OK, neutral lamp and oil lamp on same power supply and both were working but now the oil pressure lamp won't work, though lamp is OK.
Chased the charging lamp circuit back thru voltage regulator to diode board and no breaks. Changed the diode board for a known good one and no joy, R75/6 now in more pieces than before.
The day has long gone, the Bank Holiday wasted, fingers, hands, face and nostrils black with dirt and oil. The head is well scratched and I need serious help.
The charging lamp energises the alternator, so can't measure output. diode board, regulator.
What am I missing, what should I have checked?
Aidez moi. mes amis.

 

[Frank Warner]

Yer problem is too much alcohol

Try the rotor (open circuit), rotor brushes (dirty, not making contact) ... yer aint been around long not to know what to check... If neither of them are a problem then the (blue?) wire that runs from the headlight to the regulator maybe broken...

Oil pressure lamp .. the oil pressure switch is under and behind the left cylinder .. short the wire here to earth and check that the oil light comes on - if it does you have a faulty oil pressure switch - these are the same as used on old VW beetles.. if it does not you have a fault somewheres between the place you connected to earth and the lamp.. check at the lamp end that shorting it to earth makes the lamp light...

 

[nud1e]

Thanks Frank

the rotor is open circuit and a replacement is on the way.
Hindsight is wonderful, as I now realise that the charging light hasn't been lit for some time.
I'll have to do a proper pre-ride check from now on. It's true that familarity breeds contempt.
Now to check the oil pressure switch which has just stopped working.
Airheads - hours of endless fun, only some of it on the road.

 

[nud1e]

The bumblebee buzzes again and rattles

The continuing Limerick epistle according to Nud1e in which we discuss the physical and metaphysical joy and sorrow that is the lot of Airhead owners.

Oil pressure switch. I swapped switches with the R75/6 and light was restored - note to self, order an oil pressure switch.
Rotor - pattern rotor received from Motobins and installed and lo the charging light was restored.
12v 3W lamps for the warning lights are impossible to locate, the ones supplied from Motobins are the larger capless base, so 12V 1.2W lamps installed in the two indicator position and the 3W lamp that I didn't break put somewhere that I've already forgotten.
Fairing - the memory is too painful, let us not take off the fairing again. Better let us trade the BB for a Basic.

Finally, the work was complete and all was well.

NOT

A changeling pig has been put in place of the BB. The handling was shite, the engine asthmatic and hesitant and something rattled.
So let me think.
New tyres, new forks seals and oil, new rotor, new battery - what we need is a new owner.

The tyre fitter couldn't/wouldn't balance the wheel, so out with the pads and spin the front wheel. A little weight added and the balance seemed restored.
Off for a spin around the villages and something rattles but not my teeth or the bars. Engine still hesitant and seems to misfire.

Balance gauges on carbs and major adjustment required to tickover and sync.
Plugs swopped and timing checked with strobe.
The pig is gone but a rattling BB is back. The annoying but intermittent rattle is traced to the floating disc.

Question. Does the floating disc rattle or is a replacement required.
Answers on the back of a large cash donation gratefully accepted.