Re: Motorcycle un-recovery... sort of...

In article <87tztk91ok.fsf@xxxxxxxxxxx>,
Graham Reed <greed@xxxxxxxxx> wrote:

Davide Bianchi <davideyeahsure@xxxxxxxxxxxxxx> writes:
On 2007-06-06, Michel Buijsman <abuse@xxxxxxxxxxxxxxxx> wrote:
[0] If the bulb pops, the bike won't charge properly.

now, that is a sweet piece of engineering...

Bike electrics make car electrics look sane.

And that includes a world which has had Lucas Automotive in it.

Heh. The morning bus to Ork has had some "interesting" electrical
faults of late. Doors taking 30 seconds to decide to close, the
entire instrument panel going dark, and Monday's piece de resistance:
Windscreen wipers running full time, with intermittent washer
oiperation, doors not closing, and none of the instrument panel
functional.

Apparently their "mechanics" are slowly replacing the entire
instrument panel, bit by bit, but I've suggested to the driver
"GET THEM TO CHECK ALL THE EARTH LEADS" which is most likely
to cause electrical crazyness as the return rail lollops up
and down due to loose connection(s).

The Honda ST1100, for instance, didn't grow a proper
variable-rotor-field, integral-regulator alternator until the 1996
model year.

Permanent-magnet alternators may be fine on sport bikes, but on a
heavy sport-tourer where people want aux lights and heated clothing?
And GPS and intercoms and radar detectors (where permitted, of course)
and two-way radio and... well, you get the idea.

Undersized wiring, dodgy connector quality, and corroding ground
points, are all there waiting for you. All three lead to weird
intermittent faults that are a pain to troubleshoot with any sort of
meter--looking for melted and burned connectors is really the first
thing to do. And clean and re-make your battery cable connections.

One of our firework crew recently had to re-loom a forklift truck.
Then the [deleted] bodyfitters arrived to fit guards, etc. and were
told "be VERY careful where you drill holes, as there is wiring
behind these panels: don't go more than a quarter of an inch deep".

Came back to find a dead forklift again: they had dead-centred the
main loom and put a bolt all the way through it.

For non-bikers in the crowd: permanent magnet alternators usually
feature a "shunt regulator". This is a brilliant piece of engineering
which, basically, fires an SCR when the voltage from a winding exceeds
the desired maximum. So the rest of the cycle from that winding is
shorted to ground. So the VRR block has to dump all that power as
heat. And the alternator coils tend to run near capacity all the
time, until they fail of course. Or you keeps the revs really low.

(Well, I can't find a scheme of one, so I'm going from memory. Have a
grain of salt or 20 handy.)

Medium Brother's CCN/Rotax 350cc MotoCrosser just has two resistors
across the alternator outputs. I know this because I had to rewire
the whole thing for him and derive the intended circuit diagram
and there are no plans in existence for the beast. (The factory
burned to the ground a while back, taking all the documentation
with it - very conveniently apparently: there was an audit about
to happen.)

The resistors are there to swamp the output voltage if the bulbs
(head/tail on one winding, stop on another winding) fail, to prevent
the insulation breaking down in the windings. Oh, and it's AC electrics!

Chris.

--
"George Flynn told us at Ditto that he knew he'd been in fandom too
long when he went to see THE SHINING and found himself evaluating the
hotel's function space." --Richard Brandt

.

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