Measuring discs and a battery

Hmmm. Good thinking. I shall investigate

Yes please!

 

I never tried, since the time when on cylinder stopped working on my
Sprint ST. While waiting for the AA to arrive I managed to get the
tank off but couldn't even find a park plug, let alone remove one. In
the event it turned out to be a coil that had failed, and indeed it
was the very same thing that was hiding the plugs from view, as they
sat directly on top of the plug. Not much chance of 'sticking the plug
into the HT lead' there, even if you managed to get the fuckers out.

IIRC they were a 24000 mile service item. Modern FI systems rock.

 

Optimate.

 

Ah. Oh. There must be an easy way of allowing the starter to spin
without fiting the engine? I mean, the kill switch on my 400 Four and
my Ducati don't isolate the starter motor: just the ignition.

Oh, modern bikes, yeah, right.

Unplug the CDI or something? Run a cable direct from the battery to
the starter motor terminal?

 

wait, are you trying to assess whether the discs are warped or not?

Do you have a halogen hob or similar? That'll be completely flat - pop
the disk on the hob and see if there's any wobble - tapping round the
edge of the disk should produce no flapping noise or lateral movement.

 

IIRC it's an induction hob. He could lay the disc on the hob on top of a
sheet of paper, heat it up, and see where the paper charred...

 

Pull a fuse in the igniton circuit, whatever.

Then do as Speedgazebo suggested and just measure the voltage drop
when you crank it. A failing battery will struggle to supply the
required current and the voltage across the battery terminals will
drop significantly as a consequence.

 

Yup, gets my vote.

As an aisde, don't you love it when someone here posts a wonderfully
simple technical problem that's actually more difficult to solve than
it sounds? I'm surprised nobody's suggested voltage-seeking ferrets
yet.

 

That's not *quite* what I said when I did the job

I always thought that was poor design - I recall lots of Honda owners
in the 70s and 80s spinning their starter motors and wondering why
their bike wouldn't start.

Prolly the best thing would be to see how many times it'd start the
engine?

 

<pulls chin>

Y'know, that might just work! Depends on the ferrous content of the
discs, mind.

 

The optimate returns it to working order without complaint. A week
later, it won't start the bike.

 

Have I missed something, or won't you have the same problem with the
disc buttons as with the sheet of glass?

 

Champ wrote:
snip

Just buy a new one you cheapskate, I bet it's more than two years old.

 

You know that comment you made to Paul the other day about how you have
a shortage of time and an abundance of money?

Just buy another fucking battery.

 

He's probably after a more weaselly-used method.

 

It's dead. How bleedin' tight do you want to be? Buy. Another.
Battery.

(And keep the old one with your knackered discs, saggy chains and bald
tyres, in case it comes in handy)

 

Or something stoatally different.

 

All mention of stoats, from this point forth in the thread, is banned.

 

that's odd - in theory the optimate should detect that the battery
isn't charging properly.

are you sure it's the battery - i.e. there isn't something that's
causing a drain even when the bike's switched off.

Have you tried charging the battery, then leaving it disconnected from
the bike for a week, then seeing if it starts the bike (after
reconnecting it, duh)

 

I bloody knew it.