Won't start.

[pointer2null]

Symptom - like the battery is flat - won't turn over/turns over very slow
Counter-symptom - lights are bright and don't dim when trying to start, battery on charge overnight
Other points - can hear starter solenoid clunking/engaging.

I can't decide if this a a duff battery (quite possible as it's old and been unreliable for some time), or an electrical issue (solenoid, corroded connections, starter brushes).

Any suggestions?

I haven't got a spare battery so can't test with jump leads etc.

[red98]

+1 for battery 

[Lawrence]

If the battery was dead I'd expect the lights to dim when you cranked it.  At the same time the starter died on my Mondeo recently and behaved as if it were flat (slow cranking followed by relays clicking) but no other symptoms; lights were still bright and jumping it off another car had no effect.
 
Try and jump it or use another battery if possible.

[humbucker88]

Test the battery with a multimeter to see if it's busted

[Dead Eye]

Could the cable to the starter motor have been damaged / corroded in some place as to increase resistance and prevent it from cranking?

[riz]

If the battery was dead I'd expect the lights to dim when you cranked it.  At the same time the starter died on my Mondeo recently and behaved as if it were flat (slow cranking followed by relays clicking) but no other symptoms; lights were still bright and jumping it off another car had no effect.
 
Try and jump it or use another battery if possible.

Same with mine on a cavalier, as dead eye says could be cables/connections as well, but best bet it to jump it, or charge the battery for a bit see if its that.
How long since it was last run?

[pointer2null]

yesterday 


Was on charge all night.


I think I'll hold on getting battery and check the wiring/solenoid. Hopefully that will show the issue and I won't need to pull the starter apart.

[carrier]

Or just connect it to the car battery and see what's happening

[pointer2null]

That's the problem - I haven't got a car battery.

[carrier]

That's the problem - I haven't got a car battery.

hookup a few thousand potatoes?

[Fazerider]

It certainly doesn't sound like the battery.
Check things like the earth connector for the engine as well as those from the starter solenoid.
If you have a multimeter, measure the voltage between the terminal on the starter and the body of it when thumbing the button. If you only get a few volts, then the problem is in the supply connection, if you get full battery voltage the fault is internal to the starter motor itself... probably brushes or dirt on the commutator.

[pointer2null]

Confirmed it's not the battery. Managed to get a friend to bring his car over and checked with jump leads.

[Gimbal]

Confirmed it's not the battery. Managed to get a friend to bring his car over and checked with jump leads.

I had the same problem a few weeks ago.
Bike hadnt been ridden for a while and the battery needed charging.
Left it charging overnight and it just didnt want to start.
turned over (slowly) but wouldnt fire.
Fixed with a liberal spray of WD40.

Runs fine now.
Think it had just got a bit cold and damp.

[pointer2null]

Meant to post an update - swapped the starter with one from the breakers and it's fine now. Took the old one apart and the brushes are worn out.  Starter from breaker £45, brush set from Yamaha £39.40 + vat.