Ignition light comming on

canonball · Oct 3, 2006

After about 10 minutes of riding my ignition light comes on. I am assuming that it has got something to do with oil pressure but if the pump is stuffed i would have thought the light would be on all the time ?

The return of oil into the oil tank is a trickle at best so i am assuming it is the pump.

Any thoughts.

L.A.B. · Oct 3, 2006

The Commando ignition warning light works off the charging system and is nothing to do with oil pressure, it (should) show if the charging system is working properly (if it goes out?) or the assimilator could be faulty?.

canonball · Oct 3, 2006

Thanks for that. For some reason i had it in my mind it was oil pressure.

So my charging system doesn't want to be a charging system then ?

L.A.B. · Oct 3, 2006

It could be a charging system fault?
Does the battery seem to be holding a charge?
Does the headlight brighten slightly when the engine is revved from idle? It could just be the assimilator or bad electrical connection.

tpeever · Oct 3, 2006

Funny that your warning light should be coming on after 10 minutes. Does it come on when the rpms drop below 1000 or so? In my experience, this is where the standard 130W alternator cannot keep up a charge on the battery with the headlight on. Are you charging your battery on a trickle charger or battery tender before riding? If so, this might explain the 10 minute lag. I would have thought a fully charged battery would give you more than 10 minutes before dropping below 12 volts though. If you hook a voltmeter to your battery, the voltage should rise to around 13 at 3000 rpm or so. If it doesn't, your alternator isn't charging the battery sufficiently and it may be that your rotor has lost its magnetism.

canonball said:
After about 10 minutes of riding my ignition light comes on. I am assuming that it has got something to do with oil pressure but if the pump is stuffed i would have thought the light would be on all the time ?

The return of oil into the oil tank is a trickle at best so i am assuming it is the pump.

Any thoughts.

L.A.B. · Oct 4, 2006

tpeever said:
Are you charging your battery on a trickle charger or battery tender before riding? If so, this might explain the 10 minute lag. I would have thought a fully charged battery would give you more than 10 minutes before dropping below 12 volts though.

The warning light assimilator is triggered by output directly from the alternator, and does not give any low battery voltage indication as far as I am aware?

tpeever · Oct 4, 2006

Just remembered that the only time this happened to me (warning light coming on after about 10 minutes riding at 60 mph), my stator had insufficent clearance around the rotor. Presumably the warning light started coming on when the rotor warmed up sufficiently, had expanded a bit and was no longer charging. After turning around and heading for home and about 2 minutes later, the rotor seized to the stator and took out my primary drive. Expensive mistake!! I now check rotor clearance (0.008 inch minimum, 0.010 better) very carefully!!

canonball said:
After about 10 minutes of riding my ignition light comes on. I am assuming that it has got something to do with oil pressure but if the pump is stuffed i would have thought the light would be on all the time ?

The return of oil into the oil tank is a trickle at best so i am assuming it is the pump.

Any thoughts.

tpeever · Oct 4, 2006

Yeah, I think you're right. So why do you think his light would be coming on after 10 minutes?

L.A.B. said:
tpeever said:

Are you charging your battery on a trickle charger or battery tender before riding? If so, this might explain the 10 minute lag. I would have thought a fully charged battery would give you more than 10 minutes before dropping below 12 volts though.

Click to expand...

The warning light assimilator is triggered by output directly from the alternator, and does not give any low battery voltage indication as far as I am aware?

L.A.B. · Oct 4, 2006

tpeever said:
Yeah, I think you're right. So why do you think his light would be coming on after 10 minutes?

First thing (in my opinion) would be to try to find out if the problem is a 'charging' problem or an 'assimilator' problem, and I have asked a couple of direct questions already:

Does the battery seem to be holding a charge?
Does the headlight brighten slightly when the engine is revved from idle?

If the battery is staying charged then the problem could be just a faulty assimilator? There does seem to have been a few members here who have had that problem.
If canonball is able to give some answers to the questions then I think there could be more chance of pinpointing exactly what the problem is, otherwise we're just guessing?

canonball · Oct 4, 2006

Sorry lads was away for a couple of days unexpectantly.

Its a Mk3 and because of a dodgy right leg i use the Es all the time. I charged it up at the weekend and so far the ES is spinning around good style.

I did have charging problems last year and checked the a rotar gap. It was off to one side but once set correctly was much better. I used to have to re charge the battery every couple of Weeks but now...until the red light issue, was going for a couple of months.

The light doesn't go off when i raise the revs to say 3000 but the headlight does brighten when i raise the revs.

I havn't checked the voltage but will see what it is when i get home from work.

Ron L · Oct 5, 2006

"The light doesn't go off when i raise the revs to say 3000 but the
headlight does brighten when i raise the revs. "

Sounds like the battery isn't being charged. Check the wiring first. Good connections at the alternator, rectifier, and both zeners. Next I'd check the cable as it exits the potting on the stator. This has a habit of getting brittle and some "mechanics" let the stator dangle by this cable when they remove it. If this all checks out, then you can start testing the AC output of the alternator and the rectifier

L.A.B. · Oct 5, 2006

Ron L said:
Sounds like the battery isn't being charged.

There doesn't appear to be any evidence (so far) to suggest that, as the warning light assimilator is triggered directly from the alternator AC output and does not give any indication of battery circuit Voltage? So there could well be a fault in the charge circuit although as the lights brighten when the engine is revved would suggest there is (at least some) output from the alternator but could still at this stage be an assimilator circuit fault?

Ignition light comming on

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