Is my alternator on the way out?

[Caerleon]

As part of the continuous investigation into my engine running problems i replaced both injectors with pristine new ones tonight. It certainly feels alot smoother and responsive than before and less lumpy. But now the charge warning light comes on and off at idle where it didnt before? Also, it feels like the bike is back firing as i get knocking from the rear of the bike.

 

I have checked the alternator output on my bike and it reads within limits i.e. i get 13.8 v charging and the battery is usually at 12.8 before i turn it over.

 

Could it be an issue with the charing system?

 

[dirtrider]

Evening Caerleon

 

It's difficult to say if your alternator is going out. At 13.8 volts output that part seems to be OK (at least during the time that you are checking it)

 

Assuming that your charging light is functioning correctly (might not be) & your idle RPM is up to specs (might be low) then you might have an intermittent in your alternator.

 

Basically your charging light is wired to have ign switch controlled system (basically battery) voltage one side & the alternator output voltage on the other side. So when one side goes low that gives the charging light potential so the light illuminates due the potential difference.

 

What that means is IF the alternator is not putting out enough current@voltage that side goes low so the system voltage on the other (system) side of the charging light brings the light on.

 

That can also work backwards--IF the alternator is properly charging but the "system" side of the charging light is low (bad power connection or the like) the light can still illuminate due to other things on the system side creating enough load to cause a potential.

 

SO--

 

Check that fuse #1 is OK & not blown (does the neutral light work?)

 

Does the charging light come on with key ON engine OFF? It should-- (this might lead us to a side to look at)

 

Make sure the wire coming from the alternator D+ (blue wire) is not shorted or pinched to ground.

 

Make sure the engine idle RPM is at spec or top of spec.

 

Make sure the alternator belt is tight.

 

If all is right with the bike side of the charging light circuit , the engine is idling fast enough, then you might have a shorted diode in the alternator or ??? in the alternator.