Bought a 1975 FLH and I am new to Shovel's and having some electrical issues that I need to sort out and hoping for some help from you guys. The charging system is not charging the battery when its running. I can get about 10-12 starts out of it before I gotta manually charge the battery again. I did that a couple of times but the last time I was riding it I notice the smell of burning wires coming from the headlight bucket, then eventually the headlight went out. I parked it and havnt rode it since I noticed the wires burning.


I know the usual suspects of not charging are the stator or voltage regulator. But with the additional info of the headlight wires burning and light going out completely, does that help narrow down the problem at all?


Unfortunatley I live in Japan and cant do any troubleshooting or fixing until I get home in September. Only gonna be on leave for about 3 weeks so im trying to get my ducks in a row before I get there so I can hopefully get it fixed in the first couple of day and enjoy a few weeks of riding.


Thanks in advance

 

The electrics on your bike are pretty simple, compared with modern bikes, so tracing your headlight problem should be easy enough. The headlight going out may simply be due to the charging system not regulating the voltage, which can climb to silly levels.

You are in the Tech Electrical section and will find two Stickies at the top, with details of checking your charging system. They will enable you to identify the culprit. Leave your headlight switched off or disconnected while testing your system.

In the meantime get yourself a factory service manual, if you don't have one, which will spell out further details on checking the charging system, plus lots more.

 

Thanks for the tips. Another quick question. If the stator checks out good and is putting out the correct voltage, then chances are the regulator is preventing the battery from charging. Could a bad regulator possibly be the culprit for both battery not charging AND headlight wires burning up?

 

My guess is that your alternator is fine, but not being regulated, in other words your regulator is knackered. What happens in that situation is that voltage climbs with engine speed, unchecked, whizzing up to great heights, hence the damage to your bulb and wiring. If that is the problem I would expect your poor battery to be over-charged, which can also cause damage to it.

So I'm not sure I can say yes to your question! That is why I recommend you follow those Stickies and test your system. I suspect your regulator is toast, but your battery may also be - but check first! Knowledge is power - test and diagnose first, then replace as required.

 

Thanks for the explanation, sir. I kinda thought that too but what confuses me is that the battery will charge up and hold a charge when using a bench charger. It goes dead after starting the engine several times. Im gonna try to find a friend with a little mechanical skills to do some troubleshooting for me. Unfortunately I won't be able to do any testing until September when I'm home on leave. I live in Japan and the bike is in upper Michigan.

 

Despite living in the UK, Mrs B and I have visited North Michigan on our Glide and enjoyed eating Cornish pasties in Munising! As for being in Japan, that's a long way from your poor bike. Best of luck sorting out when you are able to.

 

Got it figured out. A friend stopped by my dads garage and did some testing. Stator was fine but the voltage regulator was toast. He also discovered that the previous owner had the voltage regulator hooked up to the negative post on the battery for reasons unknown. Thanks again for the support.