Quick Question: H4 headlight bad?

Doogie

Doogie

Been Around the Block
I have a 81' KZ440 with a Harley Sportster light that I got for free. It runs just fine, high and low beams.

Am I running on borrowed time concerning my charging system? Should I not risk it? Or would I be fine?

Opinions, suggestions, wisdom, etc. all welcome.

Thanks!!
 
xb33bsa said:
yes you're bike will be leaking oil on a trailer soon :'(
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And you can get buried with it when you pass away……


But really, the wattage of the bulb is the kicker - I think a KZ440 ran a 35/35w bulb stock?
 
I am not sure of the wattage on the bulbs. I will try to look it up or find out?

If I find out it's not right can I just swap out the bulb for the right one??
 
wattage is the key.
If you swap your tail light to an LED lamp it will help, as the tail light is on when the headlamp is and it's the combined load that matters.


LED lamps in your speedo/tach help too, as they are always on.


Blinkers are intermittent loads, so while LED's are cool in signals, they don't affect your charging system all that much.


Your stator is only capable of so much total output, and if you overdraw it, you can cook various components and kill your battery.
 
Bozz said:
wattage is the key.
If you swap your tail light to an LED lamp it will help, as the tail light is on when the headlamp is and it's the combined load that matters.


LED lamps in your speedo/tach help too, as they are always on.


Blinkers are intermittent loads, so while LED's are cool in signals, they don't affect your charging system all that much.


Your stator is only capable of so much total output, and if you overdraw it, you can cook various components and kill your battery.
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My tail light is now an LED light. I'm not running any turn signals.

Is there any way I will be warned I am frying something or will I just be surprised?
 
Unlikely you'll fry anything. More likely is that you'll kill the battery when you're idling at a stop light.
 
Sonreir said:
Unlikely you'll fry anything. More likely is that you'll kill the battery when you're idling at a stop light.
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Well that sounds like fun. So what would be my options?
Change out the bike for a 35watt?
 
Got a multimeter? Connect it to your battery terminals whilst the bike is running and check the voltage. If it's running at 13v or more with the light on you're in the clear. If it's under, then you might want to change the bulb or ride the bike more with the headlight switched off than on.
 
If you are still running the stock Reg/rec unit you might consider upgrading that component.
Modern sportbike Reg/Rec units can frequently be found really cheap and the newer technology improves your charging efficiency slightly.
If you are pushing your system load wise, that minor improvement can bring back a little headroom.


It is possible (but admittedly unlikely) that running your charging system slightly over capacity for an extended period can damage the old reg/rec unit, but as mentioned above your battery will likely be the first component to suffer.
 
I will look into upgrading the reg.

Anything special I need to look for or just a new modern unit will do?

Thanks again for all the help and for hopefully saving my battery.
 
Get a multimeter and check your current charging. You're wasting your time if it's charging OK as it stands.
 
I have a multi meter and I was going to do it today but I was working on something else. I will give it a test before I buy anything for sure.
 
You could always just switch to an LED headlamp. As you already know, LEDs have a much lower current draw and it will likely be a cheaper and easier solution than messing around with your system. Plus there's that added benefit of LEDs lasting a LOT longer than the standard halogen bulb :)
 
orrible-64 said:
hi...running h4 headlamp on my 81' ltd250 for over a year. no sign of problems yet

pete
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It's not the style of bulb that's the issue, it's the wattage. H4 bulbs come in a variety of wattages.
 
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