1983 Honda 250 XLR Electrics help.

Birdie

Well-known member
Subscriber
My 250 XLR side light works from the battery when the ignition is switched on, no problem, the headlights only work when the engine is running, presumably direct from the generator through the reg/rec, the battery is charging at 13.8 so the reg/rec seems to be ok but I keep blowing headlight bulbs, I have tried to get a voltage reading from the bulb holder with the engine running without any luck, when I put a new bulb in it gets very bright when revd as if its not being regulated. Any sensible ideas as I don't want to swap it for WATSITS.
 

Derek

Elite Member
Subscriber
What year is the bike? I'll see if I can get hold of a wiring diagram. Many of these bikes with direct lighting had no regulator but depended on the wattage of the various bulbs to balance the output of the generator. Is the headlight bulb the correct wattage? It is usually possible to convert them to use a modern rect/reg and run the headlight from the switched ignition but may mean making changes to the alternator wiring.
 

AirCon

Resident Thermodynamics / Electronics specialist
Subscriber
My 250 XLR side light works from the battery when the ignition is switched on, no problem, the headlights only work when the engine is running, presumably direct from the generator through the reg/rec, the battery is charging at 13.8 so the reg/rec seems to be ok but I keep blowing headlight bulbs, I have tried to get a voltage reading from the bulb holder with the engine running without any luck, when I put a new bulb in it gets very bright when revd as if its not being regulated. Any sensible ideas as I don't want to swap it for WATSITS.
Clearly that voltage isn't being regulated as it should be.
I've manage to pull up some very low res wiring diagrams and these appear to show the feed via a regulator device to the headlamps.
I'd suggest this has either failed or is incorrectly wired.
Or that the output is proportional to the total load.
Have any of the bulbs be replaced with LED and/or the incorrect wattage.
 
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AirCon

Resident Thermodynamics / Electronics specialist
Subscriber
What year is the bike? I'll see if I can get hold of a wiring diagram. Many of these bikes with direct lighting had no regulator but depended on the wattage of the various bulbs to balance the output of the generator. Is the headlight bulb the correct wattage? It is usually possible to convert them to use a modern rect/reg and run the headlight from the switched ignition but may mean making changes to the alternator wiring.
1983 see title.
 

Birdie

Well-known member
Subscriber
Nothing has been changed, the same headlight bulb has been in for years, jjust recently it blew I didn't notice as I don't ride at night and the side lamp is on for daytime riding, I only noticed when getting ready for it's MOT, I fitted a new bulb and as soon as I revd the engine the bulb got brighter and blew, I have ordered a new bulb but won't fit it until I get to the bottom of the problem, the bulb is a PX15D 35w X 35w headlight and dip.
 

AirCon

Resident Thermodynamics / Electronics specialist
Subscriber
My Brothers Husky was the same. Front and rear/brake lights only come on when the engine is running.
Tried to fit an LED bulb and it blew it within minutes.
Can you put up the appropriate wiring diagram?
Can you confirm all the wattages are correct for the year of the bike.
 

Birdie

Well-known member
Subscriber
Have looked at a wiring diagram on Google and it looks like there may be a resistor in the headlight circuit.
 

AirCon

Resident Thermodynamics / Electronics specialist
Subscriber
Have looked at a wiring diagram on Google and it looks like there may be a resistor in the headlight circuit.
That's probably the lamp?
NrouO.png
 

Birdie

Well-known member
Subscriber
Looking at that diagram it looks like power goes straight from the alternator to the dip switch, if so what regulates the voltage.
 
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