[uncle nick]

Hi all, my XL250S has started blowing the dip filament as soon as it is turned on. The main beam is fine with no issues.
When I checked with a multimeter I found the white wire has continuity to earth when the lights are switched on.
Has anyone any ideas what might be causing it or what to check next?
Thanks in advance.

 

[uncle nick]

Re: XL250S Headlight blowing bulbs

I've been braving the arctic temperatures and have found that dip and main beam (white and blue wires) are showing around 20 volts, which must be the reason for the bulbs blowing.
I'm thinking that main doesn't blow as there's the idiot light that drops the current or as the main beam wattage is higher, the filament can take the excess voltage better.

I've been trawling the internet and it seems earlier bikes had a resistor to drop the voltage but I can't find one in the headlamp shell or on the diagram. There again, it isn't mentioned in the Haynes manual for the earlier years so who knows?

Does anyone know if the regulator/rectifier under the tank is involved in the headlight circuit and how to test it?

I found this: Honda XL 250 SA 80-81 Regulator Rectifier - by Electrex Parts at Wemoto - The UK's No.1 On-Line Motorcycle Parts Retailer but at £66 I don't want to buy it if I don't need it.

I also found this: https://www.ebay.co.uk/itm/HONDA-XL...LOWING-B701-/362183651009?hash=item5453d3eec1 which may be exactly what I need, except it sounds like an add on to fix the symptoms and I'd prefer fix the original problem and cure the illness!

I've also tried to find a local and good bike electrician but it appears you can have local or good but not both... unless anyone can recommend anyone in the north east?

 

[uncle nick]

Re: XL250S Headlight blowing bulbs

Well I called Rex Caunt. What a gentleman! Extremely helpful in wanting to learn more about the problem and solve the issue.
He suggested that as I had 20 volts that wanting to drop it to the original 6v may be asking too much of the unit, and offered a similar regulator that drops the voltage to 12 volts.
This opened a range of options for the bulbs. I ended up getting 35W/35W Halogen bulbs that are the same wattage as the original but a far brighter, whiter light.
The unit is simplicity itself to wire. There's a ring terminal that is earthed, one bullet connector that goes to the on/off headlight switch and the last wire goes to the feed from the alternator. I mounted the unit next to the existing voltage regulator/rectifier (that isn't a part of the headlight circuit) under the tank.
For some reason the pictures need rotating clockwise but I'm sure you get the idea.
Another headache fixed!