Keeps blowing Lo-beam

[rossm]

Pants! changed the bulb yesterday, went out today and the Lo filment lasted about ten (10) seconds before blowing again. Hi-beam is fine and had to ride with it on coming home tonight.

Any ideas as to what maybe causing this at all?

[bobh]

Possible things:

1. Regulator - check voltage if you have a multimeter, If not, see if the brightness of the headlamp changes noticeably between tickover and normal riding revs (say 3K upwards). This might indicate that your battery is overcharging too, so if you can rig up an ammeter to check the charge rate that would be good.

2. Loose or corroded connection to battery (either side), allowing voltage in rest of system to go high (battery normally keeps the voltage around 14v at normal charge rate). Neither of the above would explain why the dipped beam blew when full beam filament seem OK, though.

3. Dodgy connection between the dipswitch and dipped bulb filament (most likely in the switch or the connection to the bulb itself, or a connector in the wire, if any), causing current to surge. This would probably be noticeable as a flickering of the light output, unless it was happening at a very high frequency.

4. Or maybe it just happened that the replacement bulb was faulty?

Good luck - Bob