Quick bulb question

[The Artist]

My Suzuki gs 125 rear light bulb keeps blowing.

Bought bike in january
Lights worked fine till about july ish. Rear light went, both filaments were damaged and black, glass intact.
new bulb
A few days later, it went again, but only the main light, the brake light filament still worked.
new bulb
A week later it went again, same thing, just main light gone.
Now I have just replaced the bulb again and don't want it to happen again as I have MOT tomorrow.

Fuse is fine btw
Bulb is the 2 filament in one bulb type, 5w and 21w

[Finglonga]

Check the earths and all connections going to the rear cluster. Also check the mount for the tail piece is secure as vibration kills bulbs but if you say they are black I would say it is a bad connection somewhere.
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Andy Sez....
F.Y.Y.F.F.

[The Artist]

ok, will do, thanks

[rob_scott92]

haha, weird. its like reading one of my own threads ! this happened to me a few weeks ago, i'm not sure what the problem was exactly as the unit was a bit knackered anyway so i just replaced it, and after changing the bulb that was in it, it worked fine since. i'd think its probs an earthing issue as the new unit was earthed differently to the old one if ya get me (ie, actually had an earth as part of the unit, dont know why mine didn't, some bad botching has gone down me thinks )
Just get the ol' tester out and check the earth connections and re-do if necessary.
hope all goes well
Rob

[stinkwheel]

Have a close look at the bulb. There are little wires that support the filament. Some of the cheaper bulbs have fewer of these support wires which makes them more sensitive to vibration.

If it has DC lighting (if you can turn the lights on with the engine off), you could replace the rear bulb with an LED cluster from Halfords (fits right in the slot).

If it has AC lighting (lights only work with the engine running). Were you using the full headlight or just the position light when it blew? If it blew on the position light setting, check the ballast resistor is still connected properly.

Not sure where they put the ballast on Suzukis. Probably below the headlight somewhere, its a rod about 3" long with lots of wire wrapped round it and one connector. Check the connector and make sure there is clean, not rusty metal where it bolts to the frame.
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“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[yen_powell]

Have a look at any rubber parts of the rear light mounting, probably grommets. If they harden or disintegrate you'll go through bulbs at an alarming rate.
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XT1200Z and a DR350 in bits

[The Artist]