Loose battery connections will cause spikes in the system voltage. A bad regulator could do this also but the battery <should> serve as a buffer (capacitor) anyway and not all the voltage to rise fast enough and far enough to damage anything.
As already mentioned, you should check the current the LEDs are drawing. It is not likely that a voltage spike is causing the LEDs to fail without causing damage to other components on the bike. It could also be a faulty design on the LED and they are being overdriven even at normal system voltage; 1/4 amp is a fair amount of power for LEDs unless there are a lot of them in the assembly.
Brian
I'm suspecting my bike of having a voltage surge. What components are the most likely culprits and how would I test them?
I have LED lights fitted to the bike and they keep blowing, even with a 1A fuse. Lights are rated 1/4A though so it maybe I just need a lower amp fuse to protect them, but that would mean the fuse constantly blowing. I'm tinkering with the idea of putting a voltage suppressor inline, but would rather solve the cause than the symptoms.