2 Stroke 6v power surging

[Nearbymitch]

Yamaha RX125 1979. Well, here goes. I have been working on this little bike for awhile now and i had it all ready to go for a vin. I have put LED lights on wich were working perfectly fine and were not drawing too much power. I took it out for a semi decent ride around town and once i got home i realized that the right hand indicators, the number plate light and tail light were all blown. I have brought all new ones to replace them and are about to wire them all up. I have done quite abit of research on the net about this and there seems to be nothing else on this problem. I cant seem to find any 6v voltage regulators or surge protectors anywhere on the net. Is this problem just a freak thing and wont occur again? Or is there a way to limit it so it doesn't surge? Or even get it to pop a fuse before it blows the lights. Thanks in advance.

[sidecar bob]

Yamaha RX125 1979. Well, here goes. I have been working on this little bike for awhile now and i had it all ready to go for a vin. I have put LED lights on wich were working perfectly fine and were not drawing too much power. I took it out for a semi decent ride around town and once i got home i realized that the right hand indicators, the number plate light and tail light were all blown. I have brought all new ones to replace them and are about to wire them all up. I have done quite abit of research on the net about this and there seems to be nothing else on this problem. I cant seem to find any 6v voltage regulators or surge protectors anywhere on the net. Is this problem just a freak thing and wont occur again? Or is there a way to limit it so it doesn't surge? Or even get it to pop a fuse before it blows the lights. Thanks in advance.

Are you running a battery? I'm thinking not.

[Nearbymitch]

Are you running a battery? I'm thinking not.

I am not, it has a battery eliminator in it, pretty much like a capacitor. I presumed this would act the same as a battery?

[Honest Andy]

Perhaps: https://www.jaycar.co.nz/7806-6v-1a-voltage-regulator/p/ZV1506
Just a thought. At only 1 Amp max you would obviously be best to bung one on at every LED but at only $2.30...

[sidecar bob]

I am not, it has a battery eliminator in it, pretty much like a capacitor. I presumed this would act the same as a battery?

Well it's not doing a very good job then.

[motorbyclist]

Any luck?

Many older 6V bikes seem to develop issues where they blow headlights etc. They also tend to dry out batteries.

What people forget is that older bikes, before regulator/rectifiers were common, had an electrical system that was a careful balance of generation and load with a battery to take up the slack. Reducing the load, ie with LEDs, can actually cause an increase in voltage. Removing the battery, or having a dry battery, removes what "buffer" you had between the bulbs and the charging coil/s in this event.

My own 100cc, 6V beastie would slowly sputter the headlight bulb filament onto the inside of the bulb, until it had completely mirrored the glass from the inside! This is indicative of very high voltage spikes! The battery kept drying out indicating something was up.... Testing with an oscilloscope showed spikes up past 36V, and even negative voltages! Root cause could be any number of things, including poor/corroded/intermittent electrical connections and switches.

I managed to "fix" it with a very clever use of Zener diodes to "clip" any voltage spikes. Linear regulators could also be used, but the voltage needs to be set around 7.2V so that the lead-acid battery gets a proper charge, or it will slowly die from sulphate.

To fix your bike we'd need an accurate wiring diagram for your bike in its original and current state.