IMO trying to use that white wire is a poor choice. For one thing it robs powers from an ignition system that's marginal at best. If you don't understand the limitation it's very difficult to get it to work at all. With a diode to limit draw from the half of the cycle the engine don't use it's possible to get some small amount of power. Not worth the trouble though.
A 50-100 LED bicycle light using rechargeable AA cells runs for many hours and lights up the road like a searchlight. Cheap, reliable, light, and bright, I keep one in my pack to clip on for those rare occasions when I get stuck out in the dark. Even a small 9 LED flashlight will suffice. Or any old mini-maglite bulb type in a pinch.
Originally Posted by westonforbes
I am trying to install a headlight i made on my 49cc bike, I am having some issues though and i need some help from anyone. First off, what I have built. I went to my local superstore and bought a handheld spotlight for like 7 bucks, I also bought some aftermarket car headlights. I took apart the spotlight and salvaged the 6v bulb and the 6v rechargable battery. I then removed the 12v bulb from the headlight and installed the 6v (exact same bulb but different voltage). I now have everything mounted with a containing box and I can run the light if i wire it directly to the battery but I cannot get it to run from the engine whitewire. I have tried many combinations, connecting directly to the engine and combinations involving the battery. I have a fairly good understanding of electrical basics but it just wont seem to work. I worry that the bulb may be too many watts and is not leaving enough for the sparkplug. If anyone has done a similar project I would love to hear about it! or any ideas on how to accomplish this. If i can get this working I will post a full lighting tutorial with pics and what to buy, cause so far this is a DIRT CHEAP lighting solution and it would help alot of people. Thanks in advance.