Before you replace the battery , up grade the crappy original rectifier ~ this is very important .

The front brakes have a  brake light switch too , when the battery is old , even the brake lamp's current draw will kill it .

The flip side is when you putter off down the road , the alternator will ' spike ' and blow the $45.00 headlamp and the speedo bulbs etc. too .

I'm now using a 6 V # 1154 taillamp and it's great ! super bright and no stalling , the headlight and speedo lamps are all brighter too .