I have a Halfords 200% brighter headlight bulb. It is better than standard but I wouldn't say it's twice as bright. It is said they fail quicker but I've had it in for 4 years now. I live in a rural area so riding on unlit roads it does make a difference.
In terms of being seen the best thing I've found is a light that wobbles slightly. It creates the same effect as a flicker and that certainly catches motorists' attention.
The next best thing is to create a triangle of lights. I have two small leds mounted on the forks. They are wired into the dipped beam circuit.
1. Make sure the new battery is fully charged. Just because it's new doesn't mean it's fully charged.
2. Replace the spark plug. A dirty plug won't fire.
3. If it's sat for three years with fuel in the carb you can bet there's gummed up fuel residue in there. Give it a good clean.
Mississippi Bullfrog's post in Spotlights on a Yamaha YBR 125 55 reg was marked as the answer