Scoot F.A.Q.

Q. Why are my headlights dim and how can I improve them?

The two most common issues are a lack or power to your headlight(s) or low wattage bulbs installed. To determine if your headlights are receiving enough power to illuminate at full intensity, first determine if your headlights are AC or DC operated. If your headlight(s) will light without the engine running, they are powered by the battery's DC power. If your headlight(s) will come on only when the engine is running they are supplied with AC power from the stator.

DC operated headlights will be dim if the battery has a low charge or is not functioning properly. Check your battery and replace it if necessary. Also make sure your battery is the correct one for your scooter, at least the specified size according to the owner's manual. If the battery appears to be in good condition, check battery charging with the engine running. If your scooter doesn't appear to be providing charging voltage check the stator's output. Most scooters should put out 50VAC or more on the wires for charging or lighting, but refer to a service manual for additional checks and specs. If the stator checks out, you may have a problem with the voltage regulator/rectifier.

AC operated headlights tend to be dim at idle or low engine speeds, but should reach full brightness as RPM increases. Dim headlights at idle may be improved by setting idle speed higher, but avoid setting the idle so high that the scooter tries to move without applying additional throttle or that the tire spins fast while on the center stand. If your headlights are always dim check the stator's output, looking for at least 50VAC when revved for most scooters.

Either AC or DC powered lights may be dim if there is a poor connection somewhere in the system. Check connections at the stator, regulator/rectifier, battery, headlight on/off switch, high/low beam switch, and at the headlight itself. Also verify that you have good engine, frame, and battery grounds.

If you have plenty of power to the headlight(s), usually 12V+ AC or DC, then your problem may be low watt headlight bulbs. Some scooters come equipped with as little as 18W incandescent headlight bulbs in stock form. For comparison, most cars or motorcycles use around 55W (each) bulbs in their headlights. There are higher wattage versions of many typical scooter headlights available. Scooters typically support around 50-70W total for headlight power, but bright high output bulbs generally burn hotter and can cause the headlight housing, connectors, or even parts near the headlight to melt. Most report good results switching from a single 18-35W bulb up to a 45W replacement. Scooters with two headlights on at once will probably need to limit each light to 35W. Some scooters with higher output charging systems may be able to power higher rated lights, but still may suffer from heat issues with bright lights. Regularly check your headlight housing and wiring condition for a while after installing brighter lights.

Common Scooter Headlight Bulb Styles
P15D / "Bullet"
BA20D / "B35"

Related Info :
Scooter Battery Checks
Charging System Check
Easy Stator Charging/Lighting Output Check
BA20D Headlight Comparisons
BA20D to H4 Bulb Conversion
Dual Headlight Modification

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