Scooter headlight stopped working and bike idling high and sluggish under power

not enough exhaust flow will cause it to be sluggish -- open the exhaust up so it breathes.

Check if the charging system works ok.
At idle with lights off, you should see 13.5-14.5V on battery's terminals and 0.5V less with high beams on, at idle speed as well as at 4000rpm.
Use a fresh good verified battery to take the readings.

People this is a scooter. The problem is that your idle screw on the Carb needs adjustment. The idle screw can be adjusted with a Philips screw driver. Follow your throttle cable to the carb. You'll see a screw that pushes a pulley down raising your rpms. This will lower your idle causing the rpms to drop and since your scooter transmission is propelled my higher RPMs the bike will stop thrusting you forward when you stop at red lights.

Check the charger voltage. It should be 29 volts when not connected to the scooter. Anything less is a component gone bad on the circuit board.

The choke has nothing to do with the Idle. If the choke cable is too loose, there's a nut on the backside of the bracket where the knob is. You can tighten it just a bit but be careful, the parts are made of plastic and they break easily.

On your idle, if your bike is equipped with a carb, remove the air filter cover. At the top right of the carb is the throttle stop screw. Clockwise to increase the speed, Counterclockwise to decrease.

If your bike fuel injected, you'll have to take it to a shop to get the idle set, It's done electronically.

Good Luck
Steve

may need a new battery it may not be strong enough at idle

sounds like you have too much voltage coming out from your battery, mabey a faulty regulator. The easiest way to test this, is to get a multi - meter, and check the volage output at the battery, with the engine running, at idle should read about 12.5 - 13 volts. Then rev the bike up, and seeif the reading changes, it should not go more than 13.8 or 14 volts max. If it does, then i say you have a faulty regulator/ rectifier.

The best way is to twist the high speed screw in all the way (do NOT jamb it in - gently screw until it wants to stop), then back it out 1.75 revolutions. Start the motor, and run it under load. Stop, lean it out some by screwing in the mixture screw in 1/4 turn. Try it. If it gets better, repeat until it gets worse and then go back one step. That should be the setting. The same if you chose to richen the mixture by turning the mixture screw OUT 1/4 turn. Repeat and follow the above directions. Going one way or the other is a guess at first, and you hone in for the best performance. For the idle screw, just piddle with it until it sounds good at idle. You should start out at 1.5 turns from closed.

Cutting the wire will do. My Mio also have a HID any that's what we did (cutting one wire). But you can also try alternative like installing a fast charger. So you can charge up your battery fast as you use your HID.

No problems encountered with my HID using the cutting methode.