How to start a pocket bike without a key?

Last Updated on July 16, 2022 by Nafi

To start a Pocket bike without a key you should understand the mechanism behind how a key permits a pocket bike to start. Then the electric diagram of a bike comes into action. Shortly, you have to do the job of the key by your hand to start a pocket bike.

How the key prepares a pocket bike to get started?

A pocket bike mostly similar to other bikes has an engine that is run by oil or gas. To burn the gas it needs fire. The electric parts of the bike do the job of firing the fuel of the bike inside an engine that generates power. So the electric current causes a short circuit at the spark plug inside the engine with no direct touch of negative and positive terminals. Normally spark can be occurred only by physical touch. But in the case of high voltage, the current starts to travel from negative to positive with a closer contact like 1cm or less. This is the nature of high voltage alternative current to pulsate and travel to an opposite current bearer lid and cause a spark fire.

Spark fire on 1 KV

Figure 2 Spark fire on 1 KV

Spark fire of 40KV

Figure 3 Spark fire of 40KV

While the pocket bike is keyed off, the power connection to this spark plug is cut and so fire is there in the engine to burn the fuel. So when you try to pull start the oil comes to the engine but without fire, it can’t produce any explosion and this cycle doesn’t start to keep the engine running.

To start the pocket bike without the key, you have to connect power to the spark plug manually. Before you do that it’s good to get to know the electric diagram of a pocket bike.

The pocket bike has a similar electric diagram like some other common motorcycles. Capacitor charging ignition that is CDI is deployed in the modern pocket bikes. So a CID unit is installed between the magnetic power generator and spark plug.

Schematic of CDI unit

Figure 1. Schematic of CDI unit

An ignition coil is a component that steps up the voltage to a higher voltage which is as much as 50KV. While you will be opening the bike seat or other covering to find the electric unit, you have to keep in mind the electrical diagram shown in Figure 1. So follow the diagram to find out where actually the disconnection occurred. You can also find this by following the way to the lock.

Components for further experiment

  1. Excitor Coil
  2. Diode
  3. Trigger
  4. Pulse Rotator
  5. Capacitor
  6. Resistor
  7. Thyristor (SCR)
  8. Ignition Coil
  9. Spark Plug

What if the power is cut between the Excitorcharging coil and Diode?

Note: When a wire is cut or a switch disconnects the line, the circuit becomes an open circuit.

 If any of the connecting wire is found cut and taken to lock switch, rewire them with high-quality copper cable. Before you handle these connections, make sure you disconnected the battery line. A high voltage can be ready on the output of the ignition coil. So, if you are exposed to high voltage, it’s less like to forgive you.

For better understanding let’s call the bike’s key-lock as an electric switch. So this switch connects and disconnects the power to the engine’s spark plug. The switch can be at several points of the circuit shown in the photo Figure 1.

But a switch is never set at the output of the ignition coil which is a high volt current supplier cord.

Since in CDI system ignition coil is charged discharging the capacitor, the lock switch can be set in here too. The way is the same to rewire and close the circuit.

Before you connect the battery or pull start the pocket bike, you can use a multimeter to check if there is any direct short circuit in the circuit, maybe accidentally caused by you. If everything is fine you can connect the battery and pull start the pocket bike. The bike has no other way than to start.

What if it’s an electric bike?

The electric bike is much easier to start without a key. The electric bike has fewer electric components because it’s not run by an engine. The electric bike comes with a battery and electric motor. The motor is of a higher RPM-rated motor that also has speed control capability. 

A potentiometer is used at the bike’s hand to control speed. Bikes speed is changed by changing its motor speed. Motor speed can be changed by increasing and decreasing the voltage supplied to it. The highest-rated voltage ensures the highest speed of these pocket bikes, while a rated lowest voltage indicates the motor’s lowest speed.

The maximum and minimum voltage that can be fed to the motor is specified on the motor’s documentation. The rotation speed on different voltages is also specified in the same literature at RPM.

In the case of an electric bike, the lock switch can be either between the battery and the Potentiometer or between the motor and the Potentiometer. The electric pocket bike doesn’t operate with high voltage, so it’s safe for you to handle the electric line. But you should always use hand gloves to handle the electricity. Because a small spark fire can cause burn at your fingertips.

Note: If the Speed controller meter on the bike’s hand is physically locked and you find it can’t be rotated, then you can’t run the pocket bike without cutting the lock.

A pocket bike comes with a simple diagram of components altogether. So if you observe them for some time, you will easily understand. In 90% of cases, you can start your pocket bike by manual surgery. But these are not recommended by the manufacturers and often be a cause of warranty void. So don’t do this if it’s not that urgent.

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