Why My Pocket bike doesn’t start: Problem and solutions

Last Updated on July 16, 2022 by Nafi

There can be many reasons behind a pocket bike doesn’t start. Most of the cases that we have found so far were because of the ignition system and spark plug fault. A faulty spark plug is responsible for the failure of engine startup. However, issues can persist in fuel supply and alternator that play the role to run the engine.

The failure to start a pocket bike is cumbersome and the rider has to suffer a lot. It’s irritating to try again because the pocket bike offers a pull start most of the time. So so pulling the rope with no result, again and again, makes a rider lose interest to keep doing the same. If you have a pocket bike you should know everything about this before you are able to handle this in case any trouble appears. So let’s see what are the point of reason that can the cause of start failure.

The reason for pocket bike startup failure include

  • Dirty Spark plug
  • Spark plug loose connection with spark cap
  • No power on the spark plug
  • Inadequate fuel supply
  • Carburetor blockage
  • Fault in the Ignition system
  • Fault in Alternator.

Dirty Spark plug

A dirt spark plug can’t produce enough spark flame. Spark plug plays the biggest role in starting the engine. The spark plug carries the spark on its top end. When the piston in the engine cylinder compresses the fuel and air, the spark plug throws a spark fire. The fire burns the oil and exhausts the smoke. This is how the engine generates the power that pushes the piston down and repeats the engine cycle.

So if the two lids i.e negative and positive lid got a barrier of dirt they lost continuity. So you can open the spark plug by rotating it anticlockwise. Check whether the lids are in good condition or burnt. If they are burnt, you have to replace the spark plug with a new one. If you find dirt or black ash there, you can just clean it and this should possibly work.

If there is no power through the spark plug, then you won’t see any spark on the spark plug. Before you plug it in the engine check it by pull-start the engine. When you pull the starter rope, you can see spark flam on the plug lid. The ambient light should be dim like in the evening to see the spark flame.

Check if the spark plug cap is properly connected to the spark plug. An open wire or lose connection will probably cause high resistance in the line and will not let the current pass to the spark plug.

If you want to know how to start a pocket bike with out key, see this post.

Improper fuel Supply

Your pocket bike starts by starting its engine and continuing its running cycle. If the engine can’t continue its cycle may be due to low fuel there will be no effective combustion. So the piston will stop moving. An inadequate fuel supply can cause this. Even it’s as common as it doesn’t need to be a science that an engine can’t run without fuel. Check if there is enough fuel in the fuel tank. Check if the fuel switch is throttled. If you find no issue with these two points, you might need to check the carburetor.

Blockage in the fuel or air filter might be the reason behind the low fuel supply. If you find the filter dusty or blocked, clean it with a dry brush.

Sometimes, sediments of oil are found at the bottom of the fuel tank. If you see something like this, you should consider cleaning your fuel tank. Release the oil from the rubber pipe under the fuel tank. Take it in a bottle. You can then clean the fuel tank. You should also be careful about the quality of oil you are using on your bike.

No power on Spark Plug

Missing of current in the spark plug can be caused by several reasons throughout the electrical line. There are two devices in the path. The alternator and the ignition unit, that’s recently a CDI unit.

An alternator consists of a Stator and a rotor. The stator consists of several copper-coil cores that store inductive current for a short time. Overload to the stator coil might cause this to break or shorten to other wires. The rotor might be jammed by burnt grease and dust.

The CDI unit is the latest Ignition device in which the alternator charges the capacitor in the CID unit. Then the current in the CDI unit powers up the spark plug. In the CDI unit, the electric voltage from the alternator is stepped up to 40 thousand volts. This requires coils inside the CDI unit. If the coil is burnt or shortened, the power supply to the spark plug will not be possible.

You can check a CDI unit with a multimeter. Set the multimeter to Resistance mode. Connect the two probes of the multimeter to the two terminals of CDI. Those terminals are opposite to the spark plug cable. If your meter shows some Ohm to kilo Ohms, then the coil is good. A burnt coil will show Mega Ohm. A shortened coil will show 0 to 20 Ohm in the resistance meter.

Can a pocket bike not start due to a pull starter issue?

It’s very unlikely that your pocket bike pull starter falls into difficulties. However, anything can happen more or less frequently. A broken gear might be detached from the gear group that might cause start failure. But as long as you replace the engine oil regularly, the internal gear shouldn’t decay or produce higher heat.

Can I do this troubleshooting myself?

Do it by yourself need prior knowledge about what you doing. Things should be done after you understand how these things work. You should know the principles of how a pocket bike works or simply how a motorcycle works. You should also know the basic electric principles to handle electric wires and devices to check if they are in good condition.

This instruction is just as a reference. If you have no prior knowledge, it’s not at all safe for your to attempt to troubleshoot a failure of start by yourself.

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