Nothing is more frustrating for motorcycle owners than encountering power supply issues. Whether you're an experienced rider or a beginner, a motorcycle with no power can ruin your day and leave you stranded. In this blog, we will walk you through a real-life scenario of diagnosing and fixing a motorcycle power problem step by step.
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| SYM 125 Jet Power Scooter |
Step 1: Verify Battery and Fuse Condition
- The first thing to check when facing power issues is the battery and fuse. Ensure that both the battery and the fuse have a voltage reading between 12V and 13Vdc. A low or dead battery could be the root cause of the problem.
Check battery 
Check fuse
Step 2: Inspect the Main Switch Terminal
- If the battery and fuse are in good condition, move on to the main switch terminal. Make sure the main switch has a supply voltage between 12V and 13Vdc, and the ground or body wire registers a voltage of 0Vdc.
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| Check main switch terminal |
Step 2: Check Power Supply Connector for Main Switch
- If there is low voltage at the main switch terminal, examine the voltage at the power supply connector for the main switch. Look for signs of corrosion or damage on the connector pins.
Inspect the connector 
Measure voltage of the connector
Step 3: Clean Corroded Pins
- If corrosion is found on any terminal pin, clean it thoroughly using sandpaper. After cleaning, reconnect the pin to the connector. Corrosion can disrupt the flow of electricity and cause voltage drops.
Clean the corrosion terminal using sandpaper 
Reconnect the connector
Step 3: Verify Main Switch Supply Voltage
- After cleaning the corroded pin, recheck the supply voltage of the main switch to ensure it ranges between 12V and 13Vdc when the switch is both ON and OFF.
When the switch is OFF, the voltage normal 12V 
When the switch is ON, the voltage drop to 8V
Step 3: Inspect the Starter Magnetic Switch
- If the voltage is fine when the switch is OFF but drops when it's ON, the starter magnetic switch may be causing the issue. Open it up and inspect its condition.
Check starter magnetic switch
Step 3: Identify the Problem
- In this scenario, all components were working fine except for low voltage at the connector. The suspicion is that there may be corrosion at the connection point between the battery and the connector.
Starting circuit 
Suspected corrosion at the jointing area
Step 3: Temporary Fix with a Jumper Wire
- To confirm the issue, a temporary fix was applied by connecting a jumper wire from the battery's positive terminal to the connector. This bypassed any corroded connection.
Temporary jumper the wire
Step 3: Recheck Main Switch Supply Voltage
- After applying the temporary fix, recheck the supply voltage of the main switch to see if the voltage drop has been resolved.
Measure the voltage of the main switch
Step 3: Start the Motorcycle
- With the voltage issue resolved, attempt to start the motorcycle to see if it's working correctly now.
Start the motorcycle
Step 3: Install a New Wire
- Since the temporary fix confirmed the issue, it's time to install a new wire from the battery to the connector using a 2.5mm² wire size. Crimp connectors were used for secure connections.
Crimp the connectors 
Rewiring a wire 
Secure the connection
Step 3: Test the Motorcycle Again
- After installing the new wire, start the motorcycle again to ensure that the power issue has been completely resolved.
Motorcycle working normally again
The link tools and components replacement I used in this video is listed below:
Lazada:
Aliexpress:
Video:
Diagnosing and fixing power supply issues in a motorcycle can be a challenging but rewarding experience. By following a systematic approach and inspecting each component carefully, you can identify and resolve the problem effectively. If you find this guide helpful, don't forget to share it with your fellow riders and friends. Safe riding!