Diagnose and Repair Motorcycle (Scooter) Not Charging Battery | Stator Coil | SYM Jet Power 125

Today, I want to show you how to diagnose and repair scooter SYM Jet Power 125 hard to crank/start due to a faulty alternator/stator coil. Here are some common symptoms of the faulty spark plug or bad spark plug, e.g., hard to start, engine run sluggish, no spark produced by the spark plug, the engine does not crank smoothly, etc.

References:

1. SYM Jet 4 125 Manual
   
   

Step 1: Diagnosis motorcycle

1. My battery is not charging even when I start the motorcycle and can cause a low voltage/dead battery.
2. You can see the battery voltage at 12.20 V and not increasing.
   
   
   
3. After the diagnosis of my motorcycle, I found that my charging system had failed. 4 common places that need to be troubleshot are the alternator, regulator, fuse, and wiring/connector.
   
4. Remove the 3 pin connector of the alternator.
   
   
   
   
   
5. Measure the resistance between the white wire on the alternator and the frame ground or green wire. If the resistance exceeds the standard, then change the alternator/stator coil.
   
   
   
   
   
6. Next, measure the resistance between the yellow wire on the alternator and the frame ground or green wire. If the resistance exceeds the standard, then change the alternator/stator coil. (refer to above picture).
   
   
7. In my case, both charging and lighting coil are below than standard value.  So, replace the alternator or stator coil.

Step 2: Removal of stator coil/alternator

1. Disassemble the body cover in sequence 1 → 2 → 3 as shown in the figure below. You can watch my previous video or post on how to remove body cover step by step.
   
   
   
   
   
2. Remove the fan cover (4 bolts).
   
   
   
   
   
   
   
   
3. Remove the cooling fan (4 bolts).
   
   
   
   
   
4. Remove a nut on the flywheel using special tools (pulley holder spanner) to hold the flywheel from turning.
   
   

   
   
   

   

   
   

   
   
   
5. Remove the flywheel with the flywheel puller.
   
   

   

   
   
6. Remove the 6 bolts for the pulse generator, stator coil, and cable guide.
   
   
   
   
   
7. Remove the connectors of the stator coil and pulse generator connector.
   
   

   

   
   

   

   
   
8. Untie the wiring, and remove the stator coil.
   
   

   

   
   
9. I buy this cheap OEM stator coil for SYM Jet Power 125.
   
   

Step 2: Installation

1. Install the spark plug in reverse order of removal.
   
   
2. Start and take the reading with a multimeter. You can see from the picture below the reading around 13 V ++ compared to before replacing the alternator.
   
   
   
   
   

The link tools and components replacement I used in this video are listed below:

Tools/Components/Items (Shopee):

1. Spanner Set
2. Screwdriver Set
3. Flywheel Puller
4. Puller Holder Spanner
5. SYM Stator Coil/Alternator

Tools/Components/Items (Lazada):

1. Spanner Set
2. Screwdriver Set
3. Flywheel Puller
4. Puller Holder Spanner
5. SYM Stator Coil/Alternator

Tools/Components/Items (Aliexpress):

1. Spanner Set
2. Screwdriver Set
3. Flywheel Puller
4. Puller Holder Spanner

Video:

That all from me. If you have any suggestions, please write in the comment section. Thank you for your time 👷.