Diagnose and Repair Motorcycle (Scooter) Hard to Start | Replace Spark Plug | 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 spark plug. 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: Removal of Battery

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 spark plug cap.
   
   
   
   
   
3. Use spark plug spanner and rotate anti-clockwise to remove the spark plug.
   
   
   
   
   
4. Test the spark plug by reconnecting the spark plug cap, then position the plug to the engine body. 
   • Replace the spark plug if the spark produced is weak.
   • The bad spark plug on the right side is a bad or burnt spark plug that needs replacement.
   • Measure the spark plug gap if the gap is less than 0.6 mm, then replace the spark plug.
   
   

   

    

Step 2: Installation

1. Install the spark plug in reverse order of removal.
   
   

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. Tube Bar Spark Plug Spanner
4. Spark Plug (C7HSA)

Tools/Components/Items (Lazada):

1. Spanner Set
2. Screwdriver Set
3. Tube Bar Spark Plug Spanner
4. Spark Plug (C7HSA)

Tools/Components/Items (Aliexpress):

1. Spanner Set
2. Screwdriver Set
3. Tube Bar Spark Plug Spanner
4. Spark Plug (C7HSA)

Video:

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