Here is a product installation manual in English:

Installation Manual for 50mm Piston Pin Set for 100cc Motorized Bicycle Engine Kits

Tools Required:

• Socket wrench or ratchet and socket
• Torque wrench
• Pliers
• Screwdriver (flathead and Phillips)
• Wrench (adjustable and fixed)
• Lubricant (recommended)

Installation Instructions:

1. Preparation:

• Ensure the engine is cool and free from any debris or old lubricants.
• Familiarize yourself with the engine's internal components and the new piston pin set.

2. Removing Old Piston Pin:

• Use a socket wrench or ratchet and socket to remove the old piston pin from the engine block.
• Be careful not to damage the surrounding components.

3. Inspecting New Piston Pin:

• Inspect the new piston pin for any defects or damage.
• Ensure the pin is free from debris and lubricants.

4. Installing New Piston Pin:

• Apply a few drops of lubricant to the new piston pin.
• Carefully insert the new piston pin into the engine block, ensuring it is properly seated.

5. Tightening Piston Pin:

• Use a torque wrench to tighten the piston pin to the recommended specification (usually around 20-25 ft-lbs).
• Be careful not to overtighten, which can damage the engine block or piston.

6. Reassembling Engine:

• Reinstall any removed components, such as the cylinder head, crankshaft, and other parts.
• Ensure all components are properly tightened and secured.

7. Final Check:

• Check the engine for any signs of leaks or damage.
• Ensure all components are properly lubricated and functioning smoothly.

Important Notes:

• Always refer to the engine manufacturer's manual for specific instructions and recommendations.
• Use caution when working with high-pressure and high-temperature components.
• Wear protective gear, such as gloves and safety glasses, when working with tools and engine components.

By following these instructions and using the required tools, you should be able to successfully install the 50mm piston pin set for your 100cc motorized bicycle engine kit.