C70 70cc Cylinder Assy

C70 Cylinder Assembly

🏭 Cylinder Assembly · Piston Kit · Engine Rebuild Kit

For Moped, Cub, Dirty Bike & ATV · Fits 139FMB, 147FMD, 147FMF, 150FMG engines

This is the C70 Cylinder Assembly, a core component of the engine's combustion chamber. It is suitable for Mopeds, Cub series, Dirty Bikes, and ATVs, and fits engines including 139FMB, 147FMD, 147FMF, 150FMG, and similar models.

This cylinder assembly includes a complete set of cylinder, piston, piston rings, and piston pin, making it an ideal choice for engine rebuilds or performance restoration. The cylinder is manufactured from high-quality cast iron or aluminum alloy (depending on model) with a precision-honed inner surface for excellent wear resistance and sealing. The piston is made from high-silicon aluminum alloy with strict heat treatment and dimensional control. The piston ring set provides superior sealing and oil control. This assembly is the perfect replacement solution when the original cylinder shows signs of scoring, excessive wear, stuck piston rings, or low compression.

This cylinder assembly fits the following engine models:

• Mopeds - Various 50cc-150cc moped models (underbones, scooters, etc.)
• Cub Series - Honda Cub and clone models
• Dirty Bikes - Small off-road motorcycles
• ATVs - Small-engine quad bikes / kids ATVs
• Other vehicles using 139FMB, 147FMD, 147FMF, 150FMG engines

• Power Loss: Cylinder wear leads to poor sealing, reduced compression pressure, and noticeable power decrease.
• Oil Burning: Blue smoke from exhaust, increased oil consumption, heavy carbon buildup on spark plug.
• Hard Starting: Low compression makes starting difficult, especially when cold.
• Knocking Noise: Excessive piston-to-cylinder clearance causes metallic knocking during operation.
• Increased Fuel Consumption: Reduced combustion efficiency leads to significantly higher fuel consumption.
• Low Cylinder Compression: Compression test results below standard specification.

If you experience these symptoms, inspect the cylinder assembly and piston components, and replace if necessary.

• OEM Specifications: Manufactured to original dimensions and tolerances for perfect fitment.
• Precision Honed Cylinder: Cylinder bore is precision-honed with a cross-hatch pattern for optimal oil retention and ring break-in.
• High-Quality Piston: Made from high-silicon aluminum alloy with low thermal expansion and excellent wear resistance.
• Complete Piston Ring Set: Includes compression rings and oil rings for superior sealing and oil control.
• Precision Piston Pin: Surface-hardened with precise fit to piston pin bore for smooth operation.
• Complete Assembly: Includes all core components needed for installation; no need to purchase additional parts.

🔧 Installation Tip

1. Replacing the cylinder assembly requires removing the engine and cylinder head; professional installation is recommended.
2. Clean cylinder and crankcase mating surfaces thoroughly and replace with a new cylinder gasket.
3. When installing piston rings, ensure proper ring gap orientation with gaps staggered according to specifications.
4. Apply engine oil to piston and cylinder bore for pre-lubrication; use a piston ring compressor when installing the piston.
5. Ensure piston pin circlips are fully seated in grooves to prevent axial movement.
6. Tighten cylinder head bolts in a crisscross pattern to the specified torque.
7. After installation, add appropriate engine oil and manually rotate the crankshaft several times to check for binding.
8. New cylinder assembly requires a break-in period; avoid high RPM and heavy loads during initial operation.

⚠️ Important Notice: This is a C70 cylinder assembly (including cylinder, piston, piston rings, and piston pin) suitable for Mopeds, Cubs, Dirty Bikes, ATVs, and vehicles using 139FMB, 147FMD, 147FMF, 150FMG engines.
Specification Selection: For 70cc/90cc engines, select the 47mm piston diameter version. For 110cc engines, select the 52.4mm piston diameter version. Please verify your engine displacement and original specifications before purchase.
Ensure proper piston ring orientation and tighten cylinder head bolts to the specified torque. Images are for reference only. The actual product may vary.