Honda CG125 Style 156FMI 125cc to 150cc 62mm Big-Bore Kit
Aftermarket big-bore cylinder and piston kit for selected Honda CG125-style Chinese 125cc OHV / pushrod engines using the 156FMI / 1P56FMI engine platform. This kit increases the bore to 62 mm and, with the common 49.5 mm stroke, gives approximately 149cc.
Technical Specification
- Application type: Honda CG125-style Chinese 156FMI OHV / pushrod engine
- Engine family: 156FMI / 1P56FMI
- Cooling: Air cooled
- Bore: 62.00 mm
- Typical compatible stroke: 49.50 mm
- Approximate capacity after conversion: 149.4cc
- Piston / gudgeon pin diameter: 15 mm
- Typical cylinder height: approximately 68 mm
- Approximate cylinder sleeve / spigot diameter requiring crankcase clearance: 68 mm
- Condition: Brand new aftermarket big-bore conversion kit
Important Crankcase Machining Requirement
The engine casing / crankcase will need to be bored out to accommodate the larger cylinder sleeve. The 62 mm big-bore cylinder uses a larger lower sleeve / spigot than the standard 125cc barrel, so the crankcase mouth must be machined to provide sufficient clearance before the cylinder can be installed correctly.
This is not normally a simple bolt-on conversion. The crankcases should be stripped and professionally machined so the sleeve fits concentrically without excessive clearance or interference.
Common Aftermarket Reference
- M587-A095 – common aftermarket reference for this 62 mm / 15 mm CG-style big-bore kit
Typical Kit Contents
- 62 mm cylinder / barrel
- 62 mm piston
- Piston ring set
- 15 mm piston / wrist pin
- 2 x piston-pin circlips
- Cylinder base gasket
- Cylinder-head gasket
- Valve-stem seals on many kits of this specification
Use the product photographs as the final guide to the exact components supplied.
Compatibility
- Selected Chinese 156FMI / 1P56FMI 125cc engines
- Honda CG125-style OHV / pushrod engine designs
- Chinese CG / GY 125cc motorcycles using a 15 mm piston pin
- 125cc-to-150cc big-bore conversions where the engine casing is machined for the larger sleeve
- Selected motorcycle / ATV applications using the same CG-style engine architecture
Important Honda CG125 Fitment Note
This product is intended for Honda CG125-style Chinese engines. It is commonly described in the aftermarket as a Honda CG125 / CG150-style big-bore kit, but it should not be assumed to be a direct bolt-on replacement for every genuine Honda-manufactured CG125 engine.
Before ordering, confirm the engine is the correct 156FMI-style OHV / pushrod design, uses a 15 mm piston pin and has a compatible stud pattern, cylinder head and oil-way arrangement.
Critical Fitment Checks
- Confirm the engine is a CG-style OHV / pushrod design.
- Confirm a 15 mm piston pin is used.
- Confirm cylinder stud spacing and oil-way position.
- Compare the cylinder head and gasket pattern.
- Confirm the crankcase can be safely machined to accept the approximately 68 mm sleeve / spigot.
- Do not fit to incompatible OHC engines or dual-port cylinder-head designs.
Installation
Professional engine machining and assembly are strongly recommended. The crankcases must be bored accurately for the larger cylinder sleeve before installation. Check piston-to-cylinder clearance, ring end gap, piston orientation, gasket alignment, valve clearance and oil passages during assembly.
After assembly, rotate the engine by hand before starting and use an appropriate running-in procedure. Carburettor jetting / fuelling may also require adjustment to suit the increased engine capacity.
Shipping Information
- Packed shipping weight: approximately 2.2 kg
- Estimated packed dimensions: 22 x 22 x 17 cm