This kit is compatible with the following Honda models and frame number ranges:
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Monkey / Gorilla: Z50J-1000001～1323946 and Z50J-1323947～1510400
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Dax 50 (6V): ST50-1000001～6299999 and ST50-6300022～6346265
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Chaly 50: CF50-1000001～2899999
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CD50: CD50-1100001～1330600
This premium 88cc STD-Type2 Big Bore Kit from Kitaco is engineered for Honda Monkey, Gorilla, and the compatible models listed above. It delivers strong, usable power and torque improvements throughout the RPM range while remaining well-suited for everyday street riding.
Kit Contents & Performance Features
The kit includes a high-durability cylinder head featuring an optimized combustion chamber, improved port shapes, larger valves, a high-lift camshaft, and a high-compression cast piston. These components work together to enhance airflow and combustion efficiency, resulting in noticeably better low- to mid-range torque and improved top-end performance compared to the stock setup.
Key specifications:
- Displacement: 88cc
- Bore: φ52mm
- Stroke: 41.4mm (retains the stock crankshaft)
- Pre-assembled valves in the cylinder head
- High-compression piston matched to the combustion chamber
The Key Difference: All-Aluminum Hard Chrome Cylinder
This specific version features Kitaco’s premium all-aluminum hard chrome cylinder. It differs from the standard version of the kit, which uses an aluminum cylinder block with a traditional cast iron sleeve.
Benefits of the Hard Chrome Cylinder:
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Superior durability and wear resistance: The hard chrome plating is applied directly to the aluminum bore, creating an extremely tough, low-friction surface. This significantly reduces wear from the piston rings compared to a conventional cast iron sleeve, helping the engine maintain performance longer and extending overall engine life.
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Improved heat dissipation: The full aluminum construction (without a heavy iron sleeve) allows heat to transfer away from the combustion chamber more efficiently. This helps keep the engine running cooler — especially beneficial for air-cooled bikes during extended rides or in warmer conditions.
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Reduced weight: Removing the iron sleeve lightens the cylinder assembly slightly, contributing to a better power-to-weight ratio and sharper engine response.
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Smoother operation: The hard chrome surface offers excellent low-friction properties, promoting smoother piston movement, reduced internal drag, and improved sealing over time.
In summary, choosing the hard chrome cylinder version gives you a higher-end, more durable upgrade that runs cooler and lasts longer, making it ideal for riders who want reliable performance from their big bore conversion.
This kit is a great choice for enthusiasts seeking a meaningful power increase without sacrificing street usability. For best results, we recommend using high-quality engine oil, correct carburetor jetting, and following proper break-in procedures. Professional installation is advised, and always verify compatibility with your specific model and year.
