With the latest V.2 Cylinder kit series from NARAKU, we can offer a more advanced product. The bore has been taken out to 52.4mm. The external diameter of the cylinder base has not been affected by the increase in displacement. This means alterations to the crank cases are generally not required. As a 4 stroke cylinder is effectively just a hole, the emphasis on technological development was placed on the piston and compression. The piston has 2 additional CNC-machined oil grooves in the piston skirt, which collects engine oil to lubricate the cylinder bore and improve characteristics in extreme circumstances. The molybdenum coating aids the crucial running-in period. 2 oil recesses and a groove at each bearing point ensure the gudgeon pin is adequately lubricated. The compression ratio and power delivery set this cylinder apart. The kit contains a cylinder head with larger valves and optimized inlet and outlet ports. For technical reasons, a bore size of 50mm or larger requires a larger head for on-going use. This kit is currently one of the biggest conversions on the market. The kit can use the original carburetor, but we recommend changing the main jet.
This is the absolute biggest big bore kit that can be fitted on the 139QMB engine. These are often called 110cc kits by the chinese sellers.
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