NCY 171cc Big Bore Kit - 61mm | No Case-Cut for GY6 QMB139 This kit includes all the

This kit includes all the parts that commonly fail in a stock Chinese clutch

139QMB-based 50cc / 80cc engines with the following engine codes:

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Grooves: Multiple angled liner grooves for debris channeling

NCY 171cc Big Bore Kit - 61mm | No Case-Cut for GY6 QMB139 This kit includes all theNCY 171cc Big Bore Kit (61mm) No Case Cut for GY6 150 The NCY 61mm Cylinder Kit is the only 171cc upgrade available in the U. S., designed to fit without machining your engine cases. Featuring a specialized 62. 9mm outer skirt, this aluminum cylinder drops directly into standard GY6 150cc blocks. It is the ultimate "weekend project" for riders demanding a massive jump in torque and acceleration without the need for professional machine shop services.