100cc Naraku Racing Big Bore 52mm Cylinder Kit for 50cc 4-Stroke 139QMB Scooters INCLUDES: Cylinder Bore: 52.4mm Cylinder Sleeve Outer Diameter: 54.4mm Wrist Pin Diameter: 13mm Total Piston Height: 36.3mm Compression Height (from center of wrist pin hole to top edge of piston): 20mm Non-emissions style head Intake Valve: 23mm Exhaust Valve: 20mm Intake Port Diameter: 20.8mm Exhaust Port Diameter: 18.7mm Uses Short 64mm Valve Stems COMPATIBILITY: Amigo – 50cc 4-Stroke Scooters Apollo – 50cc 4-Stroke Scooters Baotian – 50cc 4-Stroke Scooters Baron – 50cc 4-Stroke Scooters Bintelli – 50cc 4-Stroke Scooters BMS – 50cc 4-Stroke Scooters Coolster – 50cc 4-Stroke Scooters CSC – 50cc 4-Stroke Scooters Diamo – 50cc 4-Stroke Scooters Flyscooter – 50cc 4-Stroke Scooters Ice Bear – 50cc 4-Stroke Scooters Italica – 50cc 4-Stroke Scooters JCL – 50cc 4-Stroke Scooters Jonway – 50cc 4-Stroke Scooters Kandi – 50cc 4-Stroke Scooters Kinroad – 50cc 4-Stroke Scooters KMD – 50cc 4-Stroke Scooters Kymco – 50cc 4-Stroke Scooters Lance – 50cc 4-Stroke Scooters Leike – 50cc 4-Stroke Scooters Linhai – 50cc 4-Stroke Scooters Longbo – 50cc 4-Stroke Scooters Motobravo – 50cc 4-Stroke Scooters Motofino – 50cc 4-Stroke Scooters Motorino – 50cc 4-Stroke Scooters NST – 50cc 4-Stroke Scooters Peace – 50cc 4-Stroke Scooters Puma Cycles – 50cc 4-Stroke Scooters Redstreak – 50cc 4-Stroke Scooters Roketa – 50cc 4-Stroke Scooters Scootstar – 50cc 4-Stroke Scooters Schwinn – 50cc 4-Stroke Scooters SSR – 50cc 4-Stroke Scooters SUNL – 50cc 4-Stroke Scooters Supermach – 50cc 4-Stroke Scooters SYM – 50cc 4-Stroke Scooters Tank Sports – 50cc 4-Stroke Scooters TaoTao – 50cc 4-Stroke Scooters Trailmaster – 50cc 4-Stroke Scooters Veloz – 50cc 4-Stroke Scooters Verucci – 50cc 4-Stroke Scooters Vitacci – 50cc 4-Stroke Scooters Viva – 50cc 4-Stroke Scooters Wolf – 50cc 4-Stroke Scooters Xingyue – 50cc 4-Stroke Scooters ZNEN – 50cc 4-Stroke Scooters 139QMB NARAKU 52.4mm CYLINDER UPGRADE. This is what they call the 100cc kit, but the reality it is a true 52.4mm the largest size you can actually go with real performance by NARAKU. BIG BORE QMB NARAKU CYLINDER KIT RP-NK100.52 Item Nr.: NK100.52 EAN-Code: 4250362410412 cylinder kit Naraku V.2 with head – 90cc – GY6, Kymco 50cc 2V Naraku 90cc Power Racing Cylinder Kit (Ver. 2) – GY6 (50cc 4-stroke) A great 90cc cylinder kit from Naraku. Performance Power Racing 90cc (d=52.4mm) cylinder + head and valves for 4-stroke GY6 engines. eg. – Rex RS450 4-stroke. PARTS FOR GY6 SCOOTERS. Impressive power! So far there haven’t been many cylinder kits for 4-stroke scooters to choose from but now Naraku changes that with the Naraku 90cc cylinder kit. The Naraku Power Racing cylinder (version 2) is the only cylinder available with a 52.4mm bore and with its actual 89cc it has the largest capacity among cylinders for the GY6 engines. The 90cc makes for excellent torque and an impressive increase in engine output. Other manufacturers tend to cheat about the effective swept volume rounding up generously. In order to be able to compare cylinders and swept volume you should always take the bore size as a basis. Included in the kit are an optimized head with maximum intake and exhaust port sizes as well as a modified piston with coated rings. The kit comes with everything you need to simply replace all necessary parts without any further conversions. You can go on using your old carb but make sure to adjust the jetting. An inexpensive alternative to the Power Racing cylinder is the Naraku Sport Cylinder with 52.4mm bore (effective displacement of 89cc) and quick acceleration. Note: Please make sure this scooter engine part fits your particular scooter model. Many scooters have the same name but use different engine parts depending on the year of manufacture. NK100.52 **NOTE: You will need to bore your engine to complete the installation. Please verify first before placing an order. **