This is a quality replacement Crankshaft with Bearings and Connecting Piston Rod for the GY6 50, 4 stroke, 139QMB, engine for scooters, quads, ATVs and buggies. Chinese 50cc crankshaft fits several makes & models. Please use the pictures and measurements to best match your crank. 16 tooth oil pump drive gear Over Length: 24cm [9.45"] Bearing size/model: 20 X 47 X 14 [6204] Bearing size/model: 17 X 42 X 12 [6203] Sprockets: 17 teeth each Spline count on end of shaft: 26 spline Thread size on tapered end: M10 x 1.25 Thread size on straight end: M12 x 1.25 Please compare to your old part before ordering. COUNT THE TEETH! OLDER MODELS USUALLY HAVE 16 TEETH, WHILE NEWER MODELS WILL HAVE 22! Known to fit GY6-50 engines. Fits: Gator 50 Baja, JMStar, Jonway, Lance, NST, Roketa, Sunl, Tank, TNG, Vento, VIP and many others.