{"product_id":"universal-parts-qmb139-cylinder-head-kit-39-47-50mm","title":"Universal Parts QMB139 Cylinder \u0026 Head Kit | 39\/47\/50mm","description":"\u003cp\u003eComplete cylinder and head kit for QMB139 4-stroke 50cc engines. Choose from 39mm (stock), 47mm (72cc upgrade), or 50mm (81.3cc upgrade) bore from the drop-down. Includes everything needed for a full top-end rebuild. Note: larger bore sizes may require engine case modification. Kit includes: complete cylinder head, cylinder, piston, rings, piston pin, circlips, head gasket, and base gasket. Cylinder bore: 39mm (stock) \/ 47mm (72cc) \/ 50mm (81.3cc) — select at checkout Cylinder sleeve OD: 45mm (39mm bore) \/ 52.8mm (47mm bore) \/ 53.95mm (50mm bore) Wrist pin diameter: 13mm Total piston height: 34.4mm Compression height (wrist pin center to piston top): 17.25mm Intake and exhaust valve length: 64mm Non-emissions head Weight: 4.75–5 lbs (varies by bore) Compatible Engine: QMB139 (139QMB) 49cc \/ 50cc 4-stroke Genuine Buddy 50, RoughHouse 50, Rattler 50, and other QMB139-powered scooters Note: Larger bore sizes (47mm and 50mm) may require modification to the engine case to accommodate the larger cylinder. For off-road and closed-course competition use only. Not intended for use on public roads. California Prop 65 Warning: www.p65warnings.ca.gov\u003c\/p\u003e","brand":"universal parts","offers":[{"title":"Default Title","offer_id":48045953974459,"sku":"151-242   50","price":84.0,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0719\/1340\/6651\/files\/447026.jpg?v=1783061028","url":"https:\/\/thriftyscooters.com\/products\/universal-parts-qmb139-cylinder-head-kit-39-47-50mm","provider":"Thrifty Scooters","version":"1.0","type":"link"}