Yamaha QT50 60cc Big Bore Cylinder Head & Piston Kit 1979–1987 – 44mm
New aftermarket 44 mm big-bore cylinder, head and piston kit for Yamaha QT50 applications. Matching aftermarket catalogues list this 44 mm / nominal 60 cc top-end conversion for QT50 1979–1987.
Key Details
- Product: Cylinder, head and piston big-bore top-end kit
- Nominal capacity: 60 cc
- Bore: 44 mm
- Standard bore replaced: 40 mm
- Engine type: 2-stroke
- Condition: New
- Type: Aftermarket big-bore conversion / replacement kit
Vehicle Compatibility
| Make | Model | Years | Application |
|---|---|---|---|
| Yamaha | QT50 | 1979–1987 | 44 mm / nominal 60 cc big-bore top-end conversion |
Yamaha / Application Reference Numbers
- PW50 standard cylinder: 4J2-11311-01 / 4J21131101
- Earlier PW50 cylinder reference: 4J2-11311-00 / 4J21131100
- PW50 cylinder head: 4J2-11111-01 / 4J21111101
- Earlier cylinder-head reference: 4J2-11111-00 / 4J21111100
- Cylinder-head gasket: 517-11181-01 / 5171118101
- Cylinder base gasket: 3PT-11351-00 / 3PT1135100
- Cylinder studs: 90116-06418 / 9011606418
- Flange nuts: 95707-06500 / 9570706500
These are Yamaha application/reference numbers for the standard components that this big-bore conversion replaces or interfaces with. The supplied kit is an unbranded aftermarket 44 mm conversion kit and is not described as a Genuine Yamaha part.
Reference Specifications
| Nominal displacement | 60 cc big-bore conversion |
|---|---|
| Bore | 44.0 mm |
| Standard PW50 bore | 40.0 mm |
| PW50 stroke | 39.2 mm |
| Reference cylinder outside width | approximately 51 mm |
| Reference cylinder total height | approximately 87.5 mm |
| Reference cylinder section length | approximately 64 mm |
| Engine type | Air-cooled 2-stroke single-cylinder application |
What's Included
- 1 × 44 mm cylinder block
- 1 × cylinder head
- 1 × 44 mm piston
- 1 × piston ring set
- 1 × piston pin
- 2 × piston circlips
- 1 × small-end / needle bearing
- 1 × cylinder-head gasket
- 1 × cylinder-base gasket
- 4 × cylinder studs
- 4 × stud nuts
- 1 × spark plug
Contents are based on the supplied kit listing and matching 44 mm PW50/QT50 big-bore kit specifications.
Important Fitment Information
Confirm the original engine configuration before ordering. QT50 specification and previous engine modifications can vary, so match the original cylinder, head, stud spacing and gasket profile before fitting. This is a 44 mm big-bore conversion kit, not a standard 40 mm replacement cylinder. Compare the cylinder, stud pattern, gasket shape and top-end components with the engine currently fitted.
Condition
New. Unused aftermarket replacement / upgrade engine components.
Delivery & Returns
- Free UK delivery with an estimated 2–3 working-day service
- 30-day returns, subject to the item being returned in its original condition