Wossner Forged Piston Kit 69.00mm Bore – Yamaha YZ250 / WR250 (1988–1991)

This Wossner forged piston kit is designed for Yamaha YZ250 and WR250 models from 1988 to 1991. With a bore size of 69.00 mm and a piston diameter of 68.94 mm (+1.00 mm oversize), it is built for high-performance 2-stroke applications. The forged aluminium construction ensures high strength and durability, while the elliptical profile allows even load distribution during thermal expansion, improving reliability and reducing wear. Manufactured in Germany for precision and consistency.

Features

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  Forged piston construction for maximum strength and longevity

  
  


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  Designed to promote optimal heat dissipation from the combustion chamber

  
  


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  Elliptical design distributes thrust loads evenly, minimising stress concentrations

  
  


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  Precision-engineered and manufactured in Germany

  
  

Specifications

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  Bore Size: 69.00 mm

  
  


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  Piston Diameter: 68.94 mm

  
  


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  Engine Displacement: 246 cm³

  
  


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  Stroke: 68.00 mm

  
  


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  Clearance: 0.06 mm

  
  


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  Compression Height: 36.00 mm

  
  


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  Compression Ratio: 2-stroke (Wossner and OEM)

  
  

Cross-Reference Wossner Part Numbers

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  Piston Kit: 8134D100

  
  


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  Lock: CW18

  
  


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  Pin: WP033

  
  


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  Ring Set: RSB6900 x 2

  
  

Vehicle Fitments

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  1988 Yamaha YZ250

  
  


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  1988 Yamaha WR250

  
  


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  1989 Yamaha YZ250

  
  


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  1989 Yamaha WR250

  
  


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  1990 Yamaha YZ250

  
  


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  1990 Yamaha WR250

  
  


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  1991 Yamaha YZ250

  
  


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  1991 Yamaha WR250