PISTON KIT YFM YFB250 71.00, WOSSNER FORGED 8659DA 92-01

The Wossner 71mm Bore Piston Kit (Part No. 8659DA) is a high-performance forged piston designed for Yamaha YFM250 Timberwolf, YFB250 Bear Tracker, Bruin, and Big Bear models. Engineered for strength and durability, it optimizes heat transfer within the combustion chamber and features an elliptical design to ensure even load distribution, reducing localized pressure and preventing piston collapse. Manufactured in Germany, this piston maintains the OEM compression ratio for reliable engine performance.

Features

• High-strength forged piston construction
• Optimized heat transfer for improved combustion efficiency
• Elliptical design for even thrust load distribution
• Manufactured in Germany

Specifications

• Bore Size: 71mm
• Actual Bore Diameter: 70.94mm
• Compression Ratio: OEM
• OEM Compression Ratio: 9.50:1
• Displacement: 229cc
• Stroke: 58.00mm
• Clearance: 0.06mm
• Dome Volume: -4.70cm³
• Compression Height: 23.80mm

Cross-Reference OEM Part Numbers

• Lock P/N: CW16
• Pin P/N: WP041
• Ring Set P/N: 710XDS

Vehicle Fitments

• Yamaha YFM250 Timberwolf (1990-2000)
• Yamaha YFB250 Bear Tracker (2000-2004)
• Yamaha Bruin (2005-2006)
• Yamaha Big Bear (2007-2009)

Dispatch Times

Local Stock: Dispatches in < 24 hours

Parts showing as available at our Warehouse in Gorey ship the same business day if ordered before 1pm. 

Supplier Stock: Dispatches in 2-4 Days

Parts showing as available at our Supplier Warehouse are ordered from our supplier and delivered to us before we can dispatch. More info is available on this page under "Stock Availability".

OEM Special Order: Dispatches in 3-10 Days

This website does not have access to live stock levels from our OEM Suppliers. In most cases the parts will be available but in the case of backordered parts we will notify you. We receive parts from Yamaha in 3-4 days, All others including Honda, Suzuki, Kawasaki, Polaris please allow 7-10 days for us to receive the parts. 

Delivery Times

Ireland & Northern Ireland:

1-2 Days using GLS/An Post

Germany, France, Netherlands, Belgium:

3-5 Days using GLS/Fedex

Italy, Spain & Other EU Countries:

4-7 Days using GLS/Fedex