OS 0.75 Piston Ring Kit For Yamaha YFB YFM 250 Bear Tracker Timberwolf 1989 2009 ATV
OS 0.75 Piston Ring Kit For Yamaha YFB YFM 250 Bear Tracker Timberwolf 1989 2009 ATV is backordered and will ship as soon as it is back in stock.
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OS 0.75 Piston Ring Kit For Yamaha YFB YFM 250 Bear Tracker Timberw...
Precisely engineered piston ring kit for 250cc ATV engines, designed to restore compression and reliable sealing in 1989–2009 Bear Tracker and Timberwolf family models. The OS 0.75 oversize helps reclaim bore wear, revive lost power, and cut oil consumption by renewing the piston ring seal. This aftermarket replacement delivers a cost-effective rebuild option that keeps trail work and field duties moving without the OEM price tag.
Built to tackle common wear like ring land scuffing, blow-by, and compression loss from long hours in mud, dust, and heavy-duty use, this OS oversize kit re-establishes proper bore clearance and consistent sealing. It’s a dependable choice for riders who demand durable, repeatable performance in tough environments, whether crawling through mud or hauling gear across fields.
Comprehensive Vehicle Fitment
| Manufacturer | Models / Series | Years / Details |
|---|---|---|
| Yamaha | YFB250 Bear Tracker | 1992–2000 |
| Yamaha | YFB250 Bear Tracker (4x4 variants) | 1992–2000 |
| Yamaha | YFB250F | 1992–2000 |
| Yamaha | YFB250U | 1992–2000 |
| Yamaha | YFM250 Timberwolf | 1989–1991 |
| Yamaha | YFM250 Timberwolf (late 1990s–2000s) | 1999–2004 |
| Yamaha | YFM250 Bear Tracker / Bruin variants | 1999–2009 |
| Yamaha | YFM250B | 2005–2009 |
| Yamaha | YFM250X | 1999–2004 |
Product Specifications
| Attribute | Details |
|---|---|
| OEM Reference Part Numbers | 4BD-11610-30-00 |
| Type | Piston Ring Kit (Top Ring, Second Ring, Oil Ring) |
| Manufacturer | Aftermarket Replacement |
| Application | Yamaha YFB250 Bear Tracker / YFM250 Timberwolf (1989–2009) engines |
| Material | Cast Iron alloy rings (monometal construction) |
| Oversize | OS 0.75 mm (+0.75 mm) |
| Ring Count | 3 rings (Top compression ring, Second compression ring, Oil ring) |
| Compatibility Note | Designed for engines with bore sizes compatible with the Yamaha 250cc YFM/YFB family; verify bore measurement prior to install |
OEM & Aftermarket Cross-Reference Information
| Part Number | Brand / Type | Cross-Reference Notes |
|---|---|---|
| 4BD-11610-30-00 | Yamaha OEM | Original equipment reference for YFB/YFM 250 piston ring kit |
| 4BD-11610-00-00 | Aftermarket Replacement | Comparable aftermarket cross-reference to OEM-style kit |
| 710XDS | Wossner (Aftermarket) | Cross-reference for ~71.0 mm bore (OS variations available) |
| 715XDS | Wossner (Aftermarket) | Cross-reference for ~71.5 mm bore (OS variations available) |
| 720XDS | Wossner (Aftermarket) | Cross-reference for ~72.0 mm bore (OS variations available) |
| 725XDS | Wossner (Aftermarket) | Cross-reference for ~72.5 mm bore (OS variations available) |
| 730XDS | Wossner (Aftermarket) | Cross-reference for ~73.0 mm bore (OS variations available) |
What's Included
Inside the box you’ll find the essential rings designed for Yamaha YFM/YFB 250 engines:
- Top Compression Ring
- Second Compression Ring
- Oil Ring
Why Choose This Aftermarket Replacement?
- Direct-Fit Compatibility—engineered to match the bore and ring count of the YFB/YFM 250 family for a straightforward install.
- OEM Cross-Reference Ready—uses standard OEM references and reliable aftermarket cross-refs to simplify sourcing.
- Premium Materials—cast iron monometal rings designed for durable wear resistance and consistent sealing.
- OS Oversize Correction—+0.75 mm oversize restores bore clearance after wear or light honing, helping restore compression
- Comprehensive Ring Set—includes top, second, and oil rings to restore balanced sealing and oil control.
- Cost-Effective Rebuild—an economical alternative to OEM kits without sacrificing sealing performance.
Installation Notes:
- Measure the bore. Verify bore size is within the 71.0–73.0 mm range and confirm that OS 0.75 mm is appropriate for the cylinder before installation.
- Ring orientation. Install the top compression ring with the marked face facing upward; ensure the second compression ring sits in the correct groove as per service manual.
- End-gap and seating. Check ring end gaps after installation and consult spec for OS rings; improper gaps can cause high oil consumption or blow-by.
- Lubrication. Generously lubricate rings, grooves, and cylinder wall with clean engine oil or assembly lube to prevent scuffing on initial startup.
- Ring compressor use. Use a proper piston ring compressor to seat rings evenly into the bore without twisting or bending.
- Cleanliness. Thoroughly clean the cylinder, piston lands, and oil passages before final assembly to avoid abrasive particles causing wear.
Why Upgrade?
Running a worn piston ring kit on these 250cc engines invites compression loss, higher oil consumption, and reduced power. Upgrading to this OS oversize replacement restores sealing integrity and bore clearance, delivering reliable compression, smoother oil control, and renewed performance for trail riding and farm work.
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