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GhostBikes.com£917.49Visit shop Athena Silver P400485100029 - Big Bore Race Cylinder Kit For Yamaha Yz125 1997-2004
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The Athena 144cc Big Bore Cylinder Kit is designed for Yamaha YZ 125 owners from 1997 to 2004 who are looking to significantly increase engine displacement and power output. This kit provides a noticeable boost in torque and horsepower, making it an excellent choice for competitive riders or enthusiasts seeking a more dynamic throttle response; however, it requires precise mechanical installation and proper engine break-in procedures to ensure long-term reliability.
| Model Part Number | P400485100029 |
|---|---|
| Brand | Athena |
The Athena 144cc kit typically includes the cylinder and head; please verify the specific contents of your packaging for the piston kit, as it is often sold as a complete top-end package.
While the stock exhaust may work, you will likely see the best performance gains by using an exhaust system tuned for the 144cc displacement.
Due to the 14.0:1 compression ratio, it is recommended to use high-octane race fuel to prevent pre-detonation or engine knocking.
This kit is intended for closed-course competition use and may not comply with emissions regulations for public road use.
No, this specific kit is engineered for the 1997-2004 Yamaha YZ 125 models only.
Verify that the cooling system is bled of all air pockets and ensure the jetting is not too lean, as lean mixtures increase engine heat.
Check carburetor jetting; the increase in displacement may necessitate a richer main jet or needle adjustment to match the increased airflow.
Inspect the head gasket seal and ensure cylinder head bolts are torqued to the specific manufacturer recommendations.
This kit is exclusively compatible with Yamaha YZ 125 models produced between 1997 and 2004. Installation involves a complete top-end teardown; it is strongly recommended that this be performed by a qualified technician or an experienced mechanic.
