Yamaha Athena YZ125 144cc 58mm Big Bore Cylinder Phathead version 1998-2000 and 2001-2023

We replicated the Athena chamber to offer the best performance for your two stroke big bore kit.  Athena YZ125 58mm 144cc big bore compatible.  Use the Athena Big Bore Gasket. 

Phathead Kits include a head shell with one combustion chamber, cylinder head nuts, copper washers, some stickers for your bike and tool box and installation instructions..

Phathead cylinder heads are made of 6061 T6 billet aluminum.  The material is stronger and transfers heat better than cast aluminum.  The two piece design allows an increase in coolant flow as well as surface area which improves cooling for better consistency and performance.