Yamaha YZ125 Phathead cylinder head kit 2005-2025

We will restock colors soon. sorry for the delay. 

Yamaha YZ125 Phathead cylinder head kit 2005-2025

Chamber selection:

FX11 - 8.3cc Stock
FX12 -  7.8cc (95+ octane) 
FX13 - 7.2cc (100+ octane)

Phathead Kits include a head shell with one combustion chamber, two sets of o-rings, 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.   

One of the main benefits of the product is the replaceable combustion chamber which are available in a range of compression options.

Suggestions : Swap chambers to adjust performance for a variety of riding conditions and track types or keep a spare in case of engine failure.