APEX TECHNICAL INNOVATIONS CYLINDER HEAD KIT, YAMAHA YZ125/YZ125X 05-25

The SX/XC dome gives a big midrange boost with more power throughout the power curve. It is best suited to tight tracks with lots of jumps out of corners and woods riding.

The MX dome greatly improves top end power and overrev. This dome works best on fast, flowing tracks. All three domes feature combustion chambers that are fully optimized (compression ratio and MSV) for their specific riding conditions and have a nominal squish clearance of 0.035”. The OEM cylinder head leaves a lot to be desired, and it’s large squish clearance can lead to jetting woes, detonation, poor fuel economy and throttle response, and less power. The Apex Technical Innovations head solves all of these issues while giving you an increase in performance where you need it most. All three of our standard domes are designed to run on pump gas, but we can accommodate requests for race gas domes or for those at high altitude.

Finally, the two piece design allows for higher coolant volume and flow was specifically designed to remove heat as efficiently as possible. Combine this with the higher thermal conductivity of billet 6061 aluminum vs billet 7075 aluminum and cast aluminum alloys, and you have a recipe for a powerful, usable, and reliable engine.

Note: this kit contains one replacement gasket set and one dome sealing o-ring per dome.

Kits we offer come with one dome only. Multiple domes, colors and custom domes can be purchased by contacting us.