Athena

YZ 85 big bore kit with modular cylinder head

Athena has announced an addition to its big bore kit programme for the Yamaha YZ 85 (2019/2020).

The kit increases the displacement to 105 cc and significantly improves the original engine’s performance and efficiency - also guaranteeing extreme reliability and optimal sliding properties.
In addition to the cylinder and the complete piston, the big bore kit contains the modular head and all the gaskets needed for assembly. The Athena cylinder kit can be installed without any changes to the motorcycle crankcase and without having to replace the original engine components.

All the components of the kit have been developed to withstand the highest temperatures, pressures and stress. Athena carefully selects the most suitable materials for each application, such as the cylinder head insert specifically made of bronze - not of aluminium like the original.
This modification ensures better thermal stability even at high temperatures.
A special power valve system allows for higher performance at medium and low revs - horsepower and torque. The cylinder in this new kit is made of aluminium alloy and includes a nickel-silicon coating on the sleeve - this ensures ideal sliding properties (reduced friction and stiction) and guarantees better distribution of the clamp load compared with the original design thanks to the use of six equidistant studs.
The inner bronze dome in the modular cylinder head ensures maximum flexibility in customising the compression values.

ATHENA
www.athena.eu