Italian motorcycle parts and accessories specialist Athena has introduced a new big bore cylinder kit for the Yamaha YZ450F. Designed for riders looking to take their dirt bike to the next level, the kit is a bolt-on application that claims to improve engine efficiency, performance, and response. Compatible with all Yamaha YZ450F models from 2020 to 2022, Athena's bore kits are designed and manufactured in Italy.
According to Athena, the Big Bore Kit can be installed without making any modifications to the crankcase. The kit consists of a lightweight forged piston, aluminum cylinder head with a self-lubricating and anti-seizing coating on the inside, as well as all the gaskets and hardware required for the install. Power gains are pegged at an increase of six horsepower, thanks to the bigger bore which has been stretched to 102 millimeters. Furthermore, the forged piston as well as the reinforced internal walls of the cylinder make for lower friction increasing engine efficiency and lifespan.
The company states that the big bore kit has undergone rigorous bench and track testing and has yielded significant improvements to performance, although Athena doesn't provide the exact figures apart from the six horsepower gain. It also states that the engine's compression ratio is increased slightly, as a result of the upgrade. Athena's Big Bore Cylinder Kit is available for 740.99 Euros, which translates to around $738 USD.
For those looking for a more modest upgrade to their bike, Athena is also offering a standard bore upgrade that follows the same specifications of the stock engine. In this kit, the engine is beefed up for better efficiency and longevity thanks to a forged aluminum piston that features a molybdenum disulfide coating that lowers friction, resulting in improved performance and efficiency. Athena's standard bore kit for the Yamaha YZ450F retails for 547.99 Euros, or approximately $546 USD.