Enhance your Honda Grom with the KOSO 4V Head Kit, designed specifically to complement the KOSO 170cc Big Bore Kit. Featuring a unique four-valve configuration, this head increases airflow and combustion efficiency, resulting in improved horsepower and torque. Crafted with a forged piston, stainless steel 24 mm intake valves, and 20 mm exhaust valves, this head kit is engineered for performance enthusiasts seeking maximum engine output.
Built for direct fitment on Honda MSX125 Grom models from 2014 to 2019, as well as the 2019 Honda Z125 Monkey and Z125A Monkey ABS, this kit ensures precise compatibility and optimal performance. The design optimizes airflow dynamics, which translates into stronger acceleration and better throttle response, making it an ideal upgrade for those pushing their bike’s limits.
This product is intended for race use only in California, as it is not legal for use on pollution-controlled vehicles there. It requires the use of an Iridium spark plug for proper operation. Installation of this kit provides a significant upgrade in engine breathing capacity, making it suitable for riders looking to increase power and torque for racing or aggressive riding styles. The durable construction and tailored fitment ensure reliability and consistent performance under demanding conditions.

Features:

• Not legal for use in California on pollution-controlled vehicles, race use only in California - waiver available

• Requires the use of Iridium spark plug

• s a forged piston, stainless steel 24 mm intake valves, and 20 mm exhaust valves

• Designed specifically for Koso 170cc big bore kit compatibility

• Direct fitment for Honda MSX125 Grom (2014-2019), Honda Z125 Monkey (2019), and Z125A Monkey ABS (2018-2019)

Fitment:
2014 Honda MSX125 Grom
2015 Honda MSX125 Grom
2016 Honda MSX125 Grom
2017 Honda MSX125 Grom
2018 Honda MSX125 Grom
2018 Honda MSX125A Grom ABS
2019 Honda MSX125 Grom
2019 Honda MSX125A Grom ABS
2019 Honda Z125 Monkey
2019 Honda Z125A Monkey ABS
2020 Honda MSX125 Grom
2020 Honda MSX125A Grom ABS
2020 Honda Z125 Monkey
2020 Honda Z125A Monkey ABS