Grom Bore Kit

The TBparts 149cc big grom bore kit is the ultimate upgrade for your new 2022 Honda grom/Honda monkey 125. This kit increases compression and provides more power for a great price. It includes an aluminum ceramic coated cylinder, a 61 mm forged piston with rings, pin and banjo bolts as well as a camshaft and all necessary gaskets. This kit requires no boring of the cases and works with the stock head. This kit is also recommended with a performance intake and exhaust to maximize power. A fuel controller is also recommended to prevent a lean condition and engine damage.

Grom Bore Kit: Installation Tips and Performance Gains

This product may not be legal for use on public highways (Requires a flash/tune by a professional to comply with California emissions regulations) and is intended for closed-course competition only.