A grom bore kit is one of the most cost-effective ways to add more power to your new Honda grom or monkey. TBparts offers a complete 186cc big bore kit for the Honda Grom & Monkey 125 that includes the cylinder, cam, (optional oil cooler & lines), oversized valve kit, and all necessary gaskets. This cylinder has an aluminum ceramic coated finish which reduces friction, improves heat transfer, and increases seal life. This allows for a high compression ratio of 11.5 to 1. This kit requires no boring of the cases – just bolt on, tune (not included), and go!

Grom Bore Kit: How to Choose the Right Kit for Your Grom

This product is intended for closed-course competition use only. It must be used with a performance intake & exhaust, and a fuel controller to prevent a lean condition and engine damage.