186cc Big Bore

and Oil Cooler Kit

Monkey 125 and Grom
(2021 and older only)

186cc Big Bore Kit Performance (64mm) and Oil Cooler Kit:

– Ceramic coated all aluminum cylinder (no steel sleeve)
– Lightweight 64mm piston with rings, pin, & clips
– Head gasket kit
– Oil Cooler Kit

This is the biggest  big bore kit on the market for your Grom or Monkey 125! The all aluminum ceramic coated cylinder is lighter than a steel sleeved aluminum cylinder, reduces friction (increasing power), improves sealing, and provides better heat transfer (runs and cools down quicker).This new big bore kit will provide the extra power to make your new Grom or Monkey a lot more fun to ride!  High quality parts and requires no machining to the cases.

The Oil Cooler Kit is a high quality accessory designed to help the Honda horizontal engine keep cooler. Air-cooled engines run hotter when modified (with big bore kits) and/or subjected to heavy loads such as racing use. This kit will help the engine’s durability and reliability by circulating the engine oil through a cooler reducing the engine’s oil temperature.

There are no installation instructions, but if you can replace your piston, you can install this kit as the parts are installed in the same manner as the OEM parts.  However, its recommended that a professional install this kit.  It also must be used with an aftermarket fuel controller to prevent a lean condition and damage to your engine.

This product is legal for closed-course competition use only; for racing vehicles (a competition vehicle not used on public highways). Intended for off-road use or race purposes; may not meet regulations of pollution controlled roads or highways. Not legal for vehicles registered and use in California.