Fits all years Grom and Monkey

The DHM Stock Bore High Compression piston has produced more HP than any other stock bore kit, and is the highest compression stock bore piston on the market! It has a high compression dome that is made exclusively for DHM and isn't available anywhere else. It has gone through extensive testing on and off the racetrack and has proven to provide the most power possible from the stock bore.

~13.2:1 compression 52.4mm stock bore piston
Larger ring and skirt oiling holes than other pistons on the market
Larger oil spring to increase oil volume between the oiling rings
Oil ports under the pin holes to keep the wrist pin lubricated
360 Degree skirt design to increase overall strength
Racing piston ring kit with pins and circlips
Valve reliefs that clear valves up to our 27.5/23.5 cylinder head
Includes a new base gasket and head gasket

*Requires NGK CR9E (6263) spark plug (not included)
*Requires 91 or greater octane fuel

**Installing this piston requires setting the ring gaps. If you are not comfortable with this, please have your local shop perform the install. Failure to set the proper piston ring end gap can result in premature failure or seizure of the engine. We recommend an end gap of .007-.009" on the top ring and .009-.011" on the bottom ring.