This upgrade really woke up my Grom, David was great and answered all my questions and still continues to do so after we did business, not many vendors do that. Thanks now im putting my order in for the same upgrade for my 2020 grom
La communication avec le vendeur est très facile et la traçabilité du produit irréprochable. Je suis du Québec et je ferais affaire avec DHM pour un autre envoie c’est sur ;)
A must buy if you are going to daily drive a monkey or grom
I bought this a week ago has not posted it after spending a lot on postage and ive been emailing David for the past three days with no response, just be nice to know whats going on i now just want a refund, feel let down.
After doing the research, this piston seems to have the highest compression available for the Grom. Additionally, it's been optimized in many ways over the stock piston that piqued my interest. Dave was a pleasure to communicate with and offered quick feedback for any questions I had. I did my first post-install head cycle just now and everything seemed A-Okay.
DH Motoring Stock Bore Racing Piston (Gen 2)
The DHM Race-spec stock bore 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 us and isn't available anywhere else. It's gone through extensive testing on 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 27.5/23.5 cylinder head valves
Includes a new base gasket and head gasket
Requires NGK CR9E (6263) spark plug
Requires at least 91 octane fuel
Over the past 6 years we've raced with and tested over a dozen different stock bore pistons. Using our experience on the racetrack we've now designed and produced the most competitive and reliable stock bore piston on the market. We targeted increased lubrication while also pushing the compression limits for pump fuel and ended up with what we feel is the most refined 125cc piston available. By enlarging the oiling holes that feed the oil spring channel and skirt, the piston stays well lubricated at all RPM which allows for extended high RPM use. Valve reliefs have been sized to allow the largest valves possible with the stock bore and they have been cut deep enough to ensure compatibility with even the highest lift cams on the market.
**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. Unknown Overland does a great job of explaining this in the video below.