Unleash all the power your Honda GROM can handle with the Koso 170cc Big Bore kit. 61mm bore, 11.5:1 compression ratio forged piston/ring kit (premium fuel required). Top end gasket kit and banjo bolts.
Direct bolt on , no other modification needed including electronic injection .
The ECU ( PCM , etc. ) will compensate for the extra cc even with a full exhaust .
Good buy .
Cylinder should come Black so you'll have to spray paint it.