ENGINE (Big Bore Kits, Camshafts and Engine Parts )

Honda Grom Big Bore Kits

Upgrade your Honda Grom's engine with a big bore kit from Hard Racing. We carry the top brands in Grom performance tuning — Takegawa, Kitaco, and Koso — offering displacement bumps from the stock 125cc up to 150cc, 170cc, or 181cc.

Popular Honda Grom Big Bore Options

The stock Honda Grom displaces 125cc. A big bore kit replaces the cylinder, piston, and rings to increase displacement for noticeably more torque and top-end power. Most kits are bolt-on compatible with stock heads, though pairing with a performance camshaft unlocks the full benefit of the larger bore.

Brands We Carry

Takegawa offers 143cc and 181cc Grom bore-up kits with high-compression forged pistons, trusted by racers worldwide. Kitaco makes affordable 150cc and 181cc kits with proven reliability for street use. Koso offers the 170cc 4-valve big bore kit for serious performance gains on 2013–2020 Grom and Grom SF models.

Camshafts & Engine Parts

Complete your Grom engine build with a performance camshaft, head gasket kit, cam chain, or cylinder head. We carry everything you need to build a reliable high-performance Grom engine.

Questions? Call 704-799-2192 or chat with our team. All orders ship fast from our Charlotte, NC warehouse.