DHM 149cc Big Bore Cylinder kit for 2022+ Honda GROM

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About DHM 149cc Big Bore Cylinder kit for 2022+ Honda GROM
After over a year of development, the big bore 149cc kit is ready to go!   Kit includes:
  • 55mm Forged Piston with RK Ring kit
  • 55mm Sleeved cylinder
  • Base and head gasket set
  • NGK Spark Plug
This kit provides a significant horsepower and torque increase across the entire rev range. Expect gains of 30% in the midrange over a bike with intake, exhaust and cam, and double the horsepower of a stock bike at 8500rpm. We recommend running it with our S1 camshaft along with an aRacer MiniX and AF2 combo for tuning. Or PV3 with Auto tune. ECU flashes are not yet available but we are expecting to have them ready around the end of July Install Notes:
  • Two base gaskets included. Use both copper and paper gaskets for pump fuel, use only the copper gasket if you are running race fuel.
  • An NGK CR9E spark plug must be used
  • Ring gaps must be set during install, we recommend .011" on the upper ring and .013" on the lower ring
  • 91 octane is the bare minimum, and 93 is preferred.
  • Set aRacer spark advance timing to -6 across the entire table when using pump fuel. Spark angle can be adjusted during dyno tuning.
  • Honda injector 16450-KZY-701 is the recommended injector for this kit.


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