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KOSO Honda Grom 170cc 4 Valve Big Bore Cylinder Kit with Forged Piston

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From: $13.00

To: $2,979.93

Price as configured: $0.00

Koso Grom 125 61mm Big Bore Cylinder Kit with 4 Valve Cylinder Head is probably one of the best big bore kit available on the market for the Grom.

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Price as configured: $0.00



Koso Honda Grom 4 valve head and 61mm big bore cylinder kit with a forged piston. This is a completely newly designed head using a pair of 24mm intake/21mm valves exhaust valves with matching large intake and exhaust port.  This Koso 4 Valve can produce up to 23-26hp vs. stock 8-9hp. This is a performance engine part, there are no returns on performance parts or individual pieces.

Fuel tuning is required before you can hit the streets with this kit.  We recommend getting the aRacer DG1 Multi-Function Display & AF1 Wideband Combo Kit. 

Additional Info

Additional Info


Koso Honda Grom 4Valve Head with 61mm Cylinder Kit

  • Koso 4V Cylinder Head
  • Koso Camshaft
  • Koso Intake Manifold
  • Koso 34mm Throttle Body
  • Koso 61mm 4V Forged Piston 
  • Koso 61mm Ceramic Coated Cylinder
  • Honda PCX150cc Injector
  • aRacer RC Super or Mini 5 Fuel Controller
  • Spark PlugNGK CPR9EA-9 
  • Compression Ratio: 12.3:1
  • Cylinder Displacement: 169.2cc
  • Power: +25hp
  • RPM Redline: 12,500RPM
  • Only use +91 Oct
Brand Koso


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