Transform your Honda Grom or MSX125 with our Big Bore Kit Installation Service, expertly fitted by the leading Grom tuning specialists in the South East — MH MotorsportUK.

This package includes full professional installation of a complete Big Bore Kit, designed to deliver significant performance gains, enhanced torque, and a more responsive riding experience. The kit includes a high-performance camshaft essential for the LIGHT bore-up setup, plus an I-MAP fuel controller to ensure precise fuel injection and optimal engine performance.

For the best results and to maintain stability and reliability, we recommend replacing the muffler/exhaust system when fitting this kit.

This service includes:

• Professional installation by MH MotorsportUK
• Initial tuning and setup for maximum reliability and performance
• Expert advice and aftercare support
• Aluminum cast iron sleeve cylinder
• Displacement: 181cc

　 Bore diameter: φ63

　 Stroke: 57.9mm

• Piston: Casting (3R) specifications
• Compression ratio: 11.1:1 (normal: 9.3:1)
• I-MAP injection controller included
• O2 sensor Feedback canceller included
• Unleaded premium gasoline specification
• full size oil cooler with custom in-house low mounting bracket
• 1.3l of 10w50 oil (increased capacity with new oil cooler)

Important Information:

• This listing includes installation — you’ll need to arrange to drop off your bike at our workshop.
• Collection and delivery services are available for an additional fee. Please contact us to arrange this.
• MH MotorsportUK are the leading specialists in Honda Grom / MSX performance tuning and upgrades across the South East.

Unlock the true potential of your Grom with MH MotorsportUK — precision performance, expertly installed.

*Because it exceeds 125cc, it cannot be used on general public roads.