The Honda Grom is powered by a compact 125cc air‑cooled, four‑stroke, single‑cylinder engine with electronic fuel injection and a four‑speed transmission.
Engine basics
At the heart of the Grom is a small, air‑cooled four‑stroke powerplant designed to keep the bike approachable for new riders while delivering enough output for city riding. The engine uses Honda’s electronic fuel injection system to promote smooth operation across varying loads and temperatures, reducing the need for carburetor tuning and improving cold-start reliability.
Its layout is straightforward: a single cylinder, with a simple valvetrain and a compact footprint that helps the Grom remain light and easy to maneuver. This combination also supports good fuel economy and low maintenance costs—factors that have helped the Grom appeal to urban commuters and aftermarket enthusiasts alike.
Core technical specifications
Here are the core technical specifications of the Grom’s engine:
- Displacement: about 125 cc (123.7 cc) class
- Configuration: single-cylinder
- Cooling: air‑cooled
- Valvetrain: SOHC with two valves
- Fuel system: electronic fuel injection (PGM‑FI)
- Transmission: 4‑speed manual
- Bore x Stroke: 52.4 mm × 57.8 mm
- Compression ratio: around 9:1
These elements together make the Grom’s engine a compact, reliable, and economical powerplant that suits its role as a lightweight, entry‑level street bike with a bit of performance edge for urban riding.
Summary
In short, the Honda Grom uses a small, air‑cooled, four‑stroke single‑cylinder engine with electronic fuel injection and a four‑speed transmission. Its design emphasizes simplicity, efficiency, and ease of use, while still delivering spirited performance appropriate for city streets and weekend rides. The engine’s compact dimensions and low maintenance requirements have helped the Grom maintain popularity since its introduction, with ongoing updates kept focused on reliability and rideability for a broad audience.