MSX 125 Grom

Technical

The MSX125 Grom has a new, 125cc two-valve air-cooled engine, with 50mm bore and 63.1mm stroke, and compression ratio of 10.0:1. Peak power of 7.2kW arrives at 7,250rpm, with peak torque of 10.5Nm at 5,500rpm.

Just like the previous design, the MSX125 Grom’s engine packs a perfect blend of zippy roll-on performance with useful, accessible all-round ability. Really, this unit all about fun of twisting a throttle, but one major upgrade that riders will appreciate is the application of a 5-speed gearbox (rather than 4-speed) to spread the ratios further and give more relaxed, higher-speed cruising. Top speed goes from 92km/h to 94km/h.

Manual clutch operation still imparts a full-sized motorcycle experience, while the 15T gearbox sprocket, 38T final drive sprocket and 12-inch wheels deliver lively around-town response plus the ability to travel slowly in a high gear – perfect for threading easily through tight traffic.

It’s also economical, returning 66.6km/l (WMTC mode) by using low-friction technologies, such as an offset cylinder and roller-rocker arm for the valve gear. Sophisticated PGM-FI guarantees highly efficient combustion, and works in conjunction with both air intake and exhaust to deliver an involving experience at the throttle. A large, 2.5L airbox and panel-type, wet paper filter provide reliable and quiet airflow; the filter itself has a life of 10,000 miles. The exhaust downpipe and muffler are now two separate parts.

The MSX125 Grom is homologated for EURO5, which from January 1st 2020, introduced significantly stricter engine emissions standards compared to EURO4. These requirements include substantial reductions in permitted carbon monoxide emissions, an over 40% decrease in total hydrocarbon emissions, tougher misfire detection and the introduction of a particulate matter limit.

Chassis

The MSX125 Grom’s well-proven chassis is essentially unchanged during its 2021 makeover, and the original priorities of design remain relevant: provide the base for a practical bike that new riders could use – and park – with ease in an urban environment, but be just as useable and enjoyable out of town, and also readily accept a pillion.

A steel mono-backbone frame ensures the MSX125 Grom’s core strength. Its rigid, square-section tube joins the headstock directly to the swingarm pivot plates and every other part in effect hangs visibly from the frame, greatly contributing to the minimalist look. Specifically tuned vertical/horizontal rigidity and flex in the swingarm pivot and engine hanger plates provides the perfect balance of comfort and confidence.

The frame structure also enables efficient storage of PGM-FI-related components and electrical parts inside the tank cover and fuel capacity is increased (6.0L). Wheelbase is a snug 1200mm, with rake and trail of 25°/84mm. Kerb weight is reduced to 103kg. A low 761mm seat height makes the MSX125 Grom very manageable; its size also ensures that motor home owners find it easy to load/unload, transport and use.

Suspension front and rear delivers ‘beyond class’ quality. The 31mm USD fork reduces unsprung weight and, thanks to the pistons’ greater pressure-bearing area (compared to a standard telescopic fork) offers improved damping feel throughout the stroke. The top and bottom yokes are full-sized, further enhancing handling and rider feel while a lightweight and robust single rear shock operates a simple and tough H-shape, 50mm x 25mm steel box section swingarm.

Fundamental to the MSX Grom’s form and function are its 5-spoke (re-styled) 12-inch cast aluminium wheels, which feature wide 2.5-inch rims. Front 120/70-12 and 130/70-12 rear tyres also inject dynamic looks and performance. Hydraulic dual piston front (finished in gold) and single piston rear brake calipers work front 220mm and rear 190mm discs. The ABS system operates through an IMU.