Increased cubic capacity for Honda’s range-topping SH brings with it faster top speed and improved acceleration. The engine is also now EURO5 compliant. A refined frame design saves weight while all-new bodywork evolves the style and includes LED headlight, taillight, indicators and LCD meter panel. There’s also now a USB Type-C socket under the seat.

1. Introduction

Look around Europe’s capital cities and two letters will be constantly, obviously, on the move around you: SH. Over a million SH scooters have been sold in Europe over the last 36 years, earning the SH tag the status of a brand-within-a-brand, underpinned by Honda’s famed build quality and reliability.

The SH300i, with its compact, flat-floored step-through design and 16-inch front and rear wheels carried all of the SH signature touches and packed something extra – a powerful engine delivering maximum response for both city and highway use.

It became the first Honda to gain EURO4 compliance back in 2015; at the same time its engine got a boost in torque output and fuel efficiency. Its look, too, was made more muscular while the chassis received revisions to expand storage space and maintain its razor-sharp handling. In 2019 it gained Honda Selectable Torque Control (HSTC) and Smart Key operation.

For 2021 the story continues: the new SH350i gains cubic capacity, thus power and torque plus an elegant re-style, further cementing its position as the perfect all-round scooter.

2. Model Overview

A 50cc capacity increase injects 16% more peak power, to 21.5Kw, and the SH350i’s new eSP+ engine is significantly stronger all the way through the rev-range, delivering faster acceleration and increased top speed. It’s also EURO5 compliant.

The frame has been revised to save weight, and completely refreshed styling is a sleek evolution of the SH formula of compact, usable practicality – easy to both ride and park. An under-seat USB socket replaces the ACC charger, and there’s a new LCD dash.

The 2021 SH350i will be available in the following colour options:

Mat Carnelian Red Metallic

Mat Ruthenium Silver Metallic

Pearl Cool White

Black

3. Key Features 

3.1 Engine

• 330cc engine puts out an extra 3Kw peak power @ 7,500rpm and 4.8Nm more torque at 5,250rpm.
• ‘enhanced Smart Power+’ technology ensures fuel economy of 30km/l (WMTC mode), with EURO5 compliance
• 10% lighter crankshaft
• Throttle bodies increased in size to 36mm (from 34mm)
• Inlet valves’ diameter increased to 28mm (from 27mm)
• New piston oil jet to improve cooling and combustion efficiency
• Revised intake and exhaust ports improve efficiency
• Redesigned muffler, with only two chambers
• Hydraulic cam chain adjuster and scavenger pump to reduce internal friction

The SH350i’s new ‘enhanced Smart Power+’ engine achieves both high environmental performance and strong output characteristics through comprehensive adoption of technologies for friction reduction.

Thanks to the extra 50cc capacity (to 330cc from 279cc, with no gain in overall kerb weight) the liquid-cooled, fuel-injected SOHC four-valve unit’s peak power rises from 18.5kW to 21.6kW @ 7,500rpm, with maximum torque increasing to 32Nm @ 5,250rpm. The dyno graph comparison graphically displays the whole picture showing how both power and torque rise considerably from 3,500rpm up. From a standing start, the SH350i will hit 200m 0.7s faster, at 10.2s.

To earn the extra ccs, the bore goes from 72mm to 77mm while stroke increases to 70.7mm. Compression ratio is set at 10.5:1. To make use of the increased capacity, the length and timings of the valve lifts have been optimised. Compared to the previous model, the closing of the inlet valve and the opening/closing timings of the exhaust valves have been delayed by 5°. The lift amount has also been increased by 0.3mm. The timings of the inlet valve openings remain unchanged.

The crankshaft has also been redesigned and is now 10% lighter. This has been achieved without any change to the dimensions of the journals, while still maintaining the strength and rigidity required to transmit the higher output. Roller-type rocker arm, plain journal crank bearings and sealed crankcases deliver long-term reliability together with strong performance. To enhance piston cooling, an oil jet, as used on the CRF450R, sprays oil right to the back of the piston, advancing ignition timing and improving combustion performance. Oil capacity is 1.85 litres.

A revised intake sees throttle bodies increase to 36mm from 34mm, with inlet valves increasing 1mm to 28mm, increasing efficiency. Air is supplied via a 5.5 litre airbox. Intake and exhaust ports have also been completely redesigned. The intake port now draws air in more efficiently, utilising a strengthened tumble flow within the cylinder for more consistent fuel combustion. Exhaust gases are now expelled via a straight exhaust port, rather than the curved port of the previous design, further improving efficiency.

To reduce exhaust gas resistance, the new muffler now consists of two distinct chambers rather than three. Improvements to the pipe connecting the expansion chamber as well as the size and location of the catalyser also improve gas flow and purification.

Internal friction is reduced through a 5mm offset cylinder, the introduction of hydraulic cam chain adjuster and the use of a scavenger pump. Used on high performance machines, the pump lowers the internal pressure within the engine, reduces oil agitation and decreases pumping losses and internal rotational friction.  A newly adopted balancer shaft further reduces vibrations and contributes to a smooth enjoyable ride.

An automatic centrifugal clutch works a V-Matic transmission (with ratios set for fast low speed reaction and smart acceleration) and belt final drive. Through the 2021 update the engine cover has been redesigned to complement the new bodywork.

The SH350i’s engine is equipped with Honda Selectable Torque Control (HSTC). The system detects any difference between the front and rear wheel speeds, calculates the slip ratio and then controls engine torque via the fuel injection to regain rear wheel traction. HSTC can be switched ON-OFF via a switch on the left handlebar. A ‘T’ indicator in the digital display flickers when the system is working to manage grip.

The engine is also now homologated for EURO5, which from January 1^st 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.

Fuel economy is a frugal 30km/l (WMTC mode); the 9.1L tank capacity gives a potential 270km+ range.

3.2 Styling & Equipment

• SH style evolves while maintaining signature flat floor
• USB Type-C socket under the seat
• New LCD instrumentation
• Emergency stop signal function warns other road users of sudden braking 

The SH350i is a scooter that instantly defines its presence on the road, marking out its premium SH lineage with brand-new design following the look of the best-selling younger sibling the SH125i, with the styling key words of ‘muscular’ and ‘surface tension’. Its new ‘face’ sets it apart: the LED headlight now features a central main beam splitting dual dip beams, while position lights reside above on the handlebar nacelle to create a sleek, contemporary frontal signature. The redesigned LED taillight and indicators sit neatly at the rear, between a passenger grab rail now constructed from aluminium.

Of course, as an SH, function is as important as form. The riding position maintains the ability to support a wide range of rider sizes and delivers a relaxed, upright stance and great all-round vision. Total machine length is 2160mm, with width of 742mm and height of 1161mm. Minimum ground clearance is 131mm.

There’s room for a full-face helmet under the seat, and the seat height itself an easy-to-manage 805mm (just 5mm more than the SH125/150). There’s also now a USB Type-C socket for easy charging of a mobile device. The standard SH flat floor (435mm wide) makes loads easy to carry as well as aiding the rider step on and off. A foldable utility hook on the front panel adds convenience.

A new LCD dash presents all warning lights – including HSTC and ABS operation – neatly around a central digital speedo/odometer display. All operations on the dash are carried out via A/B buttons on the left handlebar.

The front and rear indicators of the SH350i have a new auto-cancelling Emergency Stop Signal feature. Once the ABS recognises hard braking is in process, the hazard lights flash to warn other road users.

Adding to the convenience of a busy life on the move is the Smart Key which – as well as controlling the main ignition switch knob and compartment locking – can also manage the optional 35L top box. With the Smart Key in the rider’s pocket the box is unlocked, and automatically locks when the rider walks away. It can also be locked from the key.

3.3 Chassis

• Steel underbone frame refined to save weight
• 35mm telescopic forks and twin rear shock absorbers
• Stability from 16-inch front and rear wheels

The SH350i’s well-proven chassis is designed to deliver agility and composure in all riding situations. For the new model, revised pipe diameters, wall thicknesses, and materials of frame component parts improve high speed stability and comfort, while actually saving 1kg in weight of the frame.

Supple bump absorption is provided by 35mm telescopic forks, twin rear shock absorbers, cast aluminium swingarm and an Oleo link system mounted underneath the engine to assist handling feel and bump absorption.

Rake and trail are set at 27°5’/99mm with wheelbase of 1452mm and the handlebars feature a 45° turn radius from centre. Kerb weight is 174kg.

Tyres are 110/70-16 at the front and 130/70-16 at the rear; two-channel ABS operates 256mm single disc brakes at the front and a 256mm single disc at the rear.

4. Accessories 

A range of Genuine Honda Accessories are available for the SH350i. They include:

35-litre Smart top box & rear carrier kit

Windshield & knuckle visor set

Heated grips

Scooter blanket

For more information on Honda Motorcycles UK visit www.honda.co.uk/motorcycles.html

5. Technical Specifications

All specifications are provisional and subject to change without notice.

*Please note that the figures provided are results obtained by Honda under standardised testing conditions prescribed by WMTC. Tests are conducted on a rolling road using a standard version of the vehicle with only one rider and no additional optional equipment. Actual fuel consumption may vary depending on how you ride, how you maintain your vehicle, weather, road conditions, tire pressure, installation of accessories, cargo, rider and passenger weight, and other factors.

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