The AS 531 4T MK is a professional petrol 53 cm mower built for contractors and grounds teams who need strong collection and dependable handling across mixed grass and uneven ground. It runs the Kawasaki FJ180V KAI engine, giving consistent power in damp or thicker growth while keeping fuel use sensible over a full day’s work.
This model is designed for real commercial conditions: tight areas around buildings, sloped lawns, churchyards and sites where a clean, collected finish matters. With its blade clutch, safety brake and limited-slip differential, the AS 531 4T MK offers reliable control and a solid cut without the fuss of a domestic mower.
What the AS 531 4T MK Is Built For
The AS 531 4T MK is designed as a dependable, everyday contractor mower for sites where a collected finish is essential. It handles the sort of mixed conditions that define commercial work: damp morning grass, uneven ground, tight corners, banks, kerbs and areas around gravestones or benches. The Kawasaki engine delivers steady power without surging or bogging down, and the deck maintains strong airflow so the bag fills cleanly even when the grass is slightly wet.
This model fits the gap between domestic machines that struggle under heavy use and the more specialist slope mowers in the AS range. It’s light enough to handle confidently on awkward sites but strong enough to survive kerb edges, manhole lips and the wear that comes from daily use on multiple properties. For most contractors, it serves as the main walk-behind mower in the van.
Who This Model Suits
- Landscapers and contractors needing a reliable 53 cm collector for mixed sites.
- Schools, churchyards, parks and housing developments where neat collection matters.
- Grounds teams working around paths, bollards and confined areas.
- Operators who prefer petrol power but still want safety features and clean handling.
Why It Works Well in Real Commercial Jobs
The automatic limited-slip differential gives both rear wheels meaningful drive, which is helpful on banks and uneven ground where a standard mower would spin out. The parking brake engages the moment the blade clutch is released, keeping the mower under control on slopes or when repositioning. The blade clutch also means you can stop the blade without shutting the engine off, which saves time when emptying the bag or clearing debris.
Operator comfort is another strong point. The open V-handlebar layout leaves the controls clear and easy to reach, so the right hand can manage drive, brake and blade clutch while the left hand adjusts speed. The vibration damping and rubber-mounted handlebar reduce fatigue across long shifts, and the swivelling setup makes working along walls, fences and vehicles far easier than with a fixed bar.
Where It Sits in the AS Range
In the AS line-up, the 4T MK sits as the straightforward, high-value professional collector. It shares the same 53 cm deck concept and 3-in-1 capability as the higher MK B and 2-stroke slope versions. The difference is intent: the 4T MK is for daily commercial mowing with collection as the priority, not for extreme slopes or rough scrub. Contractors who need more safety features choose the MK B; those with consistent steep banking move toward the 2T models.
Optional Extras and Practical Add-Ons
- Tilt Meter: Helps operators gauge safe working angles on banks.
- Hour Meter: Useful for tracking maintenance, billing and contract reporting.
Operational Realities Worth Knowing
The AS 531 4T MK handles slopes well for a 4-stroke mower, but it is not a substitute for the 2-stroke or 4WD bank models. For most contractors, the balance of weight, traction and handling is ideal for general commercial work, but heavy banking every week will eventually expose the limits of a 4-stroke.
Collection performance stays high as long as the blade is sharp and the deck is kept clear. The mower is happiest when used at sensible ground speeds, especially in wet conditions. The 3-litre tank gives a good working window, and the Kawasaki engine’s fuel use is predictable, so operators can plan their shifts without frequent refuelling.
How Suffolk Mowers Supports Your AS 531 4T MK
When you buy the AS 531 4T MK from Suffolk Mowers, you get more than the machine itself — you get a dealer that understands the AS range and works with it daily. We set each mower up properly, confirm blade alignment, check drive engagement and make sure the controls operate cleanly before it leaves the workshop. If you’re running a mixed fleet, we’ll also advise on where the 4T MK fits within your workload compared to the MK B or 2-stroke models.
Our workshop handles all servicing, blade sharpening and repair work. The Kawasaki FJ180V KAI engine is straightforward to maintain, and we stock the filters, belts, blades and consumables needed to keep downtime low. If you’re managing a team, we can help you put together a maintenance plan and a simple checklist so operators can look after the machine without guesswork.
Parts and accessories such as tilt meters, bag replacements and service parts are either kept in stock or sourced quickly. If you’re looking to standardise across several machines, we can help you keep blades, belts and common wear parts ready to go so your team isn’t stuck waiting during peak mowing season.
AS-Motor provides up to a 2-year professional warranty when serviced through an authorised dealer, and Suffolk Mowers handles warranty claims directly. Bring the machine to us if anything develops and we’ll take care of the assessment and paperwork so you can keep your schedule moving.
Technical Specifications
| Cutting Width | 53 cm |
| Maximum Grass Height | 30 cm |
| Engine Manufacturer | Kawasaki |
| Engine Type | FJ180V KAI (4-stroke) |
| Work Rate (Max) | 3.4 kW / 4.6 hp |
| Rated Power | 2.9 kW / 4.0 hp |
| Nominal Speed | 2800 rpm |
| Fuel Tank Capacity | 3 litres |
| Drive | Rear-wheel drive |
| Number of Speeds | Variomatic |
| Maximum Speed | 4.5 km/h |
| Blade Clutch | Yes (separate blade stop) |
| Mulching Function | Standard |
| Cutting Height | 30–80 mm |
| Cutting Height Adjustment | By wheel |
| Cutting Height Levels | 6 |
| Dimensions (L × W × H) | 164 × 59 × 99 cm |
| Weight | 60 kg |
| Warranty | Up to 2-year professional warranty (dealer serviced) |
Frequently Asked Questions About AS 531 4T MK
The airflow from the Kawasaki engine and the deck design give strong bag fill, even in damp conditions. As long as the blade is sharp and ground speed is sensible, it collects cleanly across most commercial sites.
It handles banks and uneven areas well thanks to the limited-slip differential and automatic parking brake. It is not a substitute for AS’s 2-stroke slope mowers, but for typical contractor slopes it performs confidently.
Yes. The mulch kit is included and fits without tools. You can swap between bagging, mulching and rear discharge depending on grass conditions.
It’s a proven contractor engine with steady torque, reliable starts and strong performance in thicker grass. It’s easy to service and runs well on daily stop-start work.
At 60 kg it’s heavier than domestic machines, but the weight helps with stability on slopes. The Variomatic drive and handlebar design keep it manageable during long shifts.
AS-Motor offers up to a 2-year professional warranty when serviced through an authorised dealer. Suffolk Mowers handles warranty inspections and claims directly.

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