DeWalt 21 in. 163cc Rear-Wheel Drive Self-Propelled Walk-Behind Lawn Mower

Why I chose this mower

I picked up the DeWalt 21-inch self-propelled mower because, on paper, it checks a lot of boxes: a 163cc Briggs & Stratton ReadyStart engine, rear-wheel drive with variable speed, a 21-inch steel deck, and full 3-in-1 cutting capability. My yard isn’t exotic—mixed cool-season grass, a few modest slopes, some bumpy edges around beds—and I wanted something that could bag spring growth, mulch through the summer, and side-discharge when the grass gets away from me. After a full season of use, here’s how it actually stacked up.

Setup and first start

Out of the box, setup was quick. The handles swing up, the dual-lever height adjusters are intuitive, and the ReadyStart engine lived up to its name: it fired on the first pull after adding the provided oil and filling the small 0.25-gallon tank. That small fuel tank is worth noting—you’re looking at roughly 30–45 minutes of run time under load, so larger lots will likely require a mid-mow refill.

Controls and ergonomics

The rear-wheel drive system provides steady, predictable pulling power. The dual-lever variable-speed control gives you fine adjustment, though the control layout takes a mow or two to feel natural if you’re used to a single speed dial. Engagement is smooth and there’s no lurch at startup. On flat ground, pace control is excellent; on slopes, the rear drive really helps keep the front end planted so you’re not wrestling the mower uphill.

The handle geometry suits a wide range of heights. Vibration is present but not fatiguing for a gas unit in this class, and noise is typical of a 163cc mower—hearing protection is wise.

Cut quality

With a sharp blade and dry grass, cut quality is very good. The 21-inch, 15-gauge steel deck creates solid lift, giving a clean, even finish across the 1.25 to 3.75-inch height range. I found 3 to 3.5 inches to be the sweet spot for most conditions. If you’re a “mow tall” purist who likes 4 inches or higher, the max height may feel a touch conservative, but for most cool-season turf the range works.

Stragglers were minimal at proper blade height, and the deck edge gets reasonably close to obstacles. The single blade is easy to sharpen or swap, and the underside deck design cleans up without too much fuss.

Bagging, mulching, and side discharge

This is where the experience diverged.

• Mulching: With the plug installed and the deck set at 3 to 3.5 inches, mulching performance is strong. It recycles clippings finely if you avoid wet grass and don’t try to take too much off in one pass. In thick spring growth, I sometimes did a quick high pass, then dropped to final height to keep the engine from lugging.

• Side discharge: The chute moves a good volume of clippings without clogging, provided the grass isn’t wet. It’s a helpful middle ground when the lawn gets ahead of you.

• Bagging: Capacity is ample at 2.3 bushels, and airflow is good when the bag is new and clean. However, the bag retention hardware is the weak link. On turns and bumps, the bag would sometimes pop off its pins. It’s not every pass, but frequent enough to interrupt workflow. Separately, the rear flap’s hinge pin worked itself sideways over time; if it migrates far enough, the flap drops and you lose the sealing pressure that keeps clippings headed into the bag. I ended up adding small external retainers to the hinge pin and being deliberate with turns to limit side loading on the bag frame. Both mitigations helped, but this is an area that needs sturdier parts or deeper engagement.

If bagging is your primary mowing mode, this is the main factor to consider. If you mostly mulch and only bag occasionally, you’ll be less affected.

Power and engine behavior

The Briggs & Stratton 163cc ReadyStart engine has enough torque for a 21-inch deck. Under typical loads it maintains RPM well, and hot restarts are quick. On steeper sections or in heavy, wet growth, I could force a bog if I tried to cut more than about a third of the blade at a low setting. That’s normal for this size class; taking a partial-width pass or raising the deck a notch cures it.

Reliability over the season was mixed. Early runs were trouble-free, but I did have a couple of instances where the engine sputtered and quit after being parked nose-up on a slope while I moved debris. It restarted, but it’s sensitive to fuel flow and carburetion like many small engines. Ethanol-free fuel and a stabilizer improved consistency for me. If you store fuel or mow infrequently, keeping the carburetor clean and the fuel fresh matters a lot with modern small-engine designs.

Maneuverability and traction

At roughly the weight you’d expect for a steel-deck, self-propelled unit, it’s not feather-light. The 11-inch rear wheels and rear drive make a real difference over uneven ground, and traction is surefooted in dry conditions. The wheelbase feels stable on moderate slopes. Tight turning is where you feel the weight—pivoting on the rear wheels can jostle the bag assembly (again, the bagging hardware is the bottleneck). For delicate areas, I often disabled the drive and pushed to avoid jolts.

Height adjustment and deck durability

The dual-lever height adjustment is a nice middle ground between the simplicity of a single lever and the precision of four independent levers. It’s fast and consistent. The downside is that the adjustment mechanism relies on plastic components and detents. Over time, I noticed a slightly looser feel at the rear wheels when running at the highest setting, and I had to double-check the engagement after bouncing over ruts.

The 15-gauge steel deck is robust, but the underside paint wore quickly in abrasive conditions. That’s not unique to this mower, but it’s worth rinsing, drying, and occasionally treating the underside with a rust inhibitor if you mow sandy soil or pick up debris. Keep the discharge channel clean to avoid clogs, particularly when bagging.

Maintenance notes

• Fuel: The small tank encourages more frequent fresh fills—good for the carb. Consider ethanol-free fuel and a stabilizer.
• Blade: Sharpen often if mulching; this mower rewards a sharp edge.
• Drive cables: The self-propel cable stretch was minimal. Adjustments are straightforward at the handle if needed.
• Air filter and plug: Easy access; keep the filter clean if you bag dusty leaves or mow drought-stressed turf.

The mower carries a 3-year limited warranty. In practice, finding a convenient service location took some calling around. Not every small-engine shop in my area handled this particular model, so plan ahead if warranty support is a priority.

What it’s best at

• Mulching and general weekly maintenance cuts on small to mid-size yards.
• Handling moderate slopes thanks to rear-wheel drive and high rear wheels.
• Users who prefer a steel deck for durability and don’t mind routine upkeep.

Where it falls short

• Frequent bagging, especially on lumpy lawns, due to bag retention and rear flap hinge design.
• Long, continuous mowing sessions; the 0.25-gallon tank means more refills.
• Owners who need a truly “set and forget” height adjustment at max deck height.
• Wet or overly aggressive cuts; like most 21-inch gas mowers, it prefers dry grass and reasonable bite per pass.

Practical tips if you own it

• If you bag: Make your turns wide and smooth, avoid lifting the front end abruptly, and inspect the bag pins and hinge pin for movement. Adding non-permanent retainers to the hinge pin can prevent drift.
• If you mulch: Keep the blade sharp and the deck clean. Raise height a notch for thick growth and do a second finishing pass.
• For slopes: Let the rear drive do the work; don’t overmuscle the front wheels, which can jolt the bag mount.
• Storage: Clean and dry the deck underside and consider a light protective coating to ward off rust.

Recommendation

I can’t broadly recommend the DeWalt 21-inch self-propelled mower. It delivers solid cut quality, a genuinely helpful rear-wheel drive system, and easy starting, but the bagging hardware undermines the day-to-day experience if you collect clippings regularly. Add in quick-wearing paint under the deck and plastic-heavy adjustment components that feel vulnerable over time, and the value proposition gets harder to justify. If you primarily mulch on a smaller yard and value rear-wheel traction, it can do the job with care and a few owner tweaks. If bagging is a must or you want a more set-it-and-forget-it experience, I’d look for a mower with sturdier bag mounts, a more secure rear flap hinge, and more robust height adjusters.