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10 of 10 Gas self-propelled · Walk-behind
PowerSmart
PowerSmart 21 in. 170cc RWD Self-Propelled (V8721S1)
The rear-wheel-drive gas mower Amazon itself stocks and ships at the bottom of the price list: 170cc, 21 in, six heights, and a review record that says buy it for a flat quarter acre and keep the receipt.
Where it sits 10 of 10 overall 02 of 2 in Gas self-propelled type median 6.5 (n 2) field median 7.3
Drawn from the spec sheet: ¼-acre reference lot (walk-behinds are not lawn-rated) · slope not rated · 21 in passes, so far fewer of them · you push it, so the rows are yours. Manufacturer ratings, not our measurements.
Amazon link · we earn a commission if you buy · $399.99 MSRP · Amazon price not shown
cut = score, 5–10 in half-point notchesuncutdry patch = weakestgas self-propelled median, n 2
Scoring note
Reliability 5.0 (30%): 3.6 stars across nearly two thousand Amazon ratings and a quarter of Walmart reviewers at one star, with starting, drive-cable, cord and wheel failures as the themes Performance 6.5 (25%): 170cc and a 21 in deck handle a flat quarter acre; not a tall-grass mower Usability 7.0 (20%): light, simple, six heights on one lever; the single-speed drive runs faster than some owners walk Value 8.0 (15%): the cheapest rear-drive gas mower Amazon stocks itself Support 6.0 (10%): Amazon handles returns, the maker handles a two-year warranty by mail, and independent shops decline the brand Weighted total 6.3 (6.325).
Recommended for
Not where
Built from 6 sources: 2 owner threads, 1 hands-on review, 3 spec pages.
We don't sell these and we don't run them. The score is the weighted result of five factors read from the sources above; specs last checked Sep 26, 2026. How the five factors are weighted →
Manufacturer ratings, not our measurements. The retailer's page is the one that counts at checkout.
SpecAmazon reviews
Amazon listing: V8721S1, 170cc OHV, RWD, 21 in, 1.4 bu, 1.5 to 3.9 in in six positions, 10 in rear wheels; sold and shipped by Amazon.com, 3.6 stars over 1,881 ratings on 2026-09-26
SpecPowersmartusa
PowerSmart product page for the V8721S: regular and sale price, 170cc, 21 in, 3-in-1
SpecPowersmartusa
PowerSmart warranty page: two-year limited warranty from the date of purchase; several retail listings advertise three years instead
Hands-onToolsofficial
Tools Official review analysis of the PowerSmart 170cc family: wheels crack or break (14 reviews), rear discharge flap fails (10), plastic parts deteriorate with heat (8); lists 66.3 lb, 1.4 bu, 1.5 to 3.9 in and a 3-year warranty claim
OwnerWalmart
Walmart reviews of the 21 in 170cc self-propelled: 3.6 stars over 3,613 ratings with 25 percent one-star; starting trouble, jumpy or too-fast self-propel, snapped pull cords, starter coil failure, belt off the drive
OwnerHome Depot reviews
Home Depot reviews of the V8721S: starter coil replaced after a few uses, self-propel motor quit, handle plastic broke at the screw mount, repair shops refuse the brand
09 of 10Gas self-propelled
The cheapest 22 in rear-wheel-drive gas mower Amazon ships, sold by the maker itself: a 170cc engine, a 16-gauge steel deck and 60 lb on the scale, with plastic wheels and a flap that owners end up replacing.
vs. the 21 in. 170cc RWDReliability +0.5Performance +0.5Usability +0.5
Not rated for this yard
Amazon link · we earn a commission if you buy · $399.99 MSRP · Amazon price not shown
08 of 10Battery push & self-propelled
It cuts like a gas mower and the rear-wheel self-propel is genuinely good, but plan on a second 4Ah battery for anything past a quarter acre and treat the plastic drive gears gently.
vs. the 21 in. 170cc RWDReliability +1.5Performance +0.5$300 more
Not rated for this yard
Amazon link · we earn a commission if you buy · $699.99 MSRP · Amazon price not shown
21 in. 170cc RWD
6.3/10 · PowerSmart