PowerSmart 21" Self-Propelled Gas Lawn Mower | 170cc OHV Engine | Rear-Wheel Drive for Slopes | 3-in-1 Bag, Mulch & Discharge | 6 Cutting Heights | Durable Steel Deck| Rear-Wheel Drive | Medium Yard

What It Is

This is a complete self-propelled gas lawn mower (model PS21S170A) from PowerSmart, designed for medium-sized yards (up to ½ acre) with slopes. The rear-wheel drive system provides extra traction on hills, and the 170cc OHV engine powers a 21-inch steel deck for cutting, bagging, mulching, or side-discharging grass.

Fitment & Compatibility

• Deck size: 21-inch cutting width – standard for residential mowers.
• Model/brand: Confirmed fit for PowerSmart PS21S170A only. Not compatible with other PowerSmart models (e.g., PS21B, PS21SP) or other brands (Honda, Toro, etc.).
• OEM vs aftermarket: This is the OEM mower – not a replacement part. If you need a wheel or tire, check the specific part number (e.g., wheel assembly PS21S170A-WH) for direct replacement.
• Measurements before buying: Verify the wheel diameter (typically 7-8 inches rear, 6-7 inches front) and axle hole size (usually 5/8 inch or 3/4 inch). Remove a wheel and measure the axle diameter and hub width to ensure match.
• Deck bolts: Ensure any wheel or hardware you buy fits the 21-inch steel deck’s bolt pattern (typically 4-bolt, 2.5-inch spacing).

Key Things to Know

• Quality: Steel deck is durable, but plastic wheel hubs can crack under heavy use on rough terrain. Check for wobble after 20+ hours.
• Installation difficulty: Replacing wheels is easy (remove cotter pin or bolt, slide off), but adjusting the self-propel drive cable may require a wrench and patience. Follow the manual for belt tension.
• Common gotchas: The rear-wheel drive system uses a single-speed transmission – not variable speed. On steep slopes, the drive may slip if tires are worn. Replace tires with OEM or aftermarket 7x1.75-6 (rear) or 6x1.50-6 (front) if needed.
• Engine compatibility: The 170cc OHV engine uses standard SAE 30 oil (not synthetic) and a standard 3/4-inch spark plug (Champion RJ19LM). Aftermarket air filters (e.g., for Briggs & Stratton 500e) may not seal properly – stick with PowerSmart part PS21S170A-AF.

Should You Buy It

If you have a medium-sized, sloped lawn and need a budget-friendly self-propelled mower, this is a solid pick – the rear-wheel drive helps on hills, and the 3-in-1 system adds versatility. But if you need variable speed, a larger cutting deck, or heavy-duty wheels for bumpy terrain, look elsewhere. For basic residential use on gentle slopes, it’s worth the price.