When it comes to keeping your lawn mower running at peak performance, choosing the right vertical shaft lawn mower engine is essential.
Whether you’re replacing a worn-out motor or upgrading for better power and efficiency, the right engine can make all the difference in cutting quality, reliability, and longevity.
In this review, we highlight the 3 best vertical shaft lawn mower engines that deliver exceptional performance for various mowing needs, from heavy-duty riding mowers to compact push mowers.
We’ll explore top picks from trusted brands like Kawasaki, Briggs & Stratton, and Aceup Energy, breaking down their features, pros, and cons to help you choose the perfect replacement engine for your lawn care equipment.
1. Kawasaki 24hp Vertical 1″x3-5/32″ Shaft, Fuel Pump, Electric Start, Kawasaki Engine
This 24hp Kawasaki 726cc OHV V-Twin Engine features a 1″ x 3-5/32″ shaft, electric start, and fuel pump. A common replacement for consumer riding mowers and z-turns, it weighs 95 pounds, is made of durable aluminum, and meets original equipment specifications.
Best for: Replacing engines in consumer riding mowers and z-turns.
Pros:
- Robust 24hp Kawasaki 726cc OHV V-Twin Engine with 1″ x 3-5/32″ shaft, electric start, and fuel pump.
- A common replacement engine for consumer riding mowers and z-turns.
- Made of durable aluminum and meets original equipment (OE) specifications.
- Highly rated by customers with 4.7 out of 5 stars based on 15 global ratings.
- Positive reviews mention excellent performance, perfect fit, great packaging, and fast shipping.
- Includes a 30-day refund/replacement policy and is protected by Amazon’s A-to-z Guarantee.
- Potential $80 instant discount with the Amazon Store Card.
- Kawasaki is a highly rated brand with low returns and high order volume.
Cons:
- Limited stock available (only 9 units remaining).
- Some chosen enhancements may not be available for the current seller.
- Technical issues may occur when adding to “Wish Lists”.
- No image available for color option.
- Return policy may result in partial or no refund for used, damaged, or materially different returns.
- Requires precise measurement of your old engine crankshaft for compatibility.
- Delivery dates vary, with free delivery estimated between August 12-18.
2. Briggs & Stratton 9P602-0139 5tp 140cc Vertical Shaft
The Briggs & Stratton 9P602-0139 is a 140cc 5tp vertical shaft gas-powered engine featuring a 7/8 x 3-5/32 inch keyed crankshaft and a flywheel brake system. This black, manual-operation engine weighs 20.6 pounds and measures 16″D x 16″W x 16″H.
It is best suited as a replacement engine exclusively for push lawn mowers.
Pros:
- Runs and works great, with satisfied customers reporting good engine performance.
- Generally easy to install and connect.
- Often starts right up and can be smoother, quieter, and less smokey than replaced engines.
- Considered a good fit and can work “out of the box” for many applications.
- A great replacement engine with good quality.
- Sold at a price of $199.95.
- As a Briggs & Stratton product, it comes from a highly rated brand with low returns.
- Parts may be available for future needs.
Cons:
- Mounting holes are not threaded/tapped, often requiring additional steps or hardware like nuts and bolts.
- Some users report start-up issues, with the engine not running or starting at all.
- May not include oil, documentation, or manuals upon purchase.
- Features a flywheel brake system primarily for push mowers, which may require modification for other uses.
- The item is non-returnable due to hazardous materials regulations, unless it arrives damaged or defective.
- Will not work for other applications like pressure washers, log splitters, or edgers.
- May require drilling new mounting holes for older mower decks.
3. Aceup Energy Gas Engine Vertical Shaft
The Aceup Energy Gas Engine is a 4.4HP 173cc 4-Stroke OHV motor with a vertical shaft and primer, designed for lawn mowers and EPA compliant.
It features a 7/8″ shaft diameter and a 0.9-gallon fuel tank. Built with durable components like metal cams and forged crankshafts, it offers superior performance and a 1-year limited warranty.
Best for: Replacing old lawn mower engines and powering other light to moderate-use outdoor equipment.
Pros:
- Strong engine performance and power.
- Good fit for various lawn mower decks and parts.
- Runs quietly and smoothly.
- Easy to install and hook up.
- Often starts on the first pull when cool.
- Durable construction with quality components.
- EPA compliant.
- Cost-effective alternative to a new mower.
Cons:
- Instructions are worthless or not for the specific model.
- Can be hard to start when hot.
- Lacks throttle/speed control and runs at a constant speed.
- No oil drain plug on some units.
- Does not include oil.
- No charging system.
- Warranty support may be poor.
- Can be louder than expected.
- May require additional blade adapter and blade.
- Potential issues with fuel tank mount or air filter staying tight.
- One customer reported it was “not safe”.