In Brief: How to Make a Lawn Mower Fast
The easiest way to make a riding lawn mower faster is to swap the large drive pulley out for a smaller pulley. For a push mower, you can increase the speed by increasing the engine RPMs. Do this by bending the governor arm to adjust the control spring tension.
Lawnmowers are notoriously slow. Whether you have a walking mower with a slow blade or a riding mower that drives at a top speed of 3 mph, a little extra speed is appreciated.
As it turns out, there are a few easy things you can do on your own to increase your mower’s speed. Learn how to make a lawn mower fast in this guide.
2 Methods to Make a Lawn Mower Fast
Because there are different types of mowers that might need speed upgrades, this guide is broken down into two parts. The first method is for riding driving speed and the second method is for push mower engine speed/self-propelled drive speed.
Method 1: Pulley Swapping
For riding lawn mowers, the simplest way to increase the speed is to do a pulley swap. The drive pulleys on a mower affect the engine speed. By changing the size of the pulley your mower is using, you can increase the top speed.
Keep in mind that while pulley adjustments might increase speed, they will decrease power at the same time. If you’re mowing on uneven terrain or very thick grass, you need to balance speed and power.
- Step 1: Identifying Pulley & Belt Sizes
Before working on your mower, remove or plug the battery to avoid accidental starting. Look at your mower to see if you can locate the pulleys from the back. If they’re not visible from the back of the mower, prop it up to look at the bottom.
The pulleys are likely to be visible and accessible from the bottom. On a riding mower, pulleys look like discs wrapped in a thick rubber belt.
When you locate the pulleys on your mower, measure them to see what size the mower is currently using. Measure the belt size as well. You may need to remove the belt to measure it.
- Step 2: Swapping Pulleys
Mowers use at least two pulleys. Generally, one pulley is significantly larger than the other. This size difference causes the mower to run at lower RPMs than it’s capable of. It’s set up this way to increase engine power.
The pulley that’s connected to the crankshaft is the drive pulley. By reducing the size of the drive pulley, increasing the size of the secondary pulley, or doing both, you can increase the speed of the mower.
You can either choose to purchase different sized pulleys or do a direct swap of the two pulleys. They easiest way is to swap the existing pulleys. This keeps you from having to purchase a different belt to accommodate the potential changes in pulley size.
To do a pulley swap, first remove the belt from the pulleys and set it aside. Then, remove both pulleys. Switch the pulleys and install them each one where the other way before, with the larger one going on the crankshaft.
Secure each pulley in place. Depending on the layout of your mower, this may require some extra work. When the pulleys are secured in place, reinstall the belt. Check that the belt isn’t blocked by anything under the mower and that it is able to spin freely.
- Step 3: Testing
Put the mower back on its wheels and reinstall the battery. Turn the mower on and test the speed with the new pulley setup to see if it’s running faster than before. If you’re not satisfied with the results, you can buy new pulleys of different sizes and install them instead.
Note: Any time you make changes, you should test the mower’s performance. Listen to engine sounds and pay attention to how well it runs after pulleys have been swapped. Lawn mower engines can be damaged by running at high RPMs for extended periods of time.
Watch a pulley swap on a riding lawn mower:
Method 2: RPM Adjustment
For a push mower, speed is also important. If you want to mow faster, you need your blade to spin more quickly or your self-propelled drive wheel move faster. You can do both of these things by adjusting the engine RPMs.
Step 1: Locating the Governor Arm
On most push mowers, the governor arm is located on the side of the mower. The governor acts as a sort of cruise control for your mower, keeping the engine running at a steady speed at all times. To find the governor arm, look around the outside of the mower or directly under the engine guard for a small metal spring.
See an example of a governor arm and spring: https://youtu.be/GT1p0GT0TI4
Step 2: Shortening Spring Tension
The governor arm holds the governor spring in place. This spring puts a specific amount of tension on the engine to maintain a specific RPM range. By adjusting the tension of the spring, you can either increase or decrease the engine speed.
Adjust the tension by bending the governor arm closer to the spring or further away from it. Bend it gently and you’ll see the spring tension changing.
Alternatively, you can search for a new governor spring with more or less tension than your current spring. Increasing the spring tension increases the RPMs while decreasing the tension reduces the RPMs.
Step 3: Measuring & Adjusting
Mower engines cannot run efficiently at all engine speeds. Check your manufacturer’s recommendations for the limits on engine RPMs for your specific model. To ensure you’re running within the limits, use an RPM measurement device to check the RPM speed after each adjustment.
If the RPMs are too high, your engine can fail. You can damage your mower by consistently operating it outside of the recommended RPM range, so adjust it carefully until the engine is running at the speed you want. Watch this method in action:
When you’re looking for a little more speed from your mower, there are a few simple ways to do it. Whether you do a pulley swap or you adjust the tension on your governor spring, it’s important to pay attention to the limits of your mower engine. Always work within the manufacturer’s suggestions.
Do you have any questions about making your lawn mower faster? Leave a comment below.