If you want a reliable mower all season, who doesn’t? Then your Riding mower will need a tune-up at least once a year, preferably in the spring before the season starts. If you want a reliable mower all season, then your Riding mower will need a tune-up at least once a year, preferably in the spring before the season starts.
So what is riding mower maintenance? To maintain a riding mower, the following components need attention:
- Full mower inspection
- Oil & filter change
- Air filter change
- Fuel filter change
- Spark plug change
- Axle lube
- Blade sharpen
- Tires pumped
- Deck align
- Throttle cable adjusted
At the very minimum, the oil should be changed at the start of the season. If your mower is new, change the oil after the first 5 hours of use. Some mowers will have a useful tune-up interval chart stuck under the hood or under the seat.
Topping Up Oil
Checking and topping up the oil is good practice, but it’s not a substitute for an oil change. If your mower has an oil filter, change it when changing the oil, this is where all the contaminants are trapped.
Info Sticker – Helpful charts are fitted to some mowers showing intervals and part numbers; however, I’ve found the Husqvarna belt labeling to be wrong; just saying!
About Your Gas Engine
The 4-stroke single and v twin cylinder engines offered by B&S, Kohler, Kawasaki, and Honda are all top-drawer, and quality parts are easy to find. Your engine may be different from the demo models used in this guide unless it’s a diesel; they’re all much similar. (see diesel engines below)
All tractor-mower engines are very durable, failures, in my experience, are rare, and when they happen, it’s usually associated with poor or low oil. That’s why checking your oil regularly and oil changes are so important.
When To Tune-up Your Gas Engine?
When should I service? I advise my customers to service their mowers at the start of the season, not at the end. Mowers that overwinter without being prepared usually suffer from gummed carburetor issues. You can avoid gumming by adding a gas stabilizer to the fuel system.
What Is Gas Stabilizer?
Gumming of small engine carburetors is a real problem. Over the winter months, the old gas eats away at the inside of the carburetor. This is so common, and it’s so simple to prevent. Use a gas stabilizer at the season’s end; dump a few drops into a full tank of gas, and run the engine for a short while. See the video here about mixing and adding gas stabilizers.
If your mower is running rough, changing the oil, plugs, air, and fuel filter may not fix it. Gas mowers that run rough usually require carburetor cleaning. Check out “Carburetor troubleshooting.”
What Tools Are Needed?
A tune-up isn’t technical, and no special tools are needed. Like many tasks, it’s about the right knowledge and good preparation.
When it comes to tools, you don’t need top of a line kit but do buy good quality tools because good tools, well cared for, will last a lifetime.
- 1/4 & 3/8 Drive Socket Set
- Selection of Wrenches
- Selection of Screwdrivers
- Torx Drivers
- Flat File
- Wire Brush
- Oil Catch
- Oil filter tool
- Air Pump
- Inspection Light
- Grease gun
What Tune-up Parts Needed?
All engines have a model code and date stamped somewhere. Briggs & Stratton stamp their codes into the metal valve cover at the front of the engine. Kohler has a tag, and Honda has a sticker on the body.
Tune-Up Kits – Tune-up kits will include plug(s); oil; oil filter (if fitted); air filter; fuel filter – everything you need.
If you’re having trouble identifying your engine type, you can usually identify the right tune-up kit by the shape of the air filter.
Check out your engine maker specs:
- Briggs and Stratton tractor mower engines
- Honda specification
- Kohler specification
- Kawasaki specification
Inspection & Tune-up
In this guide, we will tune up a single-cylinder engine. In addition to a tune-up, doing an overall visual inspection is good practice. Mowers create a lot of vibration, so look for any loose or damaged components, check rear axle oil, belts, pulleys, deck spindles, deck arms, battery connections, cables, etc. Finding problems now is usually cheaper than them finding you later.
Your mower may not be the same as the demo model, but that’s not important; the process will be close to identical no matter what model you have.
There are many different makes of mowers, and many are fitted with the very reliable Briggs & Stratton single-cylinder engine. Kohler, Kawasaki, and Honda are also quite popular engines. All these engines are simple and easy to work on.
Tune-up Stepped Process
We’ll begin the tune-up process by starting and running the engine for a while, just long enough to warm the engine oil. Warm oil flows more freely, which helps remove more contaminants from the engine.
1 Wire – Remove the plug wire and leave it off until you are ready to start the engine later in the process.
2 Plug – Remove the old spark plug. To avoid cross-threading, thread the new plug in by hand before using the plug tool.
Snug the plug down and give it a little tighten…. not too tight! Don’t fit the plug wire just yet.
3 Drain – Drain the oil while the engine is still warm; this helps the draining process.
4 Remove – If you can’t find your oil filter, then you don’t have one, so you can go ahead and skip this part.
Remove the old filter, you may need an oil filter tool, but they’re usually not that tight.
5 Fit Filter – When fitting the new filter, apply some oil to the O-ring; it prevents distorting the seal when fitting. Only tighten the filter – hand tight.
6 Add Oil – If your mower has an oil filter, then check the oil level again after your test run of the engine. This can be done at the end of the tune-up.
7 Check Levels – Add oil a little at a time, and check the level. Overfilling is not good for the engine. It will cause oil leaks, misfiring, and lots of smoke.
8 Check – Check the rear axle oil level. The front Axle has greasing points; for this, you’ll need a grease gun.
9 Air – Remove the air filter and clean the airbox being careful not to allow dirt into the carburetor. Refit the new filter or clean the old filter, by tapping it on a hard surface or better-compressed air, but never wash a paper filter.
10 Remove – Gas filters are found on the gas line between the gas tank and the carburetor. If you have a gas tap fitted, it’s useful to turn it off before removing the old filter.
Gas filters may be directional, and if so will have an arrow that points to the carburetor.
11 Clean – Gas tank grit is common, I use a suction bottle and tube to remove it, and sometimes I have to remove the tank to clean it.
12 Jack – Be sure to use an axle stand or block of wood to secure the mower, as you’ll be working under it.
Don’t take any chances. Check out the tools on the blade maintenance page.
Deck – If you are not comfortable working under your mower, then remove the deck. Most decks will be pretty simple to remove.
Balance – Removing deck blades for sharpening and balancing is the best practice. Inspect the blades for damage, and replace them if bent, cracked, or worn. If the blades are in good condition, you can sharpen them in place.
13 Sharpen – Sharpening your blade is done with a good quality flat metal file.
Flat – Begin by dressing the face of the blade to remove any small nicks.
Bevel – Now we will file at the same angle as the bevel; some blades will have the bevel facing the other way.
Dress – Now dress on the opposite side to remove the burrs. A sharp blade is the secret to a beautiful, healthy lawn, and it extends the life of your mower.
14 Check – Check the condition of the belts. Most mowers have at least two belts, one for driving the mower and one for driving the blades. Some mowers will have more.
Flat Spot – These belts have a difficult job and can be the cause of various issues. Regular inspection will tell you if your belt is at the end of its life.
Blistering – Things to look for are flat-spotting, glazing, cracking, and fraying.
Glazing – Worn or damaged belts cause slip, which in turn will cause vibration. The vibration can, if ignored, go on to cause lots of other issues.
Cracking – Better to take care of this now; waiting for it to break can cause other damage.
15 Pump – Check tire pressure and set it to 1bar/15psi. Some customers like a lower pressure, and that’s okay; what’s important is that they’re all the same.
16 Level – Decks tend to drop at the front over time. Place the mower on level ground.
Measure the height of the four corners of your cutting deck.
Measure – Let your deck down approx. halfway. Now measure the height of the four corners of your cutting deck.
Note the highest corner, and adjust all other corners up, so they match.
Adjust – You’ll find adjusters at each corner; they’ll have a lock nut that will need to be released first.
Turning these bolts adjusts the deck up and down. Spray with WD40 – makes life a little easier.
Clean Cut – Decks that sag will impact your lawn, causing damage to your blades and your lawn. Keep your deck level and blades sharp; you’ll be rewarded with a healthy lawn and a healthy mower.
Diesel Engine Difference
Some manufacturers offer small diesel engines in their mowers; the main advantages are fuel efficiency and lots of torque. Mostly they’re fitted to the commercial range. Diesel engines tend to be very reliable. However, they cost a lot more than a gas engine to repair when they fail.
Service to a diesel engine will include oil; oil filter; fuel filter; air filter. Doing an oil and filter change is just as important on a diesel. Note, if you’re changing a fuel filter on a diesel engine, the air must be purged from the system before starting the engine.
Purging Diesel Fuel System
Fill the new filter with fresh diesel before fitting. Then pump the primer, if installed on the machine. If you don’t have a primer – open the fuel lines at the injectors by about two turns, and now crank over the engine until fuel spills from the fuel lines. Tighten up the lines, and your good to go. If your diesel still doesn’t start after purging, it must be purged again.
Should I run my lawnmower out of gas for winter? Using a gas stabilizer is better than running a mower out of gas. The stabilizer will keep gas fresh and protect the fuel system over the winter months. Running the gas out of the mower doesn’t prevent gumming of the carburetor.
Can you store a lawnmower vertically? A lawnmower should be stored on its wheels; however, if you drain the oil and gas from the engine you can store it in any position you like.
About the Author
John Cunningham is a Red Seal Qualified automotive technician with over twenty-five years experience working on all types of equipment, grass machinery, ATVs, Dirt bikes, cars, and trucks. When not writing how-to articles, he may be found in his happy place – Restoring classic machinery.
You may find the following links helpful:
- Riding mower maintenance & repair index
- Walk behind mower maintenance & repair index
- Recommended tools & parts
- Recommended mowers
- Repair videos
- About the Author
- Latest Posts
John Cunningham is an Automotive Technician and writer at Lawnmowerfixed.com.
He’s been a mechanic for over twenty-five years and shares his know-how and hands-on experience in our DIY repair guides.
Johns’s fluff-free How-to guides help homeowners fix lawnmowers, tractor mowers, chainsaws, leaf blowers, power washers, generators, snow blowers, and more.