This video walks you through the diagnosis & repair process step by step, including checking the oil level and removing excessive oil the easy way, checking compression, fitting a new carburetor. Before working on your mower be sure to remove the plug wire to prevent accidental starting, see “Repair Safety Video”.
You’ll find useful resources on this page, tips, links to tools, parts, and supplies required to complete your repair. White smoke is the drama queen of mower problems, sure it looks bad, but it rarely is. The smoke is caused by oil mixing with gas in the combustion chamber. As the oil burns, it bellows white smoke.
Excessive oil in the cylinder is usually caused by:
- Tilting mower wrong way
- Overfilling oil
- Faulty carburetor float needle
- Blown head gasket
- Engine rings worn
Briggs & Stratton – Most models take from empty .65 US quarts (.6 lt) 5W30 engine oil.
Honda engines – Most take from empty .58 US quarts (.55 lt) of 10W30 engine oil.
Kawasaki engines – Most take from empty .6 US quarts (.6 lt) 10W30 engine oil.
Kohler engines – Most take from empty .6 US quarts (.6 lt) 10W30 engine oil.
For exact specs see:
Tools & Parts
This is first on the list for good reason, WD solves a ton of problems. I won’t work without it, because I can’t. Picture links to Amazon.com.
Ratchet Tool Set
Before we can do anything, we’ll need tools. I’ve selected this set as I own some Craftsman tools and while I have worn some out, they did do a lot of work. So I expect this set will last the occasional user quite a long time. This set carries both metric and standard sockets and that’s important because some mowers will have both types of fastener sizes. Set includes spark plug sockets. Picture links to Amazon.com.
Gas & Oil Syphon
You’ll find this tool really useful if you need to drain the gas tank, and you will if the gas is stale. The siphon will remove it without fuss or mess and it can be used for extracting the oil too. Picture links to Amazon.com.
Gas Line Clamp
Some small engines will have a gas tap, which is really handy when removing the carburetor, stops gas flowing all over the shop. However most engines won’t have one, these useful clamps simply squeeze the fuel line and prevent a spill while you perform surgery. Picture links to Amazon.com.
When cleaning your carburetor you’ll need this stuff. Gumming is a sticky substance that’s hard to shift. The carb cleaner will remove it, however, if your carb is really bad, save yourself some work, go ahead and buy a new carburetor. Picture links to Amazon.com.
You’ll find these nylon brushes super useful when it comes time to clean those tiny passageways of the carburetor and jet. Use these in conjunction with the WD Carb cleaner. Picture links to Amazon.com.
Mix this with the gas when winterizing your small engine. Gas isn’t what it used to be, it goes stale, in some cases after just one month. Bad gas causes gumming and that’s a carburetor killer. A stabilizer will save you money and stress in the long run. Picture links to Amazon.com.
Briggs and Stratton refuel can. These guys got it right, I like it a lot, it offers press button control, no fuss no mess and no funnel required. Picture links to Amazon.com.
This is a compression tester, it’s fitted in the plug hole using the adaptor. The gauge measures and captures the reading on the dial. A low reading can be caused by a simple fault such as a sticking valve. Picture links to Amazon.com.
The OTc is a quality kit and will last many years of use. A leak-down tester will require compressed air. The tester measures how much air escapes a cylinder and helps you find weak rings, valves head gaskets, etc. Picture links to Amazon.com.
Briggs & Stratton
This is a popular Hooai Carburetor fitted to walk behind mowers with Quantum engines, but check the engine codes listed. This is an Auto choke carburetor. This carburetor has a fuel feed bolt in the base of the bowl, dirt in the bolt feed hole is a common issue. Picture links to Amazon.com.
Briggs & Stratton
This is an after-market replacement carburetor for the Briggs 4-7hp engines. This is the primer bulb-style carburetor. This carburetor has a fuel feed bolt in the base of the bowl, dirt in the bolt feed hole is a common issue. It comes with a replacement air filter/primer bulb housing gasket. Without this gasket, your primer bulb won’t work. Picture links to Amazon.com.
Briggs & Stratton
This is an original Briggs carburetor fitted to walk behind mowers. Part # 593261, these guys are made from plastic and I see lots of issues with them. The jet holes are particularly tiny and block so easily. There are a few different types and all look alike, so use part numbers to check before ordering. Picture links to Amazon.com.
Briggs & Stratton
This is a popular carburetor fitted to the classic range of Briggs and Stratton engines. This engine is fitted to many different walk-behind lawn mower models like MTD, TORO, Murray, Poulan, Craftsman, and many more. Picture links to Amazon.com.
Honda GCV 160
This is a Hooai carburetor fitted to the Honda GCV160 engine only, not the GVC190. It comes with gaskets, plugs, filters, and a fuel line. Fitting isn’t difficult, just a little tedious, take your time and some pictures of where the old gaskets are positioned and their orientation. Picture links to Amazon.com.
Honda GCV 190
This is a Hipa GCV 190 carburetor fitted to the Honda GCV190 engine only, not the GVC160. It comes with gaskets, plugs, filters, and a fuel line. Fitting isn’t difficult, just a little tedious, take your time and some pictures of where the old gaskets are positioned and their orientation. Picture links to Amazon.com.
- About the Author
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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.