550ex Series™

5.50 Gross Torque

Performance and value in one unbeatable package. You’ll love the smooth handling of the lightweight, yet powerful 550ex Series™ lawn mower engine. With a best-in-class torque-to-weight ratio, reduced vibration and quieter operation, you can give your lawn a class-A cut with ease. 550ex push mower engines come standard with Super Lo-Tone™ muffler and hassle-free ReadyStart® starting system.

  • See how easy engine starting can be. No prime, no choke–just pull for power.

  • Avoid Lawn Mower Engine Damage

    Look Before you pump fuel into your lawn mower and help avoid engine damage. Do not use any fuel containing greater than 10 percent ethanol (E10) in the engine on your outdoor power equipment.

  • Lawn Mower Engine Torque

    Cubic centimeters (cc) only measure the size of the engine on your lawn mower or outdoor power equipment. Torque measures the power that rotates the blade. Maximize your mowing power.

  • Tool-less Air Cleaner Cover

    Easy access for filter changes

  • Have a question? Search our FAQs to find answers related to model specifications, routine maintenance, repair or troubleshooting. Search FAQs »

  • Find genuine Briggs & Stratton repair and/or maintenance parts for your engine or outdoor power equipment to ensure future performance. Purchase Parts »

Torque* 5.5
Engine Displacement (cc) 140
Number of Cylinders Single
Engine Configuration Vertical Shaft
Engine Technology OHV
Length (in) 13.8
Width (in) 12.2
Height (in) 9.6
Weight (lbs) 17
Bore (in) 2.5
Stroke (in) 1.75
Engine Fuel Gasoline
Fuel Tank Capacity (gallons) 0.2
Lubrication System Dura-Lube Splash Lubrication
Oil Capacity (oz) 15
Oil Filter No
Starter Recoil
Air Filter Oil Foam or Dual-Sealing Round Paper
Muffler Lo-Tone™ or Super Lo-Tone™
Fuel Shutoff Valve No
Certified Power Rating

*All power levels are stated gross horsepower at 3600 rpm per SAE J1940 as rated by Briggs & Stratton.

*All power levels are stated gross torque at 2600 rpm per SAE J1940 as rated by Briggs & Stratton.

550ex Series™ is rated 1.963 out of 5 by 54.
Rated 3 out of 5 by from Correction of previous post I really don't like to admit I was wrong, but my discovery may explain at least some of the complaints I have seen posted for this engine. Yesterday, I posted a complaint about gasoline spewing from the carburetor, less than two months after purchase and after no more than 4 or 5 uses. Today, I called our local B&S service center and was advised that this is likely caused by water from the fuel clogging the carburetor needle. The ethanol in present day gasoline absorbs water into the fuel, rendering the fuel unreliable in less than a month. They recommended buying an ethanol treatment to stabilize the fuel, specifically suggesting either SeaFoam or Mechanic in a bottle. I purchased a bottle of the SeaFoam fuel treatment, poured a little gas in the tank, mixed in a tbsp or so of the SeaFoam, and started cranking the engine. It eventually started with a cloud of smoke, and ran perfectly. And no more gas pouring out of the carb. I mowed the front yard smoothly, and put it back in the garage. I checked an hour or so later, no gas leaking out, and was able to restart the engine, although it took several pulls and a very slow run for 20 second before it ran smoothly. I am still reserving judgement on this product before I can recommend it.Suggestion to B&S: Although you may recommended using fresh gas, few people take the time to get a new supply of gas each time they mow. Although you suggest using a gas stabilizer in your product manual and on the tag on the gas tank, you really need to make it clear that a stabilizer must be used, and what happens if you don't. It would
Date published: 2012-07-05
Rated 2 out of 5 by from does not restart after running a short time This engine has power once going. But Had this for 2 weeks and noticed gas dripping out from under carb. Motor mounted on Troy-Built walk behind mower. Anyways, bought from Lowes who is useless. Don't buy any lawn mower from them as service is last on their list of priorities. Took off air cleaner filter and notice gas coming out of bottom of two tubes on engine. Called B&S and no response 2 weeks after calling. Shame, looks like stuck float in carb and will have to rebuild and only 2 weeks old on motor. Buy Kohler engine based products.
Date published: 2012-05-15
Rated 2 out of 5 by from won't stay running Bought brand new on Troy Bilt mower at Lowes. Easy mower to assemble, added the oil supplied with engine and fresh new gas. Started on second pull. Cut front with no problem and half way through back yard it dies as if out of gas. Still had half a tank of gas and full of oil. Would start and run for about 2 seconds and die. Let cool off for about half an hour while I trimmed and then tried again. Started first pull ONLY to spit and sputter and never reach full RPM and die afterbout 1 minute. Then back to the 2 second run and die routine. I exchanged for a new one that day. I have my fingers crossed on this one that I can finish mowing my lawn today!!
Date published: 2012-05-02
Rated 1 out of 5 by from Bad Engine Bought a push mower that had this engine. Started easily as promised the first time. From day one it never ran smoothly and would rev up and down anytime it was running, but it still cut the grass so I dealt with it. I have a small yard and very little grass in the yard. I would guess I used the mower 5 times last season (definitely no more than 10) and then stored it over the winter. The following season it would not start no matter what I did. Tried new spark plug and clean air filter (although I could tell just by looking that neither of these was the problem). Got some of the spray start designed to be sprayed into the carburetor and that would allow it to start for about 2 seconds and it would die again. I had just put new fuel in it but still tried emptying that fuel out and replacing it with the same fuel but with an ethanol treatment added. Still not able to start at all. Only option presented to me is to send it for repair and not get it back for two weeks. After the very limited use this lawn mower had in its first season, there is absolutely no reason it shouldn't be able to start. Very disappointed in Briggs and Stratton and the store I bought it from after being assured that I was buying a mower with a quality engine. After this experience I have very little confidence in Briggs and Stratton engines and personally can't see myself purchasing anything with one on it again. To further my disappointment, I look on here and see all the reviews, many of which are similar to mine, and wonder to myself, why hasn't anything been done in the manufacturing process to correct these issues? Seems to me so long as people are buying them Briggs and Stratton see's no reason to improve their product. Very disappointed puts it lightly.
Date published: 2014-05-17
Rated 1 out of 5 by from Spontaneously leaking carburetor I am echoing the experience of "Angry" from Washington. Bought a Troy-Bilt mulching mower from Lowe's, and it worked great, easy start without priming, nice clean mowing about 4 or 5 times. Then about a week ago, a day after mowing, the garage had an intense gasoline fume smell. I checked all over and found no overturned gas containers, saw nothing around the mower, and the smell dissipated. Today, went out to start the mower, found the tank empty, filled it up and started to crank, but could not start it. Then I noticed a rapidly expanding puddle of gas, which was literally pouring out of the carburetor housing. Took off the air filter and filter housing, and gas was pouring out of the air inlet and actually from one of the holes that mounts the filter housing to the carb. Tried tightening the two screws covering the diaphragm, with no effect on the leakage. There was no evidence of a crack or damage on the outside of the carb housing. Contacted Lowes, which of course disavowed all knowledge of the mower since it had been off their lot for >30 days, and they do not carry replacement carbs. Went to B&S website, where I discovered that this engine has 10 negative reviews with only one positive, and that 1 of the 10 described exactly my problem.I have used mowers with B&S engines all my life, and have never had problems with them. They were usually still running when the mower housing was falling apart. However, it seems quite clear from the few reviews on this website that this company has significantly dropped its quality control.I decided to write this review not only to warn off unsuspecting buyers expecting a reliable product, but in hopes that the company might actually go back and improve their production standards for their products. If not, I am sure the many competing small engine manufacturers will be happy to take their business. Caveat emptor. I only wish I had done a little more reading of online reviews before I assumed I was buying a dependable B&S product.
Date published: 2012-07-04
Rated 1 out of 5 by from Piece of Trash. Don't waste your time on this mower Underpowered engine and a bag that only fills about 25% of the way. A horrible lawnmower. Avoid this and other Yard Machines products.
Date published: 2012-06-09
Rated 1 out of 5 by from Starts on 2 pulls, engine dies within seconds Purchased from Lowes 3 months ago. Used 5 times -- 10 hours. Now engine starts and immediately dies. Oil ok, gas ok, air filter ok. Very disappointed in this purchase. Now have to find who services a BS small engine in this area.
Date published: 2012-07-04
Rated 1 out of 5 by from Worthless Engine Worthless EngineI purchased a mower with this engine in July, it worked great for a total of 5 hours of mowing (cut the small yard 4 times) Then it just stopped running, would not start, I pulled on the starter until I was physically worn out. Pulled plug, cleaned it, pulled air filter, cleaned it, drained the fuel cleaned out the fuel tank and lines, ensured that spark plug was firing. NOTHING! This mower is less than one year old and has less than 6 house of operational time on it. I remember when B&S was considered the very best engine you could have. I no longer feel this way. It is a shame the government can't force them to recall these engines.
Date published: 2014-05-26
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