Cobra M51SPC 20″ Petrol Lawn Mower Review

Cobra M51SPC Petrol Mower Review
Cobra M51SPC
What I Like
Excellent choice of 10 cutting heights
Self-propelled single speed drive
Versatile mowing & cutting options with 4 in 1 mowing options
Great for large lawns & gardens
Ecellent build quality
Lengthy warranty
Powerful, high torque 173cc engine
What I Don't Like
No variable speed
No electric start option
My Overall Rating


Cobra M51SPC Review

The Cobra M51SPC is a self-propelled petrol mower fitted with the powerful 173cc DG600 engine and has 4-in-1 cutting options. These options include cut and collect, mulching and side & rear discharge. This mower has a 51cm cutting width, steel deck, 10 cutting heights from 25mm to 75mm and a 60 litre soft mesh, solid top grass collection bag.

When you first look at the price of the Cobra M51SPC, you could be forgiven for thinking that it’s a little over the top. But hear me out, this should be seen as an investment because this durable mower is one that will keep performing mow after mow. Not only that but it has some amazing features that make light work of keeping your garden tidy and that makes it excellent value for money.

With a range of ten cutting heights, 4 in 1 mowing and an engine that’s designed to get up and go, the Cobra M51SPC is a petrol mower that is difficult to beat. It’s also extremely convenient and easy to use with plenty of comfort features such as a soft touch handle and self-propelled drive. Cutting the grass has never felt so luxurious!

I’ve been checking out some of the best features of the Cobra M51SPC and am excited to share these with you. In my Cobra M51SPC review, I’ll cover everything you need to know to help you work out whether this is the right lawn mower for you.

Main Features

  • 51cm cutting deck
  • 4-in-1 mowing – Cut & collect – Mulching – Side & Rear Discharge
  • 10 cutting heights
  • Self-propelled drive
  • Powerful DG600 173cc engine
  • Folding handles
  • 60 litre grass collection box
  • 2 year warranty


The Cobra M51SPC is fitted with a super powerful DG600 engine that is designed with the latest technology delivers 173cc of power. It’ll make light work of whipping around larger gardens and is quiet, so you won’t disturb the peace as you work. What’s more, this high torque engine is a great little starter and when using the choke, starts easily from cold.

Click for Best Price


Cobra M51SPC Video

To get a visual representation of the Cobra M51SPC petrol lawn mower see the video below.


You’ll get a very high-quality cut from the Cobra M51SPC petrol mower and in larger gardens, you will find that the self-propelled drive makes life so much easier. No more exerting yourself to get around the entire lawn because the Cobra M51SPC does the hard work for you.

The Cobra M51SPC runs at 3.2mph which is pretty fitting with the pace at which most of us walk. However, it isn’t going to be suitable for everyone and with that in mind, Cobra have another model; the M51SPB which has a four speed gear box so allows for variable speed. This one is also kitted out with a 163cc Briggs and Stratton 650EXi Ready start engine so it’s even easier to get going.

Do keep in mind that this variable speed model, with the B & S engine, is a little heavier than the Cobra M51SPC at 41kg but with the self-propelled variable speed drive, that isn’t going to make much of a difference.

Self-Propelled Drive

This Cobra M51SPC is self-propelled making it easy to manoeuvre around the lawn. Whilst the single speed is a good walking pace, it does lack the variable speed option of its larger brother, the Cobra MX534SPH and that of the M51SPB as mentioned above.

Features In Detail

Blade And Deck

The Cobra M51SPC has a 51cm, that’s 20 inches, cutting deck which make it an excellent choice if you have a larger lawn. The engine and this cutting width combined will make light work of areas up to around 600 plus square metres.


One of the things that I love about the Cobra M51SPC is that it has a very comfortable soft grip handle. When you’re mowing a larger garden, the last thing you want is something that makes your hands feel sore but that certainly won’t be a problem here.

Moreover, all of the controls such as the choke and throttle are easily located well within reach, so you won’t need to stretch to operate the mower. Plus, when you’re finished, the Cobra M51SPC’s handle has a quick release function, folding down for easier and more convenient storage.

Height Adjustment

I could not believe my eyes when I saw that the Cobra M51SPC has a choice of ten cutting heights! Seven is usually standard so this is incredibly generous and allows for much more versatile mowing regardless of the weather, season or conditions. Cutting heights range from 25mm to 75mm.

What’s more, there aren’t any complicated processes to change the cutting height and with the help of a single lever, you’ll change the height and be cutting in a matter of seconds.

Mowing Features

If you thought that the excellent number of cutting heights was good, just wait until you learn that the Cobra M51SPC is a 4-in-1 lawn mower. This means that you get four different mowing functions for every eventuality.

There’s a side discharge and a rear discharge chute which allows you to deposit the clippings either to the side or behind as you mow. You also have a mulching plug which can be inserted into the back of the lawn mower and will cause the clippings to circulate around the deck before being sent back to the lawn to act as a fertiliser; talk about killing two birds with one stone.

Of course, you also get the traditional cut and collect option and since the Cobra M51SPC comes with a massive 60 litre grass bag, you won’t have to empty it very often. In addition, this is a fabric grass bag so the clippings will be much more compacted thanks to improved air flow.


If you spend a lot of time trying to maintain your lawn, then mulching might be an option. This method of mowing allows the clippings to be spread back across the lawn as you mow.

This delivers a wealth of nutrients and acts as an additional fertiliser – why do the two jobs separately when you can do them together?

This Cobra M51SPC comes with a mulching plug so you can mulch as often as you like.

If you would like to learn more about the benefits of mulching why not read my complete guide.

Safety Features

As with many lawn mowers, the Cobra M51SPC features a safety OPC lever. This has to be held in order for the lawn mower to start. If you’ve got kids, this lessens your concern that they will be able to accidentally start it up.


The Cobra M51SPC is a superb machine and I have no doubt that it will stand the test of time. But just to be on the safe side, you will get a two-year warranty as standard with this lawn mower so that gives you great peace of mind.

At 38kg, you might think that this is a heavy mower but when you compare it to some others in the same league, you’ll see that it’s relatively lightweight. Plus, when you consider that you’ve got the self-propelled drive, it soon becomes clear that weight really isn’t an issue.

Cobra M51SPC User Manual

Click here to access the Cobra M51SPC User Manual

What’s Included In The Box?

  • 1 x Cobra M51SPC
  • Mulching plug
  • Side discharge chute
  • 60 litre grass box
  • Engine oil
  • User manual

Pros and Cons

  • Excellent choice of 10 cutting heights

  • Self-propelled single speed drive

  • Versatile mowing & cutting options  with 4 in 1 mowing options

  • Great for large lawns & gardens

  • Excellent build quality

  • Lengthy warranty

  • Powerful, high torque engine

  • Comfortable and user friendly

  • No variable speed

  • No electric start option


Should You Buy This Cobra M51SPC?

Cobra M51SPC Conclusion

I would absolutely recommend the Cobra M51SPC to anyone who is looking for a high-quality lawn mower that will have a long service life. While it is a little expensive, it’s not all that bad for a petrol mower especially when you consider the number of features you are getting and the build quality.

I’d also say this was a great choice for people who don’t usually use a petrol lawn mower or are moving over from electric. It’s really simple to use, so easy to get to grips with and while this is the case with a lot of modern petrol mowers, there’s just something about the Cobra M51SPC that makes it ultra user friendly. Maybe it’s the comfort features, or perhaps it’s the versatility but in any case, I love it!


Cobra really have outdone themselves when it comes to the Cobra M51SPC. This is an excellent everyday lawn mower that has the features of a more professional tool. It delivers a high-quality cut in as quick time as possible and is extremely easy to use.

If it’s versatility you’re looking for then you won’t go far wrong with the Cobra M51SPC since it has 4-in-1 mowing feature and a staggering number of cutting heights. If you’re in the market for a petrol lawn mower for a large garden, this is well worth considering.

Where Should I Purchase This Cobra M51SPC?

Click for Best Price


Cobra M51SPC 20' Petrol Lawn Mower Self Propelled 4in1 Mulch Collect...
52 Reviews
Cobra M51SPC 20" Petrol Lawn Mower Self Propelled 4in1 Mulch Collect...
  • 51cm (20in) Cutting width petrol lawnmower
  • 10 Stage height of cut adjustment with a single lever control, 25mm to 75mm heights
  • Self propelled drive system for effortless mowing
  • Large 60l garss bag collector for less bag emptying
  • Powerful DG600 OHV petrol engine

Last update on 2024-07-13 / Affiliate links / Images from Amazon Product Advertising API


Not sure about this Petrol Lawn Mower? Click here for more Petrol Lawn Mower reviews.

Want to lean more about what’s involved in maintaining a petrol lawnmower? Check out my guide 10 Simple Steps to Maintaining Your Petrol Lawnmower

Mark Haley Author
Lawnmower Product Expert, Reviewer and Author at | 01284 615144 | | Website

As a seasoned expert in the field of garden power tools, I have dedicated over a decade to working with and reviewing a wide variety of lawn mowers. My extensive experience has allowed me to gain a deep understanding of the benefits and limitations of different types of mowers and garden tools.

Over the years, I have honed my skills in writing informative articles and creating helpful videos for various blogs and publications. This has given me the ability to not only recognise what makes a good lawn mower, but also to help you choose the perfect garden tool for your specific needs and requirements.

With my wealth of knowledge and expertise, I am confident that I can provide you with valuable insights and recommendations when it comes to selecting the right lawn mower for your lawn. So, whether you're looking for a battery cordless, electric, petrol, or robotic mower, you can trust in my expertise to guide you towards the best option for your garden.

Leave a Comment

Your email address will not be published. Required fields are marked *

This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply. Protection Status

As an Amazon Associate I earn from qualifying purchases. is a participant in the Amazon Services LLC Associates Program,
an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to,,
and any other website that may be affiliated with Amazon Service LLC Associates Program.

Scroll to Top