The Stihl RL 540 Scarifier is kitted out with a Kohler HD series engine featuring cast-iron liners, and the uber-important Kohler tech that makes these engines top-of-the-line.
The Kohler HD675 Engine
This is a 2.2kw engine with an output of 2,800 rpm and being the HD Series by Kohler, it boasts a 2x longer lifespan than pervious models.
In comparison to the XT series of Kohler engines used in the Viking LB 540, the HD675 runs for longer before needing oil changes and air filter replacements. Longer life and less maintenance. What’s not to love?
Even filling up on fuel is made easier too as the tank on the RL 540 is designed with a 45-degree angled and bigger fuel neck. Easier to get all your fuel in without spilling a drop.
With OHV (overhead valve) technology, it has good fuel efficiency too.
The 1.4L fuel tank gives hours of run time. Not that you’ll need it. Given the engine power, this is a scarifier that’ll breeze through grass blades even on clay like soil, and when damp and with ease… thanks to what Stihl coins as Consistent-CutTM technology.
All that means is that the machine will go over lumps and bumps and won’t slow down.
That’s the thing with 4-stroke engines. They have two speeds. Fast, and faster!
You can’t idle these things over dodgy bits of ground.
For that reason, if you’re in the midst on renovating a worse-for-wear lawn, use this with extreme caution. It is unforgiving as it may chuck loose debris, stones, sticks out of the back. The Stihl RL 540 really is for meticulously kept lawns.
Fixed Blades
The RL540’s fixed blades.
The Stihl RL540 is equipped with fixed blades with a working width of 38cm!
For lush lawns, fixed blades are the definitive way to go. Getting worn out lawns up to par with the best is done with powered scarifiers that have either swing blades or flail type blades.
The reason being that when you use swing blades, or floating blades, when you hit an obstacle, they’ll bounce away from it.
With fixed blades, (and in particular with this one considering the sheer power of the engine), the blades are more likely to be damaged if it comes into contact with a stone, dogs’ bone or the likes.
The advantage of the fixed blades on manicured lawns is that the scarifier can go deeper.
With a working width of 38cm, you can get moss and thatch off your lawn with very little effort, and penetrate the ground to a depth of a few millimeters making way for nutrients and air to get into the soil, helping your lawn to breathe.
Single Pull Start-Up (even from cold)
There’s nothing worse than petrol garden machinery that you have to tug tirelessly on the pull cord to get the thing to start.
Stihl are huge fans of Kohler engines. Under the hood of the RL 540 is the Smart-ChokeTM technology.
You don’t even need to prime this petrol scarifier to get it going.
The advantage here is that there is zero risk of flooding the engine. Ever done that?
That’s regardless of whether you’re starting the engine from cold, or a warm start.
If you’re interested in understanding how Smart-ChokeTM works, check this video out.
Maneuverability
The whole machine weighs just 33kg. Not exactly lightweight, but easy enough for anyone with a little upper body strength.
That’s not what makes it stand out though. It’s the design of the Stihl RL 540.
The height adjustments are done by a lever located on the handle, the same as the older Viking alternative.
When you reach the end of one row, you simply raise the lever to lift the height of the blade, turn around, drop the height and work your way back along the next row.
You don’t need to stop and start the machine, nor do you risk ripping your lawn to shreds at every turn.
The wheels are designed to be easy running too with good treads that grips ground well… even on damp grass.
Conveniently, there’s also a carry handle located right on the housing unit – the handles fold down for compact storage and easy transportation.
Handy if you’re doing more than your own lawn, or need to get it to the very back of your shed.
The Pros of the Stihl RL 540
Robust engine
Stihl do terrific designs, but it’s Kohler that powers them. This is no different and it does a top-notch job!
Sturdy polymer housing unit
It can withstand hits from obstacles (accidents happen, but do clear up to protect the blades). Those won’t stand up to many obstacles.
Single pull start
A must-have for any petrol-powered garden machinery.
Compact for easy storage and transportation
As mentioned earlier, relatively light and easily foldable handles.
Fixed blades
As pictured above, great for scarifying deeper into lawns. Perfect for getting plenty of aeration and nutrients into the soil.
Lever controlled height adjustment on the handlebar
You can choose just how deep you want to go, 1 being the lightest and 6 being the heaviest. Allowing you to find what works best for you.
Available parts
Stihl products are guaranteed to have parts available for 10-years from the date the last model of any product line is sold.
They have kept their word on that promise!
When Viking machines disappeared from the market in 2019, parts are still available. The part numbers may be different, but owners of Viking machines can contact a Stihl dealership (or customer support) with the make and model number of any Viking machine made in the past 10-years to have new parts delivered to the local dealership.
The Drawbacks
No collection bag supplied as standard
There is a grass collection bag you can buy as an accessory. Personally, I think this would be a waste of time.
Being 50L and considering that this machine is really suited to mid to large sized lawns, (over 300m2) 50L isn’t much capacity.
You’d be emptying the bag too frequently.
It’s much easier to lift the flap like we did in the video, leave the clippings and then blow it rake it up and green bin it/bag it.
No electric start option
Given the advancements of modern technology and the wide availability of electric start petrol mowers, is it wrong to come to expect it on other petrol machinery?
That said, it does have the single-pull rope start so it’s not back-breaking to get going.
Back plate
As you can see in the video, the back plate closes automatically, there’s no real way to hold this up; hence why we used garden wire on ours.
The problem with leaving it closed is that after a few lines, the scarifier would clog up simply because of all the thatch that would build up inside.
The Verdict
The Stihl RL 540 definitely has a lot going for it. The engine is the stand-out part.
If you know what you’re doing with petrol machines and don’t mind the annual servicing – replacing filters and dealing with oil changes more frequently; a second-hand Viking LB 540 would give the same features, for less cost. Parts are still available.
Talking of the Viking LB540, and for the fans of the green Viking gardening machines, you’re in luck. If you didn’t know, they’re Stihl now, and have been since 1992, – as a subsidiary!
In 2019, Stihl made the decision to focus stronger on marketing under the Stihl Group brand.
Viking products are branded under the Stihl Group exclusively now. As such, the machines are orange instead of green. That’s what’s different.
The Stihl RL 540 scarifier is technically the Viking LB 540 scarifier – in orange.
(If you want to compare specs, this is the Stihl RL 540 manual, and this is the Viking model manual).
The only difference between the RL 540 and Viking LB 540 is the colour and the engine.
For a new scarifier, Viking’s aren’t made any more. You’ll have to settle for the Stihl RL 540 in orange with a better engine.
For either model, forego the collection bag when using these powered scarifiers. It’s more of a nuisance to keep stopping to empty the bag.
