STIHL MS 661 CM Chainsaw: Professional power for large fellings and large logs
The STIHL MS 661 CM is a professional forestry chainsaw designed to tackle demanding felling tasks, cutting large diameter logs and intensive work in the woods .
The 91.1 cm³ engine develops 5.4 kW / 7.3 hp , with a structure designed to offer a large torque reserve when the bar is heavily engaged in the wood.
This version with a 28" bar (approximately 70 cm) and 3/8" pitch chain is particularly suitable for those who work professionally on large diameter trees and want a machine capable of maintaining high productivity even in the most demanding conditions.
Who is this chainsaw suitable for?
- Professional lumberjacks
- Forestry workers
- Agricultural and forestry companies
- Those who frequently carry out large-scale felling
- Those who work on logs of considerable diameter
- Those who need long bars and high torque under load
Why choose STIHL MS 661 CM?
91.1 cm³, 5.4 kW engine
The large displacement offers significant power reserves when working with long bars or large-diameter logs.
Approximately 70cm (28") bar
A configuration designed for demanding felling and for tackling large logs without being limited by a guide bar that is too short.
3/8" pitch chain
Robust professional configuration suitable for high productivity forestry work.
STIHL M-Tronic system
It electronically manages the engine operation and automatically adapts carburetion and ignition to the operating conditions.
Great torque reserve
The advantage of the large displacement emerges above all when the bar enters deeply into the trunk and the chain works under heavy load.
Adjustable oil pump
It allows you to adapt the lubrication of the cutting unit according to the length of the bar and the working conditions.
Professional construction
It is designed for operators who use the chainsaw very frequently and require reliability and continuity of work.
When it's NOT the right choice
- If you only prepare small amounts of firewood
- If you use the chainsaw a few times a year
- If you work mainly on small diameters
- If you need to do mainly light limbing
- If you are looking for an agile machine for very dynamic jobs
- If you have no experience with large-displacement professional chainsaws
The MS 661 CM is a specialized machine: the more the diameter of the wood, the length of the bar and the intensity of the work increase, the more its displacement, torque and ability to maintain high performance under load are appreciated.
STIHL MS 661 CM vs. STIHL MS 500i: Which One Should You Choose?
The MS 661 CM and the MS 500i are both professional, high-performance chainsaws, but have very different characteristics.
The MS 661 CM offers 91.1 cm³ and 5.4 kW , while the MS 500i uses a 79.2 cm³ and 5.0 kW engine. The difference in power is not huge, but the 661 has a significantly larger displacement and is therefore more suited to large felling operations and use with long bars.
| Characteristic | STIHL MS 661 CM | STIHL MS 500i |
|---|
| Category | Professional - large reductions | High performance professional |
| Displacement | 91.1 cm³ | 79.2 cm³ |
| Power | 5.4 kW / 7.3 hp | 5.0 kW / 6.8 hp |
| Machine body weight | Approximately 7.5 kg | Approximately 6.3 kg |
| Power-to-weight ratio | Approximately 1.4 kg/kW | Approximately 1.24 kg/kW |
| Configuration bar | Approximately 70cm (28") | 63 cm (25") |
| Chain pitch | 3/8" | 3/8" |
| Engine management | STIHL M-Tronic | STIHL Injection |
| Acceleration | Very high | Extremely fast |
| Long bars | Particularly suitable | Very good |
| Handling | More massive | Lighter and more responsive |
| Strong point | Displacement, torque and large reductions | Weight/power and acceleration |
| Ideal for | Large logs and very heavy work | Professional who wants power with greater agility |
👉 In summary: choose the STIHL MS 661 CM if your work is mainly focused on large felling operations, large diameters and frequent use of long bars.
Choose the STIHL MS 500i instead if you want very similar performance in terms of power, but with around 1.2 kg less body weight and extremely rapid response thanks to electronic injection.
Fabrizio 's usage tips and suggestions
In my opinion, the MS 661 CM should be chosen when the priority is not having the lightest machine possible, but having torque, displacement and the ability to work with long bars .
We're talking about a chainsaw of over 90 cm³: when the bar enters a large trunk and is almost completely engaged, the difference compared to a smaller machine really begins to be felt.
The real difference compared to the MS 500i
On paper the power difference seems limited: 5.4 kW versus 5.0 kW .
But in my opinion that is not the main fact.
The MS 661 CM has 91.1 cm³ , almost 12 cm³ more than the 500i. This translates above all into a character more oriented towards torque and jobs where the chainsaw remains under load for a long time.
The MS 500i, on the other hand, focuses more on lightness and acceleration.
The sensations in real use
- Very full-throttle motor: offers a great feeling of torque when cutting gets challenging.
- 28" bar: suitable for serious work on large diameters.
- Great stability when cutting: the higher weight can become an advantage in heavy jobs.
- M-Tronic: keeps the engine automatically regulated in different operating conditions.
- Specialized machine: designed for jobs where a smaller chainsaw would begin to be used close to its limits.
When I really recommend it
I recommend the MS 661 CM especially to those who:
- carries out large-scale slaughters frequently;
- works professionally on very large logs;
- often uses long bars;
- wants large torque reserves under load;
- does not consider weight as the main selection criterion;
- Look for a specific machine for heavier forestry work.
An aspect that many underestimate
A bar of about 70 cm requires particular attention to lubrication.
The longer the bar, the larger the surface area that needs lubrication. For this reason, I would frequently check the chain oil, the bar groove, and the lubrication hole .
The adjustable oil pump also allows you to adapt the amount of lubricant to the working conditions.
Don't use it with a dull chain
On a chainsaw of this power, working with a dull chain means wasting a lot of the available performance.
The machine should not be pushed into the log: with a properly sharpened chain, the cutting unit should pull the chainsaw into the wood.
I would therefore frequently check the sharpness, tension and condition of the bar .
MS 661 CM or MS 500i?
Here I would make a very simple distinction.
If I had to work every day with a very powerful machine, alternating felling, cutting and various movements during the day, I would look at the MS 500i with great interest.
It has 5 kW but weighs around 6.3 kg: its power-to-weight ratio is better and the electronic injection gives it an extremely rapid response.
If the work was mainly concentrated on large trees, large sections and long bars , I would choose the MS 661 CM .
How much does a 1.2 kg difference really matter?
A lot, if you have to constantly move the chainsaw.
Less so, if most of the work involves keeping the bar engaged inside large logs.
And this is exactly what, in my opinion, divides the two machines:
MS 500i: more dynamic, lighter and more responsive.
MS 661 CM: bigger, fuller and more oriented towards heavy work.
Which one would I choose?
For a very varied professional forestry use I would probably choose the MS 500i , because 5 kW with 6.3 kg is hard to ignore.
However, if you already knew that you would mainly work on very large diameters and would frequently use a 70 cm or larger bar, then the MS 661 CM would make more sense.
👉 I would therefore not choose the 661 because it is “more powerful”, but because it is a machine more specialized in large felling.
Pre-shipment inspection
Before shipping, we check that the chainsaw is complete, correctly assembled and that the bar, chain and all the components required by the configuration are present.
My final advice
If you are looking for a professional chainsaw to tackle large fellings, large logs and very heavy jobs , the STIHL MS 661 CM with 28" bar is a machine designed exactly for this type of use.
👉 Compared to the MS 500i you give up a bit of lightness and responsiveness, but you gain displacement, torque and a greater predisposition for jobs where long bars and large diameters are the norm.
Questions & Answers about the STIHL MS 661 CM chainsaw
Is the STIHL MS 661 CM a professional chainsaw?
Yes. It is a large-displacement professional forestry chainsaw, designed primarily for large-scale felling and processing of large logs.
How much power does the MS 661 CM develop?
The 91.1 cm³ engine develops 5.4 kW / 7.3 hp .
How much does it weigh?
The machine body weighs approximately 7.5 kg without bar, chain and fuel.
What is the M-Tronic system for?
It electronically regulates engine operation according to operating conditions, reducing the need for manual interventions on the carburetion.
MS 661 CM or MS 500i, which is better?
The MS 661 CM is best suited for heavy felling, large diameters, and long bars. The MS 500i is lighter and more responsive, offering a better power-to-weight ratio.
Is the MS 661 much more powerful than the MS 500i?
No. The difference is approximately 0.4 kW. The main advantage of the MS 661 CM is its larger displacement and greater suitability for heavy-duty work under load.
Is the 28" bar suitable for large fellings?
Yes. The approximately 70 cm bar is designed specifically for tackling large diameter logs and jobs where a shorter bar would be limiting.
Is it also suitable for preparing firewood?
Yes, but for normal household quantities, it's generally oversized. It makes more sense when diameters and wood quantities are important.
What maintenance does such a long bar require?
The lubrication, tension and sharpness of the chain should be checked frequently, as well as the oil groove and hole in the bar kept clean.
Is the product checked before shipping?
Yes. Before shipping, we check that the chainsaw is complete, correctly assembled, and that all required components are present.
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