STIHL® MS 400 C-M Professional-Grade Gas Chainsaw

The STIHL MS 400 C-M is a high-performance professional chainsaw built for forestry crews, arborists, experienced landowners, and serious firewood operators who want more cutting power than the MS 362 C-M without moving to the larger MS 462 C-M platform.

Its 66.8 cc STIHL 2-MIX engine produces 4.0 kW or approximately 5.4 hp, while the powerhead weighs approximately 5.8 kg. This gives the MS 400 C-M a power-to-weight ratio of just 1.45 kg per kW, placing it remarkably close to the larger MS 462 C-M while remaining more manageable for limbing, bucking, and mixed forestry work. (stihl.ca)

The MS 400 C-M was also the first production chainsaw fitted with a magnesium piston as standard. STIHL used the lighter piston material to increase displacement and power without adding the weight normally associated with a larger engine. (stihl.ca)

Our Recommendation

We recommend the STIHL MS 400 C-M to professional and highly experienced operators who regularly find the MS 362 C-M working near its limits, but do not need to carry a full 70 cc felling saw.

It is an especially strong choice for operators who spend their day moving between limbing, felling, and bucking. The MS 400 C-M provides substantially more cutting output than the MS 362 while adding only about 200 grams to the listed powerhead weight. That makes the upgrade easy to justify when faster production matters. (stihl.ca)

The MS 400 C-M is not automatically the right saw for every acreage owner or firewood cutter. The MS 391 remains a capable and more economical option for seasonal rural use. The professional MS 400 earns its higher price through lower weight for its output, faster acceleration, M-Tronic engine management, professional filtration, and construction intended for frequent forestry work.

Operators primarily cutting large timber with longer guide bars should also compare the MS 462 C-M. The MS 462 provides greater displacement and power with only a modest increase in powerhead weight.

Best Suited For

The STIHL MS 400 C-M is particularly well suited to:

• Professional forestry and tree care

• Felling and processing medium-density timber

• Fast limbing and delimbing

• Regular firewood production

• Storm and windfall cleanup

• Commercial acreage and rural property work

• Operators who want more output than the MS 362 without carrying a much larger saw

• Experienced users who regularly run 18-inch, 20-inch, or 25-inch cutting attachments

66.8 cc Professional Performance

The MS 400 C-M uses a 66.8 cc engine producing 4.0 kW. STIHL lists the saw at approximately 5.8 kg without fuel, guide bar, or chain. (stihl.ca)

That output gives the MS 400 C-M a noticeable advantage when cutting:

• Medium and larger softwood

• Hardwood firewood

• Repeated logs during production cutting

• Storm-damaged trees

• Timber that places sustained demand on a 20-inch bar

• Larger limbs and stems that slow down a 50 cc or 60 cc saw

The MS 400 is not simply a larger-displacement MS 362. Its professional engine and lightweight construction allow it to cut with greater authority while retaining the handling expected from a versatile forestry saw.

Magnesium Piston Technology

The defining feature of the MS 400 C-M is its magnesium piston.

Most chainsaw pistons are made from aluminum. STIHL developed a magnesium alloy piston that is lighter while remaining suitable for the heat, speed, and stress found inside a professional chainsaw engine. The reduced piston weight allowed STIHL to increase displacement and rated power without significantly increasing the saw’s overall weight. (stihl.ca)

STIHL states that the magnesium piston also supports:

• A higher maximum rotational speed

• Improved cutting performance

• Better power-to-weight

• Reduced vibration transmitted through the machine

• Professional durability under challenging forestry conditions

The practical benefit is not that the owner needs to think about the piston during normal operation. It is that the MS 400 delivers near-70 cc performance in a saw that remains close to the MS 362 in weight.

Where the MS 400 C-M Fits in the STIHL Lineup

The MS 400 C-M occupies a valuable position between the 59 cc MS 362 C-M and the larger MS 462 C-M.

The MS 362 remains a balanced all-around professional saw for medium timber and regular firewood. The MS 462 is built for larger felling and bucking work. The MS 400 bridges the gap by delivering a major increase in output without a dramatic increase in weight.

This makes it particularly useful for operators who need one saw to cover:

• Limbing

• Felling

• Bucking

• Firewood processing

• Storm cleanup

• General forestry work

The MS 400 may not replace a larger saw for long-bar work in oversized timber, but it can reduce how often an operator needs to carry the heavier model.

STIHL M-Tronic Engine Management

The “C-M” designation identifies STIHL’s M-Tronic electronic engine-management system.

M-Tronic regulates ignition timing and fuel delivery while accounting for changing operating conditions such as:

• Temperature

• Elevation

• Fuel quality

• Engine temperature

• Air-filter restriction

• Cutting load

This helps the MS 400 maintain consistent performance without requiring the operator to manually adjust conventional high-speed and low-speed carburetor screws. (stihl.ca)

For operators working in Alberta, this is useful when moving between cold winter cutting, hot and dusty summer work, and different elevations across Calgary, the foothills, and mountain properties.

M-Tronic does not eliminate maintenance. Fresh fuel, a clean filter, open cooling passages, proper chain lubrication, and a sharp chain remain essential.

Choosing a Guide-Bar Length

The current Canadian STIHL listing identifies an 18-inch configuration for the MS 400 C-M, while professional users may select other suitable cutting attachments based on availability and application. (stihl.ca)

18-Inch Bar

An 18-inch bar creates a responsive and manoeuvrable professional setup.

It is a strong choice for:

• Limbing and delimbing

• Medium timber

• Mixed forestry work

• Carrying the saw for long periods

• Operators who prioritize speed and handling

With an 18-inch bar, the MS 400 has abundant power available and can accelerate quickly through repeated cuts.

20-Inch Bar

A 20-inch bar is likely to be the most versatile configuration for many professional users.

It provides useful reach while retaining much of the saw’s balanced handling. It is well suited to:

• Regular firewood production

• Felling medium trees

• Bucking mixed log sizes

• Storm cleanup

• General professional forestry

25-Inch Bar

A 25-inch setup can take advantage of the MS 400’s displacement when larger timber is encountered.

It is most appropriate when:

• Longer reach is regularly useful

• Bucking and felling are more common than detailed limbing

• The operator understands the added oiling and maintenance demands

• The wood size justifies the additional bar weight

A longer guide bar does not increase engine power. Operators spending most of their day in smaller timber may be faster and less fatigued with an 18-inch or 20-inch setup.

Long-Life Air-Filtration System

The MS 400 C-M uses STIHL’s professional long-life filtration system.

A pre-separation system removes larger sawdust and debris before the air reaches the primary filter. The HD2 filter then captures finer particles, helping protect the engine and extend cleaning intervals. (stihl.ca)

This is particularly useful when cutting:

• Dry or dead timber

• Dirty bark

• Windfall close to the ground

• Firewood stored in dusty areas

• Beetle-damaged wood

• Timber during Southern Alberta’s dry summer conditions

The system extends filter life, but it does not make the filter maintenance-free. A restricted or damaged filter can reduce performance and allow abrasive contamination into the engine.

Adjustable Chain-Oil Pump

The MS 400 C-M includes a controlled-delivery oil pump that allows the operator to adjust chain-oil output for the installed guide bar and cutting conditions.

Oil delivery can be increased for:

• Longer guide bars

• Dry or abrasive timber

• Sustained heavy cutting

• Dusty working conditions

• Cold weather when lubricant flow may change

STIHL states that the adjustable system can reduce oil consumption by up to 50 percent when correctly configured. (stihl.ca)

Oil flow should never be reduced below the amount required to keep the bar and chain properly lubricated. Inadequate oil can damage the guide bar, chain, sprocket, clutch area, and oiling system.

STIHL Ematic Lubrication System

The STIHL Ematic system combines the guide bar, Oilomatic saw chain, and adjustable oil pump to direct chain lubricant toward the areas where it is needed.

This helps reduce unnecessary oil loss while maintaining lubrication during sustained forestry work. (stihl.ca)

Operators should regularly inspect:

• Chain-oil level

• Oil delivery from the saw

• Guide-bar oil holes

• The bar groove

• Drive sprocket condition

• Signs of excessive heat or discolouration

A properly operating lubrication system is essential to realizing the saw’s cutting performance.

Manual Decompression Valve and ElastoStart

The MS 400 C-M includes a manual decompression valve that releases part of the cylinder pressure during starting.

This reduces the effort required to pull the starter rope and decreases stress on the starting components. The valve closes once the engine fires. (stihl.ca)

STIHL ElastoStart further smooths the starting process by reducing the sudden force transferred through the starter handle.

These systems help make a high-compression professional saw easier to start, but the operator must still follow the proper cold-start and warm-start procedure.

Professional Anti-Vibration System

The MS 400 C-M uses STIHL’s anti-vibration system to reduce the amount of engine vibration transferred to the front and rear handles.

Buffer and spring elements help isolate the handles from the powerhead, supporting greater comfort during long periods of limbing, felling, and bucking. (stihl.ca)

Reduced vibration does not eliminate fatigue. Operators should continue taking regular breaks and stop before tiredness affects grip, balance, judgment, or reaction time.

Captive Bar Nuts and Side Chain Tensioning

Captive bar nuts remain attached to the sprocket cover when loosened, reducing the chance of losing them during chain adjustment or guide-bar service.

This is particularly useful when maintenance is performed:

• In snow

• In leaves or tall grass

• On a remote jobsite

• In the back of a service truck

• Away from a workshop

The MS 400 also uses side-mounted chain tensioning, allowing the adjustment screw to be reached from the side of the powerhead. (stihl.ca)

Chain tension should be checked before work, after installing a new chain, after the first few cuts, and periodically as the chain heats and cools.

STIHL Professional Chainsaw Comparison

STIHL’s published comparison places the MS 400 C-M between the MS 362 C-M and MS 462 C-M, with 4.0 kW of power, a 5.8 kg powerhead, and a 1.45 kg/kW power-to-weight ratio. (stihl.ca)

STIHL MS 400 C-M vs MS 362 C-M

The MS 362 C-M and MS 400 C-M are close in physical size, but the MS 400 offers a major increase in output.

The MS 362 remains a capable and well-balanced professional saw. It is the sensible choice when medium timber is the primary workload and the additional output of the MS 400 would rarely be used.

The MS 400 becomes the stronger investment when production speed matters. STIHL increased output by 0.5 kW while adding only about 0.2 kg to the listed powerhead weight. (stihl.ca)

STIHL MS 400 C-M vs MS 391

The MS 391 and MS 400 have similar displacement, but they are designed for very different users.

The MS 391 remains a practical choice for acreage owners and firewood cutters who use their saw seasonally and prioritize purchase value.

The MS 400 C-M is the much stronger option for frequent use. It produces considerably more power, weighs less, and automatically manages fuel and ignition settings as conditions change.

STIHL MS 400 C-M vs MS 462 C-M

The MS 462 C-M is the next step up for professional felling and larger timber.

The MS 400 is generally the better all-around choice when limbing, mobility, and mixed timber remain important.

The MS 462 becomes worth the step up when the operator regularly works with large trees, longer bars, and demanding felling cuts. The weight difference is relatively small, so wood size and bar requirements should drive the decision.

STIHL MS 400 C-M vs MS 500i

The MS 500i is a larger, fuel-injected professional saw built around exceptional acceleration and power-to-weight.

The MS 400 C-M is usually the better choice when:

• Medium-to-large timber is the main workload

• An 18-inch to 25-inch bar covers most jobs

• Lower purchase cost matters

• Fuel consumption and handling are priorities

• The operator does not need near-80 cc output

The MS 500i becomes more valuable when:

• Large timber is encountered regularly

• Rapid acceleration directly improves production

• Longer bars are frequently required

• The operator works in high-output forestry

• Maximum professional power-to-weight is a priority

The MS 400 offers substantial professional performance without automatically moving the customer into the cost, output, and fuel demands of the MS 500i.

What to Know Before Buying the MS 400 C-M

It is a professional forestry saw

The MS 400 is designed for frequent and demanding work. An occasional homeowner or seasonal firewood cutter may not gain enough value from its higher price and output.

It is very close to the MS 462 in weight

The MS 462 weighs only slightly more in STIHL’s published comparison. Customers regularly cutting large timber should compare both models carefully rather than selecting the MS 400 solely because it is lighter. (stihl.ca)

The magnesium piston is not a maintenance item

The magnesium piston is an internal engineering advantage. It does not require a special operating procedure, but normal fuel, filtration, cooling, and lubrication maintenance remains essential.

M-Tronic does not correct poor maintenance

Electronic engine management cannot compensate for stale fuel, a blocked filter, obstructed cooling fins, insufficient bar oil, or a dull chain.

Longer bars change the saw’s balance

A 25-inch bar provides more reach, but an 18-inch or 20-inch setup may deliver better handling and productivity in smaller timber.

Professional power requires professional technique

The MS 400 accelerates quickly and cuts aggressively. Appropriate training, protective equipment, and an understanding of kickback, compression, tension, and felling hazards are essential.

Fuel and Bar Oil

The MS 400 C-M requires:

• Fresh gasoline mixed with high-quality two-cycle oil

• Separate bar and chain oil for the cutting attachment

For operators who use the saw intermittently, STIHL MotoMix can simplify fuel storage and reduce errors associated with mixing or aging pump gasoline.

Professional crews mixing their own fuel should use suitable fresh gasoline and STIHL two-cycle oil at the specified ratio.

The chain-oil tank should be checked whenever the saw is refuelled. Adjust oil delivery to suit the installed guide bar, chain, wood condition, and operating temperature.

Chain Care and Sharpening

A professional saw can only produce professional cutting performance when the chain is sharp and correctly maintained.

Signs the chain requires attention include:

• Fine sawdust rather than defined chips

• Slower cutting

• The saw pulling to one side

• Increased vibration

• Smoke despite adequate lubrication

• Heavy pressure required to complete a cut

• Uneven cutter lengths

• Heat discolouration on the guide bar

The pitch, gauge, and drive-link count must match the installed guide bar and drive sprocket.

Replacement chains, files, guide bars, wedges, bar oil, and protective equipment can be found through the Arns chainsaw parts and accessories collection.

Maintenance

Routine MS 400 C-M maintenance includes:

• Inspecting and cleaning the HD2 air filter

• Checking the spark plug

• Replacing the fuel filter when required

• Cleaning cooling-air passages

• Inspecting the chain brake

• Cleaning guide-bar grooves and oil holes

• Rotating and dressing the guide bar

• Inspecting the drive sprocket

• Confirming oil-pump operation

• Checking fuel and oil caps

• Inspecting the starter rope and ElastoStart handle

• Sharpening and tensioning the chain

• Inspecting the fuel and oil systems for leaks

Professional forestry work, dusty timber, and long cutting days may require more frequent inspection than the minimum maintenance schedule.

Seasonal and Cold-Weather Use

The MS 400 C-M includes a summer and winter operating arrangement with carburetor preheating to help prevent icing during cold-weather use. (stihl.ca)

For dependable winter cutting:

• Use fresh fuel

• Select suitable bar-oil viscosity

• Follow STIHL’s winter-setting instructions

• Keep snow clear of the starter and air intake

• Check the guide bar for ice buildup

• Allow the saw to warm properly

• Keep the chain sharp for frozen timber

• Return the saw to its summer setting when temperatures rise

M-Tronic can compensate for environmental changes, but it cannot prevent problems caused by unsuitable oil, contaminated fuel, or blocked airflow.

Chainsaw Safety

The MS 400 C-M should be operated only by someone familiar with professional chainsaw handling and the hazards of powerful cutting equipment.

Recommended protective equipment includes:

• Chainsaw protective pants or chaps

• Eye protection

• Hearing protection

• Protective gloves

• Chainsaw-appropriate footwear

• A forestry helmet when overhead hazards are present

• High-visibility clothing where appropriate

Operators should understand kickback, chain-brake operation, compression and tension in timber, safe escape routes, and the hazards of leaning, split, damaged, or hung-up trees.

Felling near homes, roads, vehicles, utilities, fences, or neighbouring properties should be left to a qualified professional when the operator lacks the required training and equipment.

Why Buy Your STIHL MS 400 C-M From Arns?

Arns Equipment is a family-owned STIHL dealer serving Calgary, Southern Alberta, and customers across Canada. Our team brings more than 80 years of outdoor power equipment experience to every chainsaw recommendation.

When you purchase the STIHL MS 400 C-M from Arns, our team can help you:

• Choose the correct guide-bar length

• Compare the MS 400 with the MS 362, MS 391, and MS 462

• Determine whether the larger MS 500i better suits your timber

• Select compatible chains, files, wedges, fuel, bar oil, and protective equipment

• Understand M-Tronic starting and operation

• Set the adjustable chain-oil pump correctly

• Find replacement chains, bars, and maintenance supplies

• Source repair parts through PartsHouse.ca

• Arrange local STIHL warranty support and professional chainsaw service

• Avoid purchasing more saw than your workload requires

For forestry professionals and experienced operators who want substantially more performance than the MS 362 without moving fully into the larger felling-saw class, the STIHL MS 400 C-M offers one of the most compelling combinations of power, weight, acceleration, and versatility in STIHL’s professional lineup.