Stihl MS 310 vs MS 390 (Field Comparison)

The MS 390 has a small power advantage: 64.1 cm³ and 3.4 kW, versus the MS 310’s 59 cm³ and 3.2 kW. That difference may help during sustained cutting, but it does not make the 390 a different class of saw. Condition, chain sharpness, bar setup, and operator skill often matter more. Choose by workload and verified saw condition.

If you are weighing these legacy gas saws against buying another tool, a well-maintained saw sized to your work can avoid needless replacement and waste. But “more engine” is not automatically a greener or better choice: fuel use depends on the work and how the saw is maintained. The practical decision here is whether the MS 390’s modest extra output is worth its added weight and purchase price.

MS 310 vs. MS 390 specifications

These figures give you a fair starting point, not a promise of cutting speed. Published specifications can vary by market or version, so check the saw’s identification and matching STIHL manual before buying parts, choosing a bar, or servicing it.

*Bare weight excludes the cutting attachment and may vary by version. Compare the exact saw and manual rather than relying on a listing.

The power-to-weight figures are close: using the figures above, the MS 310 is about 0.52 kW/kg and the MS 390 about 0.53 kW/kg. That small calculated edge does not establish real cutting speed. Wood type, chain condition, bar length, and cutting technique all affect how quickly a saw works.

Both models use a 3/8-inch pitch in common configurations, but pitch alone is not enough to select a chain. Pitch, gauge, and drive-link count must match the bar and sprocket. Take the markings from the actual saw and bar to a dealer or use the correct manual.

How the extra power feels in the field

The MS 390’s additional output is most relevant when the saw stays under load for longer cuts. The difference is modest, though; it should not be treated as a reason to use a longer bar or force the saw through wood. A sharp, correctly matched chain can matter more than the model badge.

I compare these saws by holding the setup as constant as possible: similar wood, equally sharp chains, compatible bars, and safe, repeatable cuts. That approach helps separate a model difference from a dull chain or worn machine. I would not claim a measured time advantage without a controlled test on the actual saws.

• Choose the MS 310 if your work is occasional bucking, firewood cutting, or felling within your training and the saw’s approved setup, and the individual machine is sound.
• Consider the MS 390 if you regularly make sustained cuts and both saws are in similar condition and priced fairly. Its extra power may help, but it will not overcome poor maintenance or a dull chain.
• Choose neither without inspection if the saw has uncertain service history, a faulty chain brake, oiling problems, damaged parts, or mismatched bar and chain components.

Field scenarios: which saw fits?

These examples are decision scenarios, not reports of a specific job or a controlled test. They show how to apply the specification difference to common tasks without assuming that engine size alone determines the outcome.

Occasional firewood: If the MS 310 is in better condition, it may be the more sensible buy. A sharp chain, sound bar, and working oil system matter more than the MS 390’s small power lead.

Frequent bucking: If both saws are equally healthy and the cuts involve repeated, sustained load, the MS 390 is the reasonable candidate to compare. Test safely with matching setups if possible; do not expect the power rating to predict a fixed time saving.

Felling or larger wood: Neither model makes a difficult tree safe by itself. Tree lean, defects, overhead hazards, escape routes, and the operator’s training determine whether the job is suitable. Ask a qualified arborist when the tree or site is beyond your skill.

Bar, chain, fuel, and safety setup

Setup means confirming that the saw’s parts fit each other and that its safety systems work before cutting. The right setup is model- and market-specific: use the manual for the exact saw, and check markings on the bar, chain, and sprocket rather than guessing from displacement.

Use only bar lengths approved for the exact model and cutting setup. Choose the shortest approved bar that safely reaches the work. A longer bar adds load and can increase kickback exposure; there is no simple bar-to-engine-size ratio that makes a setup safe.

Before work, confirm all three chain-fit details:

• Pitch: the spacing that matches the sprocket and bar nose.
• Gauge: the drive-link thickness that fits the bar groove.
• Drive-link count: the number of links needed for that bar.

Do not install a chain based only on its pitch. Set depth gauges, often called “rakers,” to the installed chain maker’s instructions; there is no universal setting for every chain. Check tension, cutters, bar rails, sprocket, and chain brake. Use proper adhesive bar-and-chain oil, then verify oil delivery using the manual’s test procedure. Do not assume a fixed oil-flow rate.

For fuel, follow the exact manual and oil-maker instructions. These models are commonly specified for fresh unleaded gasoline mixed 50:1 with suitable air-cooled two-cycle oil, but confirm the requirement for your saw. Never run straight gasoline or an incorrect mix; inadequate oil can cause rapid overheating and engine seizure.

Inspect the site for overhead hazards, wind, lean, dead limbs, bystanders, traffic, utilities, and a clear retreat path. Wear a helmet, eye and hearing protection, chainsaw-rated leg protection, gloves, and protective boots. Apply ANSI Z133 work practices where they apply. OSHA 1910.266 covers certain logging operations; it does not automatically apply to every landscaping task.

Safe operation and the buy-side inspection

A field comparison is useful only if both saws are safe to operate. Before starting, inspect the chain brake, throttle lockout, chain catcher, handles, fasteners, fuel and oil caps, and chain condition. Clear the work zone, plan a retreat path, and do not work alone on hazardous tree operations.

Start the saw as its manual directs, with it secured and the chain clear of people and objects. At idle, the chain must stop. If it moves at idle or the saw will not idle safely, stop and fix the issue before cutting. Warm the engine without prolonged idling.

Keep two hands on the saw and stable footing. Keep the bar nose clear of the material: contact between the upper part of the nose and wood can cause rapid kickback toward you. Avoid tip-boring unless trained and equipped for it, and never cut above shoulder height. A working chain brake can reduce risk, but it cannot prevent every injury.

When bucking, make sure the log is stable and understand where it is under compression or tension. For felling, plan the notch, preserve sound hinge wood, and make a suitable back cut. Uncertain lean, tree defects, overhead hazards, or a large tree call for a qualified arborist.

Engage the chain brake when moving. Shut down before adjustments or clearing a jam, and let the saw cool before refueling. Stop for abnormal vibration, loose parts, damaged chain, or lost oil delivery. These faults can make either model an unsafe purchase, whatever its rated power.

Maintenance, condition, and seasonal storage

Maintenance is the work that keeps a saw cutting safely and helps you compare its true condition with another saw. On an older MS 310 or MS 390, service history and inspection can matter more to value than a small difference in engine size.

Clean the air filter, cooling fins, starter screen, sprocket cover, and bar groove. Clear the oil inlet, check oil-hole alignment, and flip the bar as the manual directs. Look for bar-rail wear or burrs. Sharpen with the file size, angle, and depth-gauge setting specified for the chain installed, not a generic model-specific setting.

Do not tune the carburetor by ear or defeat safety or emissions limits. Carburetor adjustment and maximum-speed checks call for the correct manual, a tachometer, and competent service. A lean setting can overheat the engine and damage the piston. If the saw’s history is unclear, budget for a qualified inspection rather than assuming a running engine is a healthy one.

For extended storage, follow the manual’s fuel-system instructions. Use fresh, correctly mixed fuel during operation, keep fuel away from ignition sources, and store fuel and bar oil in closed, labeled containers. Before returning the saw to service, inspect hoses, filter, spark plug, chain brake, controls, bar, chain, and oiling system. Repair defects before cutting.

Which saw should you buy?

The MS 390 offers a modest output increase, while the MS 310 is slightly lighter. Neither wins every comparison. Your best choice depends on the work, approved setup, machine condition, and price—not on displacement alone.

When I assess a used saw, I start with safe function and condition, then compare the actual cutting setups and costs. Ask for the exact model and serial information, matching manual, service records if available, and details about the bar and chain. Confirm that the chain brake, throttle controls, and oiling system work before purchase.

A practical decision rule is straightforward: buy the healthier saw if the two are similarly priced and fit your workload. Pay extra for the MS 390 only if you have a real need for its small power advantage and it is in comparable condition. If either saw has a safety fault, mismatched parts, or uncertain engine health, walk away or include qualified repair costs in the price.

Frequently asked questions

These short answers address the most common buying and setup questions. Confirm details against the manual and markings on the specific saw, because legacy models and market versions may differ.

Is the MS 390 more powerful than the MS 310?

Yes. The commonly listed ratings are 3.4 kW for the MS 390 and 3.2 kW for the MS 310. That is a modest difference, not a guarantee of faster cutting in every type of wood.

How much larger is the MS 390 engine?

The MS 390 is commonly listed at 64.1 cm³, compared with 59 cm³ for the MS 310. Displacement measures engine size; it does not by itself tell you how quickly a saw will cut.

Is the MS 310 lighter?

Yes. Common bare weights are about 6.1 kg (13.4 lb) for the MS 310 and 6.4 kg (14.1 lb) for the MS 390. Bar, chain, fuel, and oil add weight during use.

Which is better for firewood?

Either can suit firewood work if it is healthy, safely set up, and appropriate for the wood and operator. If condition and price are similar, choose the MS 390 for its small power advantage or the MS 310 for its lower bare weight.

Can I put a longer bar on the MS 390?

Only use a bar length approved for the exact model and setup. More engine displacement does not make every longer bar safe or suitable; a longer bar adds load and kickback exposure.

Do the MS 310 and MS 390 use the same chain?

They commonly use 3/8-inch pitch, but that does not guarantee the same chain fits. Match pitch, gauge, and drive-link count to the saw’s sprocket and installed bar.

What fuel mix should I use?

These saws are commonly specified for a 50:1 gasoline-to-two-cycle-oil mix, but check the manual for your exact model and market. Never use straight gasoline or an unapproved mix.

Is either model suitable for felling?

Both can be used for suitable felling work by a trained operator with the correct setup. Tree size, lean, defects, overhead hazards, and site conditions matter; hire a qualified arborist when the job is beyond your skill.

What should I check before buying a used one?

Check the chain brake, throttle controls, chain catcher, oil delivery, bar and chain match, engine condition, and service history. Do not buy a saw with a failed safety system or unresolved lubrication problem for cutting use.

Which one should I buy if both cost the same?

Buy the one in better condition that fits your work. If both are equally sound, choose the MS 390 for its modest power edge or the MS 310 if lower weight matters more.

(This article was written by one of our staff writers, Marcus Thorne. Visit our Meet the Team page.)