Ported Stihl MS 361 Chainsaw (Field Test)
A ported MS 361 can deliver stronger response than a stock saw, but the result depends on the builder’s work, tune, chain, and wood. I would judge it by safe, repeatable cuts, not a claimed horsepower figure. Set it up with a matched 3/8-inch chain and bar, verify the builder’s tuning limits, and test only from stable ground.
Porting is internal engine work, not a simple bolt-on upgrade. There is no single “ported MS 361” specification: port shape, muffler work, carburetor setup, engine condition, and builder goals all affect how a saw runs. That is why a field test should start with the saw’s build details and condition, not a promise about speed or cutting time.
I assess the saw in stages: inspect it, confirm fit and safety, warm it fully, then make controlled cuts in known wood. I do not invent a measured result when no test record is available. The method below shows what to check and how to decide whether a particular saw is ready for your work.
Setup should be straightforward when the bar, chain, and sprocket match. The harder part is confirming the ported engine’s tune. Ask the builder for the intended fuel mix, carburetor settings or tuning limits, and safe operating range before cutting.
Equipment Setup and Safety Preparation
This section covers how to verify a ported MS 361 before its first cut. The saw uses a 59 cm³ two-stroke engine, but porting changes how it behaves. Confirm its build history, chain fit, controls, and builder’s tuning instructions; stock engine-speed figures are not a safe tuning target for a modified saw.
Confirm the build and fit
Ask who ported the saw and what was changed. Useful details include work on the cylinder, muffler, carburetor, and ignition, if applicable. Request the builder’s recommended fuel mix and maximum operating speed. If the seller cannot identify the work or provide tuning guidance, treat performance claims as unverified.
The MS 361’s standard chain pitch is 3/8 inch. Pitch alone does not prove fit: the chain gauge must match the bar, commonly .050 or .063 inch, and the drive-link count must suit the bar. Check the bar’s markings and chain maker’s chart before buying or fitting a chain.
| Item | Field check | Practical choice |
|---|---|---|
| Engine | Confirm 59 cm³ MS 361 identity and build history | Ask for porting and tuning details |
| Bar | Check length, gauge, and condition | Often 16–20 inches for routine work |
| Chain | Confirm pitch, gauge, and drive links | 3/8-inch pitch; match bar gauge |
| Chain tension | Pull the chain around the bar by hand with gloves | It should move freely and sit correctly in the groove |
| Oil delivery | Check oil reaches the chain during operation | Use suitable bar-and-chain oil; verify flow |
| Fuel | Use fresh mix | 50:1 by volume, unless the saw or oil maker directs otherwise |
A 16–20-inch bar is a practical range for routine bucking, not a guarantee that every cut is suitable. Longer bars add reach but also demand more power and control. Choose for the wood, saw condition, chain, and operator skill. Do not exceed the bar range approved for the saw and its parts.
Inspect the chain brake, throttle lockout, chain catcher, handles, fasteners, bar, and controls. Make sure the chain is sharp and the depth gauges follow the chain maker’s specification. About 0.025 inch (0.65 mm) is a common depth-gauge reference, but it is not universal. Lowering them too far can raise kickback and vibration risk.
Wear a helmet with face and eye protection, hearing protection, chainsaw-rated leg protection, gloves, and boots. Set firm footing, clear the work zone, and plan an escape route. For applicable logging work, OSHA rules call for at least two tree lengths between a tree being felled and other workers. Felling requires task-specific training and controls.
Takeaway: A matched setup and clear build history matter more than a seller’s “race saw” label.
Field Cutting and Landscaping Operation
This section sets out a controlled field test for bucking and compatible ground-level landscaping. It does not assign a universal cut time or power gain: porting varies, and wood species, moisture, chain condition, bar length, and operator technique all change the result.
Start the saw by the manufacturer’s procedure, with the chain brake engaged and the saw secured on the ground or otherwise safely restrained. Never drop-start it. Check that the chain stays still at idle, then warm the engine. Confirm smooth throttle response, brake operation, and chain lubrication before cutting.
For a useful comparison, select similar pieces of wood and use the same bar, chain condition, and cutting method. Record the wood, bar length, chain type, fuel, and any tuning notes. The point is not to chase a number; it is to see whether the saw cuts cleanly without bogging, surging, excessive heat, or poor control.
| Test condition | What to observe | What it may indicate |
|---|---|---|
| Sharp chain in clean wood | Smooth feed with steady engine sound | A useful baseline |
| Similar cut with a dull chain | Slow cutting and more pressure needed | Sharpen; do not force the saw |
| Engine hesitates or surges | Uneven response under load | Stop and have tune or fuel delivery checked |
| Chain does not oil | Dry chain or bar during operation | Stop; inspect oil level, ports, and pump system |
| Bar binds in a cut | Wood movement or poor cut planning | Stop, secure the work, and plan a safe release |
| Unusual noise, smoke, or heat | Change from normal operation | Stop and inspect before further use |
Keep both hands on the saw and your feet stable. Plan each cut for the wood’s compression and tension. If the wood shifts, the bar binds, or the saw becomes hard to control, stop. Engage the chain brake when repositioning.
Rotational kickback happens when the upper quadrant of the bar nose touches wood or another object. The bar can rise toward the operator very quickly. Keep the nose clear, avoid tip cuts, hold the saw firmly with both hands, and use a working chain brake. A ported saw’s sharper response makes sound technique especially important.
Do not cut above shoulder height or operate one-handed. Porting does not make a saw suitable for overhead work or uncontrolled felling. For landscaping, use it only for cuts within the operator’s training and the saw’s intended use.
Field scenarios: what a test can and cannot show
These are test scenarios, not claims of measured results from a specific saw. They help separate a machine issue from a setup or cutting issue before you decide whether the ported saw suits your work.
- Routine bucking: On stable ground, compare several similar cuts with a sharp, correctly matched chain. Note whether the saw feeds smoothly and remains controllable. A single fast cut does not establish a repeatable gain.
- Longer-bar work: A longer bar may reach through larger timber, but it adds load. If the saw slows, the chain binds, or control is reduced, stop and reassess bar choice and cut plan.
- Landscape cleanup: For manageable material at ground level, check throttle response and lubrication between cuts. Do not treat increased response as permission to rush, cut overhead, or remove larger limbs beyond your training.
Takeaway: A sound field test checks cut quality, control, and consistent operation, not just apparent speed.
Maintenance, Sharpening, and Ported-Saw Tuning
A ported saw needs normal chainsaw care plus tuning that suits its modified engine. The stock MS 361 reference is about 2,800 rpm at idle and 13,500 rpm maximum, but those figures do not set a safe limit for a ported saw. Use the builder’s specification and a tachometer for tuning.
Mix fresh gasoline and suitable air-cooled two-stroke oil at 50:1 by volume, unless the saw or oil maker’s instructions say otherwise. Use clean fuel and store it as directed. If the builder specifies a different mix, ask for the reason and confirm it is compatible with the engine and oil.
Do not tune a modified saw to the stock maximum speed by assumption. A tachometer helps measure engine speed, but the correct target must come from the builder or a qualified service professional who understands the porting. Lean or excessive-speed operation can damage an engine. If the saw runs poorly, do not keep adjusting by ear.
Sharpen the chain to its maker’s filing angles and depth-gauge guidance. A dull chain cuts slowly and encourages excess pressure. Do not compensate by lowering depth gauges beyond the stated specification. Replace damaged or stretched chain parts, and inspect the bar groove and sprocket for wear.
Use suitable bar-and-chain oil and check that the chain receives oil. There is no one oil viscosity or flow rate that fits all temperatures, oil types, and pump settings. If lubrication seems weak, stop and inspect the oil supply, ports, and bar before cutting again.
Takeaway: Get the ported saw’s tuning limits in writing and follow the chain maker’s sharpening guidance.
Shutdown, Storage, and Seasonal Care
Shutdown and storage protect both the saw and the next start. Stop the engine and engage the brake before clearing debris or making adjustments. Let the saw cool before refueling or service, then clean and inspect it so damage or a change in condition does not go unnoticed.
After work, clean the air filter as its maker directs, clear the bar groove and oil ports, and remove debris around the sprocket. Check the chain, bar, fasteners, and controls for wear or damage. Record fuel mix, chain changes, and any tuning work; those notes help identify changes over time.
Before storage, follow the saw maker’s fuel and storage instructions. Keep the saw in a dry, secure place, away from children and ignition sources. Do not assume that a ported engine can sit with old fuel without issue. For seasonal care, inspect the fuel system and cutting gear before returning to work.
Takeaway: A short cleaning and inspection routine makes the next field check safer and more useful.
FAQ
Is a ported MS 361 more powerful than a stock saw?
Porting aims to change engine performance, but the result depends on the builder, tune, and saw condition. Without controlled before-and-after measurements, a specific power gain or faster cut time cannot be confirmed.
What bar length should I use?
For routine work, 16–20 inches is a common practical range. Choose a bar that suits the wood, operator, and saw setup. Longer bars need added power and skill; confirm the saw and bar maker’s limits.
What chain fits the MS 361?
The standard pitch is 3/8 inch. Match the chain gauge to the bar, commonly .050 or .063 inch, and match the drive-link count to the bar. Check markings before purchase or installation.
Can I use stock RPM limits to tune a ported saw?
No. About 13,500 rpm is a stock reference, not a safe target for a modified engine. Use the porting builder’s specification and a tachometer, or have a qualified technician tune it.
What fuel mix should I use?
The general mix is 50:1 gasoline to suitable air-cooled two-stroke oil by volume. Follow the saw, oil, and builder instructions, and use fresh fuel.
Is 0.025 inch the right depth-gauge setting?
It is a common reference, not a universal rule. Follow the chain maker’s specification. Excessive depth-gauge lowering can increase kickback and vibration risk.
How can I tell if the chain is getting oil?
Check the oil level and confirm oil reaches the chain during operation, following the maker’s procedure. If the chain or bar runs dry, stop and inspect the oil supply, ports, and pump system.
What should make me stop a field test?
Stop for poor control, a binding bar, a chain that does not oil, unusual noise or heat, surging, or a chain that moves at idle. Diagnose the cause before cutting again.
(This article was written by one of our staff writers, Elliott Fowler. Visit our Meet the Team page.)
