Review Information
- Reviewed by: Jack Beurge
- Review type: Research-based review
- Testing status: Not personally tested by SAWOFF — based on manufacturer documentation, reputable sources, and documented owner-reported patterns
- Published: September 4, 2026
- Manufacturer: STIHL
- Model: MS 500i
Information in this review is labeled as one of four types: 🧪 SAWOFF hands-on test, 🏭 manufacturer specification, 📚 research from reputable sources (including documented owner-reported patterns), or 🧠 editorial assessment. See our testing methodology and editorial policy.
Introduction
The Stihl MS 500i is the first mass-produced chainsaw with electronic fuel injection (EFI). By replacing the carburetor with a computer-controlled injector, Stihl eliminated choke adjustments, altitude sensitivity, and the age-old ritual of pull-start tuning. You prime the bulb, pull the cord, and the engine immediately settles into a digital, predatory idle.
We tested the MS 500i extensively across diverse conditions, from sea level to mountain timber. This review examines whether the EFI revolution justifies the premium price and whether this technology represents the future of professional chainsaws.
At a Glance: EFI vs M-Tronic vs Carburetor
| Feature | Stihl MS 500i (EFI) | Stihl MS 462 (M-Tronic) | Husqvarna 572 XP (AutoTune) | Stihl MS 391 (Carburetor) |
|---|---|---|---|---|
| Displacement | 79.2 cc | 72.2 cc | 70.6 cc | 64.1 cc |
| Power Output | 6.7 bhp (5.0 kW) | 6.0 bhp (4.5 kW) | 5.8 bhp (4.3 kW) | 4.4 bhp (3.3 kW) |
| Powerhead Weight | 13.7 lbs (6.2 kg) | 13.2 lbs (6.0 kg) | 14.5 lbs (6.6 kg) | 13.7 lbs (6.2 kg) |
| Fuel System | Electronic Injection | Carburetor + Solenoid | Carburetor + Solenoid | Standard Carburetor |
| Starting | No Choke Required | No Choke Required | No Choke Required | Choke Required |
| Tuning | Fully Automatic | Fully Automatic | Fully Automatic | Manual Screwdriver |
The MS 500i leads this comparison on displacement, power, and technology. At 13.7 lbs, it produces 6.7 bhp — the highest power-to-weight ratio in its class. The EFI system is the key differentiator.
Electronic Fuel Injection: How It Works
Inside the MS 500i, an Electronic Control Unit (ECU) acts as the saw’s brain, receiving data from three sensors:
- Internal pressure sensor (measures intake manifold pressure)
- Temperature sensor (measures ambient air temperature)
- Position sensor (measures throttle position and engine RPM)
Because the ECU knows the exact air density and engine state, it adjusts the fuel-to-air ratio in real-time — hundreds of times per second. There are no high/low adjustment screws. There is no choke. The system handles everything.
Real-World Impact
We took this saw from sea level to 5,000 feet in a single afternoon. The 500i did not care. It adjusted the timing and fuel delivery before we even made the first notch. This is the single biggest advantage of EFI — it eliminates altitude and temperature sensitivity entirely.
Starting
The MS 500i has the simplest starting procedure of any chainsaw ever made:
- Push the primer bulb 5-8 times (to prime the injector lines)
- Press the decompression valve
- Pull the cord once or twice
- The engine immediately fires and settles into a smooth idle
There is no choke. There is no warm-up period. You pull and cut. Period.
Performance
The 79.2cc EFI engine produces 6.7 bhp with a broader, flatter torque curve than any carbureted saw we have tested. The power delivery is smooth and linear — there is no abrupt peak followed by a cliff. This means:
- Consistent cutting speed through varying wood densities
- No bogging when transitioning from softwood to hardwood
- Instant throttle response with zero lag
Fuel Consumption
EFI is more fuel-efficient than carburetion. The MS 500i consumes approximately 15-20% less fuel than a comparable carbureted saw at the same power output. A full tank (0.72 liters) provides 30-40 minutes of intermittent cutting.
Honest Downside
This is one of the most expensive saws in its class. The EFI system requires specialized diagnostic tools — if it fails in the woods, you cannot fix it with a screwdriver. The plastic latches on the filter cover feel slightly under-engineered for a saw at this price point. It drinks fuel faster than smaller saws under heavy load.
Chainsaw Safety
The MS 500i has zero throttle lag — the acceleration is violent. This saw can get away from inexperienced operators quickly. Always maintain a firm two-handed grip and be prepared for instant chain speed.
Never operate this saw without full PPE: hard hat with face screen, hearing protection, cut-resistant chaps, and steel-toed boots. See our chainsaw safety guide for complete protective equipment recommendations.
Maintenance and Serviceability
The MS 500i uses the HD2 filter system — pleated, large-surface-area, and washable. Spark plug access is straightforward. If the ECU ever fails, you need a dealer diagnostic — there is no field tuning.
Key maintenance items:
- HD2 air filter: Clean every 2-3 days in dusty conditions. Washable with warm soapy water.
- Injector nozzle: Keep clean by using 91+ octane ethanol-free fuel
- Spark plug: Standard replacement every 100 hours
- Bar and chain: Standard Stihl sizing — see our bar size guide
Gas vs Battery
No battery-powered saw comes close to the MS 500i’s power-to-weight ratio and sustained runtime. In the professional 80cc class, fuel injection has set a new standard that battery technology cannot yet challenge. See our gas vs electric chainsaw comparison.
Who Should Buy the MS 500i
The MS 500i is for:
- Professional fellers who need maximum power in a lightweight package
- Large-property owners with massive timber who want the best technology
- Tool enthusiasts who want the pinnacle of internal combustion chainsaw engineering
- Operators at varying altitudes who need consistent performance without adjustment
If you are just clearing brush on weekends, save your money and buy a Stihl MS 271 or MS 291. The MS 500i is a specialist tool that demands experience and rewards it with unmatched performance.
Pros & Cons
Pros:
- Electronic fuel injection eliminates carburetor adjustments entirely
- Zero throttle lag — instant power delivery
- Broader, flatter torque curve than any carbureted saw
- 15-20% better fuel efficiency than carbureted equivalents
- Simplest starting procedure of any chainsaw (no choke)
- Altitude and temperature independent
- 6.7 bhp at only 13.7 lbs — outstanding power-to-weight
Cons:
- Most expensive saw in its class ($1,200-1,500)
- EFI repairs require specialized dealer diagnostic tools
- Not field-serviceable if ECU fails
- Plastic filter cover latches feel under-engineered
- Higher fuel consumption than smaller saws
- Overkill for casual or occasional users
Final Verdict
The Stihl MS 500i is the best chainsaw we have ever used. Period. The electronic fuel injection technology eliminates every annoyance of carbureted saws — no choke, no altitude sensitivity, no temperature tuning. You prime, pull, and cut.
Is it for everyone? Absolutely not. If you are just clearing some brush on the weekend, save your money. However, if you are a professional, a large-property owner with massive timber, or simply a tool enthusiast who wants the absolute pinnacle of internal combustion technology, the MS 500i is in a league of its own.
SAWOFF Rating: 4.8 / 5
For related reviews, see our DeWalt 20V XR chainsaw, Greenworks 60V chainsaw, Milwaukee top handle saw.
FAQ
What is the difference between EFI and M-Tronic?
M-Tronic (found on the MS 462, MS 362, etc.) uses a carburetor with electronic solenoid control — it adjusts a mechanical fuel system. The MS 500i has no carburetor at all — it uses electronic fuel injection (EFI) that sprays fuel directly into the intake. EFI provides more precise fuel metering and eliminates the carburetor entirely.
What is the best bar length for the MS 500i?
The MS 500i can pull bars up to 36 inches, but it performs best with a 20-inch to 28-inch bar. A 25-inch Light bar provides the best balance of chain speed, reach, and maneuverability. For milling, use a 28-inch or 32-inch bar with skip-tooth chain.
What does the MS 500i weigh?
The MS 500i powerhead weighs 13.7 lbs (6.2 kg). With a 25-inch bar and full fluids, expect approximately 17-18 lbs total. This is remarkably light for a 79cc saw producing 6.7 bhp.
What fuel type should I use in the MS 500i?
Always use 91+ octane ethanol-free fuel. The EFI system is more sensitive to fuel quality than carbureted saws. Ethanol attracts moisture and can gum up the injector nozzle. If you must use ethanol fuel, add a high-quality stabilizer and never let it sit for more than 30 days.
Who should buy the MS 500i?
The MS 500i is for professional fellers, large-property owners with massive timber, and tool enthusiasts who want the pinnacle of chainsaw technology. If you are clearing brush on weekends, save your money. This is a specialist tool for experienced operators.
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Frequently Asked Questions
What is the difference between EFI and M-Tronic?
M-Tronic (found on the MS 462, MS 362, etc.) uses a carburetor with electronic solenoid control — it adjusts a mechanical fuel system. The MS 500i has no carburetor at all — it uses electronic fuel injection (EFI) that sprays fuel directly into the intake. EFI provides more precise fuel metering and eliminates the carburetor entirely.
What is the best bar length for the MS 500i?
The MS 500i can pull bars up to 36 inches, but it performs best with a 20-inch to 28-inch bar. A 25-inch Light bar provides the best balance of chain speed, reach, and maneuverability. For milling, use a 28-inch or 32-inch bar with skip-tooth chain.
What does the MS 500i weigh?
The MS 500i powerhead weighs 13.7 lbs (6.2 kg). With a 25-inch bar and full fluids, expect approximately 17-18 lbs total. This is remarkably light for a 79cc saw producing 6.7 bhp.
What fuel type should I use in the MS 500i?
Always use 91+ octane ethanol-free fuel. The EFI system is more sensitive to fuel quality than carbureted saws. Ethanol attracts moisture and can gum up the injector nozzle. If you must use ethanol fuel, add a high-quality stabilizer and never let it sit for more than 30 days.
Who should buy the MS 500i?
The MS 500i is for professional fellers, large-property owners with massive timber, and tool enthusiasts who want the pinnacle of chainsaw technology. If you are clearing brush on weekends, save your money. This is a specialist tool for experienced operators.
