The 50cc class is the sweet spot where power meets portability. The Husqvarna 550 XP Mark II is not just a minor updateâit was a ground-up redesign addressing the heat-soak issues of the original. With a magnesium crankcase, AutoTune 3.0, and RevBoost technology, this is a professional saw built for arborists and foresters who need to produce all day.
Quick Comparison: The 50cc Pro Hierarchy
| Model | Displacement | Power Output | Weight |
|---|---|---|---|
| Husqvarna 550 XP MK II | 50.1cc | 4.0 hp | 11.7 lbs |
| Stihl MS 261 C-M | 50.2cc | 4.0 hp | 10.8 lbs |
| Echo CS-490 | 50.2cc | 2.14 hp | 10.6 lbs |
| Husqvarna 450 | 50.2cc | 3.2 hp | 11.2 lbs |
Engineering Deep-Dive
The X-Torq engine uses a pure air barrier to scavenge exhaust, delivering a flat torque curve that sounds more like a 60cc saw under load. The cooling fins and flywheel were redesigned for the Mark II to prevent the heat soak that plagued the Gen 1 saws.
AutoTune 3.0 monitors engine temperature, fuel quality, and altitude, adjusting the solenoid valve ten times per second. Our key advice: The warm-start issues of the original 550 XP are virtually eliminated. The Mark II fires on the first half-pull every time, regardless of temperature.
For more on power source decisions, see gas vs electric chainsaw.
Real-World Performance
The RevBoost technology provides instant chain speed for limbingâthere is zero hesitation when you blip the trigger. In 16-inch logs, the 550 XP showed zero fatigue. The lugging power is real; this saw has a broader power band than the legendary 346XP.
Ergonomics and Operator Comfort
The handle spacing is optimized for neutral wrist position. At 11.7 lbs, the weight is centered so well it feels lighter in motion. The LowVib steel springs provide consistent damping without the degradation rubber bushings suffer over time.
Maintenance and Serviceability
Captive bar nuts cannot be lost in the field. The Snap-lock top cover provides instant access to spark plug, air filter, and cylinder fins. The fuel window lets you check levels without opening the tank. The adjustable oil pump allows dial-in for different bar lengths. Maintenance checklist: Clean Air Injection fins every 20 hours, check spark plug annually, and always use ethanol-free fuel.
Verify your bar and chain match your model.
Chainsaw Safety
Read our chainsaw safety guide before operating. The 550 XP is a high-performance pro sawârespect its power and wear full PPE.
Pros and Cons
Pros: Insane RevBoost throttle response; magnesium crankcase for 1,000+ hour lifespan; AutoTune 3.0 works flawlessly across altitudes; redesigned cooling system eliminates heat issues; captive bar nuts.
Cons: About a pound heavier than Stihl MS 261; premium pro pricing; air filter cover clips stiff in sub-zero temperatures.
Final Verdict
The Husqvarna 550 XP Mark II is one of the finest chainsaws ever manufactured. It is not for the casual homeownerâit is for the professional who treats their tools like an extension of their body. The way this saw screams through a cut is addictive.
SAWOFF Rating: 4.8 / 5
Get out there and cut. Safely.
Frequently Asked Questions
What is the best fuel mix for the Husqvarna 550 XP?
A 50:1 ratio using high-quality synthetic oil like Husqvarna XP+ or Stihl HP Ultra. Use ethanol-free 91+ octane fuelâethanol is the silent killer of AutoTune solenoids and rubber fuel lines.
Can I run a 20-inch bar on the 550 XP?
Yes, the 550 XP has the torque to handle 20 inches in most softwoods and medium hardwoods. However, the sweet spot is an 18-inch bar for balance and chain speed.
My 550 XP is hard to start when hot. What should I do?
On the Mark II this is rare. Try setting the choke (which sets high idle) and immediately pushing it back in before pulling. This half-throttle setting gives AutoTune the best chance to prime.
How often should I clean the air filter?
For a pro user, check once a week. The Air Injection system does most of the work. Never use compressed airâtap gently or wash with warm soapy water.
What is the difference between the 550 XP and the 545 Mark II?
They share the same chassis. The 550 XP is tuned for higher RPMs with RevBoost for faster acceleration. The 545 is a pro-sumer version with less aggressive tuning.
Does the 550 XP Mark II have a decompression valve?
Yes, located on top of the cylinder. Depress it before every cold or hot start to reduce wear on the starter recoil mechanism.
Why is my AutoTune saw running poorly after changing the air filter?
AutoTune needs a few minutes to re-learn the new airflow. After maintenance, let it idle for a minute, then make several full-throttle cuts to recalibrate.
What is the power output of the 550 XP MK II?
The 50.1cc X-Torq engine produces 4.0 hp (3.0 kW) at 10,200 rpm, making it one of the most powerful saws in the 50cc professional class.
