Stihl MS 500i vs Stihl MS 661 C-M Magnum

Stihl / Gas

Stihl MS 500i

70cc+ class

~$1,780

Stihl / Gas

70cc+ class

~$1,850

The Stihl MS 500i costs about $70 less; the Stihl MS 661 C-M Magnum has more engine (91.1cc); the Stihl MS 500i swings a longer bar (25 in).

Spec	Stihl MS 500i	Stihl MS 661 C-M Magnum
Approx. price	~$1,780with 25" bar and chain	~$1,850with 20" bar and chain
Engine class	70cc+ classby displacement	70cc+ classby displacement
Power type	Gas	Gas
Use case	Professional	Professional
Engine	79.2 cc	91.1 cc
Rated power	5 kW	5.4 kW
Bar length	25 in	20 in
Single-pass cut	about 23 in	about 18 in
Bar range	16-36 in	16-32 in
Chain	3/8" pitch / .050" gauge (33 RS3)	3/8" pitch / .050" gauge (33 RS)
Weight	13.9 lbpowerhead only	16.4 lbpowerhead only, dry (no bar/chain/fuel)
Warranty	1-year consumer / 3-month professional (Stihl policy from Jan 1, 2026)	1-year consumer / 3-month professional (Stihl policy from Jan 1, 2026)

Tinted cells mark the better figure on that row alone: more engine, longer bar, lighter, cheaper. A lighter weight is only a win on the same basis.

Electronic fuel injection — no carburetor at all; starts in 2-3 pulls and auto-adapts to altitude and temperature
5.0 kW from a 13.9 lb powerhead — Stihl claims the best power-to-weight ratio on the market
Instant throttle response owners say no carbureted saw can match
Runs bars from 16" to 36", covering everything from bucking to serious felling
Owner threads report multi-year reliability — 'always starts, never let me down' is the common refrain
Strong resale value; used 500is barely depreciate

Heavy fuel consumption is the most repeated owner complaint — plan on carrying extra mix
Documented gripe about fine dust entering around the plastic air-filter attachment point
Price has climbed roughly $500 since launch to ~$1,780, prompting even fans to hesitate
Some high-hour owners report warm-start stalling quirks after several years
Injection system is dealer-only territory — no backyard carb fixes if the electronics act up

M-Tronic auto-tuning means no carb screws — it compensates for altitude, temperature, and fuel quality on its own
16.4 lb powerhead carrying 7.2 hp is excellent power-to-weight for a 90cc saw
Buries a 28-32 inch bar in hardwood without bogging — the go-to powerhead for Alaskan mills
20% better fuel economy than the old MS 660 it replaced
Decade-plus of forum history with a reputation for surviving years of commercial abuse
Every Stihl dealer can service it, and the parts network is unmatched

Roughly $1,850 before tax — the price has climbed several hundred dollars in a few years
Overkill for most users; MS 462 owners rightly point out theirs is 3 lbs lighter for 90% of the work
Thirsty in sustained cuts — milling users report burning through tanks quickly
Stihl gas-saw warranty is only 1 year consumer / 3 months commercial unless you buy the oil promo
Dealer-only sales, so pricing varies by region and there are no retailer reviews to compare