Stihl MS 251 Wood Boss

The drill gets posted every time. Flip the saw to the run position — not high idle, not choke — make sure the ignition is on, hold the trigger at full throttle, pin the powerhead down securely with a knee and pull it over twenty to thirty times. That pushes a great deal of air and almost no fuel through the cylinder and clears it; be ready for the saw to actually fire somewhere around a dozen pulls in. The prevention is the part owners stress hardest: the 250 and 251 flood extremely easily, so never pull more than three times on full choke, and switch to half choke the moment it burps.

Owners say no, repeatedly and without much patience. Eighteen inches is the ceiling and several argue even that costs you noticeable cutting speed; one who asked about a 24-inch bar with a skip chain for a handful of big trees was told flatly that if he wants to run a 25-inch bar he needs an MS 400 or larger. The people who run 18 inches successfully — including the pair who cut hickory and oak for two decades — pair it with a sharp full-chisel chain and accept taking their time in dense wood. Anyone bucking 25-inch hardwood with it reports the saw really struggling.

Several owners describe exactly this, including one whose bar got hot enough to burn the embossed markings off while the oiler appeared to be working. The pattern worth checking is the one two owners both hit: the oiler visibly squirts plenty with the bar removed, but oil never reaches the bar once it is mounted — so look at the oil port alignment and the bar's oil hole, not just the pump. One owner found thick black oil dribbling out and seeping around the sprocket cover instead of throwing a spray, and a full teardown and clean did not fix it. Chain tension and bar condition matter too: owners point to burrs on the bar rails, which widen the bar beyond the chain and create drag, and recommend dressing them flat with a file.

A former dealer mechanic who worked on both says yes and gives two reasons. The 250's air filter is a clip-on felt type notorious for not sealing properly and letting debris past, while the 251 uses a pleated canister that twists on a quarter turn. And the 251 dropped the 250's quick-adjust bar with the delicate moulded plastic hook that effectively totalled the saw when it broke. Technically the 251 is a strato design with about 20% better fuel economy; the 250 breathes more freely, which is why some old hands still prefer it, but owners say the difference in the cut is hard to feel unless you are very experienced.

It is at the edge. Owners cutting two to four cords report years of service on filters, plugs and chains. Past that the complaints change tone: one owner doing a lot of cutting with eight trees waiting said the saw simply lacks power and went shopping with a $1,500 budget; another found 25-inch birch a struggle. The answer owners give most often is to keep the 251 as the small saw and add 10cc or more above it, and the saw they name is the MS 261 — same ballpark weight, magnesium case, noticeably more torque so it does not bog. The Echo CS-590 comes up just as often as the cheaper route to the same capability.

The factory setup is .325 pitch on .063 gauge with Stihl's green safety chain, and owners' first move is usually to get the dealer to swap to the yellow full-chisel chain, which cuts faster but dulls quicker and is less tolerant of dirt — semi-chisel is the better choice if your wood is dirty. Keeping at least two sharp spare chains and a spare bar is advice that comes up in nearly every thread about this saw, because a bound bar ends your day otherwise. Owners who want more speed convert to 3/8 pitch with a 7-tooth rim sprocket and describe the result as a different saw; third-party .043-gauge 3/8 low-profile chains exist for anyone who does not want safety chain at all.