2017 Tohatsu 20 HP MFS20DEFS Outboard Motor

Where the MFS20DEFL runs a 20-inch shaft, the 2017 Tohatsu MFS20DEFS carries the same 20 hp four-stroke on a 15-inch short shaft, still with tiller steering and electric start. Tohatsu positions it for the same mid-size to larger aluminum boats, skiffs, inflatables, and heavier sailboats, built for transoms that sit lower.

Short shaft fitment

A short shaft only belongs on a boat built for one; mounting a 15-inch shaft where a longer-shaft motor is called for leaves the propeller running shallow and hurts performance. Confirm transom height against Tohatsu's short-shaft spec before ordering rather than guessing from the boat's overall size.

What's standard

This single-carburetor, water-cooled twin-cylinder engine carries a forward, neutral, and reverse shift lever up front, a 3.1-gallon external tank for fuel, and electric start backed by its own alternator. Wide open, the 351cc block climbs toward 6,100 rpm, with the low end of that range sitting at 5,400.

Q: Does the short shaft mean less power? No, output, displacement, and controls are unaffected; only the shaft length and the transom it suits change, so sizing comes down entirely to your boat.

Tohatsu's 5-year warranty applies here, with bore, stroke, and gear ratio shown in the full spec table on this page. Being carbureted rather than fuel-injected, it benefits from a dose of fuel stabilizer before any stretch of storage longer than a few weeks.

Specifications