2018 Yamaha F90 Midrange Mechanical 20 F90LB Outboard Motor

At 1.8 liters, the 2018 Yamaha F90 Midrange Mechanical (model code F90LB) carries Yamaha's largest single-overhead-camshaft block in this family, four valves per cylinder, and a weight cut of 13 lbs versus the previous 90 hp design.

Rigging checks

Remote mechanical steering means the matching cable and control box need to already be in place. Dry weight is 353 lbs, and this block runs fine in fresh water or salt.

Charging and electronics

Three-phase alternators put out up to 35 amps, 40 percent more than the previous design at this size, which covers Yamaha's Multi-Function Tiller Handle and Command Link gauges with room to spare. An air silencer box and surge tank cut intake noise and turbulence at cruise.

Running it

The Variable Trolling RPM Switch lets idle settle anywhere from 550 to 1000 rpm, adjustable in 50-rpm steps. Trim moves from -4 to +16 degrees, tilt climbs to 70 degrees, and the oil fill takes 3.2 liters with a filter fitted or 3 liters bare. The engine warning system automatically pulls maximum rpm down to 2000 if it senses trouble.

What is the full-throttle ceiling? Roughly 6000 rpm. What protects the block from corrosion? A proprietary alloy under a five-layer anti-corrosive paint process. Is this the standard shaft length? Yes, this listing is the shorter-shaft F90LB; Yamaha also builds a longer-shaft F90XB for taller transoms.