2018 Yamaha F4 Portable Tiller F4SMHA Outboard Motor

Yamaha's 2018 F4 Portable Tiller (F4SMHA) uses the short, 15-inch shaft, suited to a shallower transom than the L-shaft version of the same engine. It is a single-cylinder, 139 cc four-stroke rated at 59 lbs dry, with a built-in carrying handle for moving it between boat and storage.

Before you order

Match transom height to the 15-inch shaft, since this short-shaft version sits differently on the hull than Yamaha's longer-shaft F4. Steering friction and the F-N-R shift handle are both tuned for one-hand control from a tiller, and a 5-step trim adjustment pairs with a 3-step shallow water drive for working skinny water close to shore.

Storage and starting

Starting is manual, aided by an easy-grip knob and a decompression mechanism that lightens the pull. The motor can rest on either side or on its front grip without oil leaking out, which matters if it moves on and off a boat often. An auxiliary priming pump built into the fuel line helps it restart smoothly after sitting unused, and a tilted, water-resistant fuel filler cap plus a built-in fuel strainer keep the 1.1-liter see-through tank running clean. 87-octane regular unleaded keeps it running, with an oil capacity of about six-tenths of a liter, and an optional kit adds a 6-amp alternator for small electronics.

What is the compression ratio? 8.9:1, run through an overhead-valve, carbureted induction system cooled by raw water with thermostatic control. What is the top rpm at full throttle? Around 5000 rpm.

Specifications