2017 Yamaha F9.9 F9.9SMHB Outboard Motor

At 15 inches, the shaft on this 2017 Yamaha F9.9 F9.9SMHB is the shortest offered for the 9.9 hp twin-cylinder portable, and at 87 lbs dry it is also the lightest of the three shaft lengths Yamaha sells under the F9.9 name.

Confirming the shaft

This same F9.9 is also sold on longer shafts that will not fit a shorter transom correctly, so measure against this 15-inch figure first. Steering travels 43 degrees off-center each way, tilt reaches 71 degrees across 4 positions, and mounting centers are spaced 28.6 inches.

What's under the cowling

Bore and stroke measure 2.48 and 2.29 inches, with compression at 9.46:1. Either a pull cord or the electric button gets it started, though the 6-amp alternator still needs an external rectifier and regulator before it can top off a battery. 87 octane regular unleaded covers fuel needs, with the oil fill landing near 0.8 liters, ethanol capped at 10 percent, and the rev range climbing to roughly 6000 rpm. Mounting hardware and the gearcase carry over from the other two F9.9 shaft lengths.

What emissions rating does it carry? A 3-star C.A.R.B. rating. What spark plug does it use? A BR6HS. Is the housing interchangeable with the other shaft lengths? No, each F9.9 shaft length has its own housing; match the 15-inch figure here to the boat before ordering rather than assuming it fits every transom.