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NEW YAMAHA FOUR-STROKES

Yamaha recently launched a pair of new four-stroke outboards for the 2014 season and both are venturing into new waters sharing the common theme of lighter, stronger, faster and more fuel-efficient, all while retaining Yamaha’s proven reliability. These mid-sized newbies are the F115B and the F175, so let’s get right into the nuts and bolts and see what makes these four-strokes tick.
By Capt. John N. Raguso
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NEW YAMAHA FOUR-STROKES

YAMAHA F115B
The newly redesigned F115 outboard is not only more powerful and compact compared to its predecessor, but is currently the lightest outboard in the 115 horsepower four-stroke class. Tipping the scales at a svelte 377-lbs, the new F115B is 24-lbs lighter than the previous generation (F115LA) Yamaha. Weight savings are derived from a variety of new materials, such as a composite lower pan and cowling, a single ram power trim and tilt mechanism and a new lightweight mounting bracket. The F115’s all-new powerhead provides increased bore and stroke, which now measures a full 1.8-liters. The outboard’s double-overhead cam (DOHC) four-cylinder design now has larger intake and exhaust valves for easier breathing, more power and better midrange torque.

Complementing the new valves and cylinder head is a new 60mm single-throttle body with Yamaha’s long-intake track system and a new free-flow exhaust manifold. Compression ratio is increased, and so is the full-throttle rpm range (5,300 to 6,300 rpm). A knock sensor allows the engine to operate constantly at peak output, with faster acceleration than its predecessor. The new alternator delivers more power than before, with 35 amps at wide open throttle (compared to 24 amps for the previous F115), producing a full 28 amps at only 1000 rpm.

The new F115 model is mechanically controlled and compatible with Yamaha’s Command Link gauges and hardware as well as the Y-COP theft deterrent system. To help mitigate corrosion, the F115 uses Yamaha’s Phaze Five paint system, which involves the electro-deposition of anti-corrosive paint on both the outside and inside passages of the engine block. The F115B also includes Yamaha’s Variable Trolling RPM Switch (VTS) and can be equipped with Yamaha’s Multifunction Tiller Handle. Available in both right-hand and left-hand rotation, the F115B is perfect for both single and twin applications and is expected to begin shipping in the second quarter of 2014.

YAMAHA F175
Hot on the prop exhaust of the recently introduced in-line four cylinder F200 is yet another sibling that’s based on the same 2.8-liter platform, the new F175. Initially I thought that this new girl might be a detuned F200 that runs on 87-octane gasoline, but Yamaha’s Communications Manager Martin Peters corrected my misconception and provided some additional mechanical and design parameter insights. According to Martin, “There’s a little more to it than that. If you look at the specifications carefully, you will see there are a couple of key differences between the two motors. The F175 and F200 are built on the same platform, but they are not the same powerhead. The F200 uses Variable Camshaft Timing (VCT), while the F175 does not. Also, the F175 is not available with counter rotation, plus it is mechanical only.”

Some of the key selling features of the F175 are its relatively light weight (483-lbs), naturally aspirated EFI powerhead and simple mechanical design that is engineered to run on 87-octane fuel. It looks like a real winner for those single engine bay and coastal center consoles that need to repower, but have transom horsepower and/or weight limitations that can't mount a 200 or a V-6 engine.

The F175’s 2.8-liter, four-cylinder 16-valve dual overhead camshaft (DOHC) powerhead breathes easily and responds quickly, with a sophisticated valve train design that’s been proven by millions of hours of use. The F175 also uses a single-throttle intake valve and Yamaha’s long-track intake tubes for easy breathing. A knock sensor allows the engine to run at peak efficiency and performance at all rpm. With electrical output of 50 amps, the F175 provides plenty of power to keep your boat’s marine electronics humming. The outboard is mechanically remote controlled for easy rigging and is compatible with Yamaha’s Command Link gauges and the Y-COP theft deterrent system, with a convenient Variable Trolling RPM Switch (VTS). The Phaze Five paint systems helps control corrosion and like its smaller sister, the F175 will begin shipping sometime in Q2 of this year.

Yamaha’s Reliance SDS (shift dampening system) propellers are ideally suited for use with Yamaha’s new Yamaha F175 outboard and are CAD/CAM designed to optimize the performance of large displacement, in-line four-cylinder engines. Reliance SDS propellers are available in 15-inch, 17, 18, 19, and 21-inch pitches.

Both of these new outboards are backed by a three-year parts and labor warranty.