Trade-A-Boat – April 2018

torquing

talk

WITH ANDREW NORTON

sweet little fifteen

NO PEERS FOR PERFORMANCE AND FUEL EFFICIENCY...

W

hen

Yamaha

Motor

Australia

lent me

a 15F back in 1996, it was

the beginning of a beautiful

friendship. The combination

of a well-balanced power

head, excellent fuel eiciency

and relatively low pollution

on its 100:1 fuel/oil mix won

me over from the start.

Released to the Oz market

in 1995, the 15F replaced the

15D that was immensely

popular among commercial

net fishermen on Lake

Macquarie, NSW, from the

time it was introduced in

1983. The 100:1 fuel/oil mix
      reduced operating costs, as
      did the loop-charged power
      head that used up to 20
      percentlessfuelthanthe
      US-made competition. When
      idling the 15D would tick over
      with scarcely any vibration
      yet had plenty of grunt to
      push the 5.5m round bilge
      semi-planing Asquith LFB
      that was popular at the time.
      I owned an Asquith for
      threeyearsandtheloan
      15D had Yamaha’s clever
      dual-thrust prop that not
      only efectively transformed
      engine torque to thrust at the
      prop but also gave incredible
      stopping power compared
      to standard through-hub

exhaust props. On the easily-

driven Asquith the 15D would

cruise all day at 10-11kts with

the engine using 3lt/h while

pushing a total of 600kg.

Yamaha took that

wonderful power head and

fitted it in an outboard that

was specifically designed

to compete with the US

competition. Features such

as the unique cold-start

system and upfront gear

shift also made the 15F much

nicer to use on a daily basis

than the 15D. And a fold-

up carry handle simplified

lugging the engine around

when taking it to a dealer

for servicing. The rounded

cowl and engine pan actually

made the 15F look smaller

than the angular 15D even

though overall dimensions

were similar.

THE NITTY GRITTY

Alongwithitsde-rated

9.9 counterpart, the 15F

is Yamaha’s smallest

displacement twin-cylinder

loop-charged power head and

features an easily replaced

thermostat plus the ability to

fit oversize pistons and rings

after reboring the cylinders.

A dry exhaust relief

efectively baes noise

making the 15F the quietest

two-stroke 15 available.

Mechanical ignition

timing advance linkages

connect directly with the

cold-start system and a

multi-position choke knob.

Pull the knob one stop and

the choke butterfly valve

flap is partially closed. Stop

two advances the ignition

slightly, while stop three

alsoopensthethrottle.The

result is positive cold starting

without the complication of a

fuel primer that can be prone

to blockages.

A bowl-type fuel filter

makes filter cleaning easy,

while spark plug access is

excellent. However the four-

position trim adjustment

isalittlearchaic,butat

leasttherearetwoshallow-

water drive settings. A strut

support system is used

for the full tilt lock and

steering, and throttle friction

adjusters are fitted. A 12V

80W alternator is fitted with

provision for connecting to a

rectifier for battery charging,

though as the output is

unregulated a battery of

at least 40amp/h should

be used to prevent “frying”

on long runs to and from a

favourite fishing spot.

The break-in period is

10 hours on 25:1 before

switching to the normal 100:1.

Servicing intervals are

every 100 hours or annually

after the first 20 hours

or three months. Regular

maintenance is easy with

one example being the

handpump for the gear oil

that attaches to a Yamalube

oil container. Simply screw

in the pump nozzle to the oil

drain hole, pump until fresh

lube dribbles from the oil

vent hole, screw in the vent

plug, remove the fill nozzle

“I sold the engine, which was bought by

the first person who saw it for the price

asked. No doubt about Yamahas, they

have excellent resale value”

130 tradeaboat.com.au