LEHR 2.5 HP 4-STROKE - Manual (Page 9)

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INSTALLATION
INSTALLATION
Incorrect engine height or obstructions to smooth water flow in front of the propeller can cause propeller
cavitation while the boat is cruising. Cavitation occurs when the engine speeds up momentarily and suddenly
slows as the propeller engages the water. Severe engine damage may result if the motor is operated
continuously while cavitating. During water testing check the buoyancy of the boat, at rest, with its maximum
load. Check that the static water level on the exhaust housing is low enough to prevent water entry in to the
power head, when water rises due to waves when the outboard is not running.
MOUNTING THE OUTBOARD MOTOR
• Overpowering a boat could cause severe instability. Do not install an outboard motor with more horsepower
than the maximum rating on the capacity plate of the boat. If the boat does not have a capacity plate,
consult the boat manufacturer.
• This section is intended as reference only. It is not possible to provide complete instructions for every
possible boat and motor combination. Proper mounting depends in part on experience and the specific boat
and motor combination. Improper mounting of the outboard motor could result in hazardous conditions, or
poor handling, loss of control, or boat damage.
• Your dealer or other person experienced in proper out board motor mountings should show you how to
mount your motor. Mount the outboard motor on the center line (keel line) of the boat, and ensure that the
boat itself is well balanced. Otherwise the boat will be hard to steer. For boats without a keel or which are
asymmetrical, consult your dealer.
MOUNTING HEIGHT
To run your boat at best efficiency, the water resistance (drag) of the boat and outboard motor must be
made as little as possible. The mounting height of the outboard motor greatly affects the water resistance.
If the mounting height is too high, cavitation tends to occur, thus reducing the propulsion, and if the propeller
tips cut the air, the engine speed will rise abnormally and cause the engine to over heat. If the mounting
height is too low, the water resistance will increase and thereby reduce engine efficiency. Mount the
outboard motor so that the anti-cavitation plate is between the bottom of the boat and a level 25mm (1in.)
below it.
The optimum mounting height of the outboard motor is affected by the boat and motor combination and the
desired use. Test runs at different heights can help determine the optimum mounting height. Consult your
boat manufacturer for further information on determining the proper mounting height.
CLAMPING THE OUTBOARD MOTOR
1. Place the outboard motor on the transom so that it is positioned as close to the center as possible. Tighten
the transom clamp screws evenly and securely. Occasionally check the clamp screws for tightness during
operation of the outboard motor because they could become loose due to engine vibration.
WARNING: Loose clamp screws could allow the outboard motor to fall off or move on the transom. This could
cause loss of control and serious injury. Make sure the transom screws are tightened securely.
Occasionally check the screws for tightness during operation.
CENTER LINE
(KEEL LINE)
a a
ANTI-CAVITATION PLATE
RESTRAINT CABLE
2. If an engine restraint cable or chain attachment is equipped on your boat, the cable or chain should be
used. Attach one end of the engine restraint cable attachment to the engine clamp and the other to a
secure mounting point on the boat. Otherwise the engine could be completely lost if it accidentally falls
off the transom.