Operation21motor greatly affects the water resistance. Ifthe mounting height is too high, cavitationtends to occur, thus reducing the propulsion;and if the propeller tips cut the air, the enginespeed will rise abnormally and cause the en-gine to overheat. If the mounting height is toolow, the water resistance will increase andthereby reduce engine efficiency. Mount theoutboard motor so that the anti-cavitationplate is in alignment with the bottom of theboat.NOTE: The optimum mounting height of the out-board motor is affected by the boat/motorcombination and the desired use. Testruns at different heights can help deter-mine the optimum mounting height. Con-sult your Yamaha dealer or boatmanufacturer for further information on de-termining the proper mounting height. For instructions on setting the trim angle ofthe outboard motor, see page 30.EMU26970Clamping the outboard motor1. Place the outboard motor on the tran-som so that it is positioned as close tothe center as possible. Tighten the tran-som clamp screws evenly and securely.Occasionally check the clamp screwsfor tightness during operation of the out-board motor because they could be-come loose due to engine vibration.WARNINGEWM00640Loose clamp screws could allow the out-board motor to fall off or move on thetransom. This could cause loss of controland serious injury. Make sure the tran-som screws are tightened securely. Oc-casionally check the screws for tightnessduring operation.2. If the engine restraint cable attachmentis equipped on your engine, an enginerestraint cable or chain should be used.Attach one end to the engine restraintcable attachment and the other to a se-cure mounting point on the boat. Other-wise the engine could be completely lostif it accidentally falls off the transom.3. Secure the clamp bracket to the transomusing the bolts provided with the out-ZMU01762ZMU02012ZMU02013