Yamaha F2.5A Owner's Manual

Also see for F25A: Service manual Owner's manual Service manual Service manual Owner's manual

Contents

Installation32the 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 between the bottom of the boat anda level 25 mm (1 in) below it.F2.5AF4B, F5A, F6CNOTICEECM02171 Check that the idle hole stays highenough to keep out water getting insideengine even if the boat is in stationarywith maximum load. Incorrect engine height or obstructionsto the smooth flow of water (such as thedesign or condition of the boat) can cre-ate airborne water spray while the boatis cruising. If the motor is operated con-tinuously in the presence of airbornewater spray, enough water could enterthe engine through the intake openingon the top cowling to cause severe en-gine damage. Eliminate the cause of theairborne water spray.TIP: The optimum mounting height of the out-board motor is affected by the boat andmotor combination and the desired use.Test runs at different heights can help de-termine the optimum mounting height.Consult your Yamaha dealer or boat man-ufacturer for further information on deter-mining the proper mounting height. For instructions on setting the trim angle ofthe outboard motor, see page 51.EMU39753Clamping the outboard motor1. Place the outboard motor on the tran-som so that it is positioned as close tothe center as possible. Tighten the clampscrews evenly and securely. Occasional-ly check the clamp screws for tightnessduring operation of the outboard motorbecause they could become loose dueto engine vibration. WARNING! Looseclamp screws could allow the out-board motor to fall off or move on thetransom. This could cause loss ofcontrol and serious injury. Make surethe clamp screws are tightened se-curely. Occasionally check the screwsfor tightness during operation. [EWM00643]1. Idle hole2. Anti-cavitation plate1. Idle hole2. Anti-cavitation plate0–25mm(0–1in)21ZMU07370ZMU067960-25 mm(0-1 in) 21