How to Tune an Outboard Motor
Proper compression, fuel and spark play the major roles in outboard engine performance. Outboard engines do not get the chance to coast like automobile engines; outboard motors run under load almost all of the time, putting great stress on the ignition system components, pistons, rod bearings, rings and valves. Many outboard motors are stored seasonally and lie dormant for extended periods of time. Tuning the outboard motor for optimum performance will ensure reliable engine performance and trouble-free starting.
Activate the ignition cutoff switch and remove the key from the ignition. Remove the top engine case cowl to your outboard, by unclasping the case snaps. Set the cowl case aside. Place a flywheel strap around the outer rim of the flywheel and pull it taunt. Use a socket and wrench to loosen the flywheel nut.
Place a flywheel puller over the flywheel and set the puller gasping hooks into the flywheel holes. Turn the flywheel puller bolt clockwise with a socket until the flywheel loosens from the shaft. Pull off the flywheel. Remove the ignition points case with a screwdriver. Pull the condenser wire, or wires, from the spring clip. Remove the two screws holding down the points. Remove two more screws, if equipped with dual points. Loosen each condenser screw with a screwdriver and pull out the condensers.
Place the two new condensers in their mounts and tighten their mounting screws with a screwdriver. Set the new points on the base plate, then insert the screws and tighten them only enough to allow the points to swivel open and closed. Rotate the flywheel shaft until the high part of the shaft lobe touches the rubbing block on the points. Place a feeler gauge between the contact points and use a screwdriver to open or close the points by turning the screwdriver inside the adjustment slot.
Refer to your owner's manual for the correct gap measurement for your points. Place the proper width feeler gauge between the contact points, so it moves up and down with some drag. Tighten both points screws. Perform the same procedure on a second set of points. Remember to rotate the flywheel shaft so the second set of points open, then slip the feeler gauge between the contacts for the proper gap. Tighten both screws with the screwdriver. Replace the ignition points cap and tighten it down with a screwdriver.
Place the flywheel over the flywheel shaft. Replace the flywheel nut. Hold the flywheel still with the flywheel strap and torque the flywheel nut down to manufacturer's specifications, according to your engine repair manual.