Small Portable Outboard Care (2.5 to 20 hp Kickers and Dinghy Motors)

Mercury's advice for clamp-on motors: back the clamp screws all the way out, hang the motor centered on the transom, then tighten the two screws a little at a time, alternating, until they're very tight, and finish with the handles roughly horizontal. A padlock through both handles deters theft and stops the screws from vibrating loose. Many owners also tie a short safety line from the motor to the boat so a loose motor can't sink. Mercury adds that on most boats the anti-ventilation plate should sit an inch or two below the bottom of the hull; if not, ask a dealer whether the shaft length is right.

Southern Boating notes that motors of about 25 hp and under are the ones that most often end up on the bottom, usually because clamp screws vibrated loose or someone tripped carrying one down the dock. Recheck the clamp screws during the day. If it does go overboard: don't try to start it. Rinse it with plenty of fresh water (after salt water, keep it submerged in fresh water if you can't get it to a shop right away) and get it to a technician the same day. The water in engine oil guide has more detail.

Old gas is the number-one reason small outboards won't start. Cruising World warns that ethanol-blended fuel sitting much longer than about 90 days can cause real trouble, even with stabilizer. Buy small amounts, add the stabilizer your engine maker approves at the label dose, and use ethanol-free fuel if you can find it. On a two-stroke, mix oil at exactly the ratio in your manual, in a separate can, never by guessing in the tank.

• Four-stroke oil: with the motor upright, check the dipstick. Low oil or oil that looks milky or smells of gas needs attention before you run it.
• Fuel vent: open the tank vent (built-in tanks and most portable tanks have one) or the motor will starve and die after a few minutes.
• Kill switch: clip the lanyard to yourself; most small motors won't start without it.
• Fuel line: check the hose and primer bulb for cracks and leaks.

After starting, look for a steady stream of water from the small telltale outlet on the motor's leg or cowl. No stream, or a weak, spitting one, means stop the motor and check for a blocked intake or telltale, or a worn water pump impeller. Small motors overheat quickly. Yamaha points out that mud daubers and other insects love to nest in the telltale outlet of a motor that has been sitting, so poke the outlet clear with a bit of wire or a small zip tie before you suspect the pump. It also notes some motors only show a stream once the rpm comes up a little; if yours doesn't, watch for the overheat warning.

Salt, silt and sand build up in the cooling passages. Yamaha says regular freshwater flushing goes a long way toward extending an outboard's life, especially in salt water. On small motors the simplest way is to clamp the motor to a sturdy stand or a sawhorse with the lower unit in a large bucket or trash can of fresh water deep enough to cover the intake, then idle it for a few minutes with the prop removed. External flush muffs over the intake also work for running the engine. If your motor has a built-in flush port, use it only to flush with the engine off, unless your owner's manual explicitly says the engine may run on the port. Yamaha's rules apply whenever the engine is running:

• Turn the water on (or fill the bucket) before starting, and only shut the water off after the engine stops.
• Idle only. Don't rev on muffs; there isn't enough water flow at high rpm.
• Keep the water intake screens clean.

Fuel left sitting in a small carburetor turns to varnish and blocks its tiny jets. Before transport and before any break of more than a few weeks, empty it. Mercury's procedure for its portables:

• With the lower unit in water, start the motor.
• On a built-in tank model, close the fuel valve; on a remote tank model, disconnect the fuel line.
• Let it run until it stops by itself.
• Close the tank vent (built-in tank), or put the protective cap on the fuel connector (remote tank). Many carburetors also have a small drain screw on the float bowl. Opening it over a rag gets out the last bit of fuel. Check your manual for its location and close it again afterward.

Mercury warns that laying a portable outboard on the wrong side lets oil drain out of the crankcase and into the cylinders, which can damage the engine. Before you carry it:

• Hold it upright for a minute after flushing so water drains out of the leg.
• Transport it upright on a stand or bracket when you can. If it must lie down, follow the sticker or the manual: correct side up, resting on its pads.
• Some motors are designed to lie on their side safely; Yamaha says its F2.5, F4 and F6 have an oil retention system and resting pads that allow on-side storage. That's model-specific, so don't assume yours can.
• Wrap it in old towels or a blanket and wedge it so it can't slide around, as Mercury suggests.

At least once a season, and any time the motor revs but the boat doesn't move:

• Remove the kill switch clip first so it can't start.
• Take off the prop (usually a cotter pin and a nut, or just a cotter pin on the smallest motors).
• Check the shear pin: a sheared or bent pin must be replaced with the correct part from your maker. Never substitute a bolt or nail; a hard pin passes the shock straight to the gears.
• Look behind the prop for fishing line wrapped around the shaft. It can cut the seal and let water into the gearcase.
• Check the prop blades for dings and cracks, put a light coat of marine grease on the shaft, and reinstall with a new cotter pin.

Cruising World's method: with the motor upright, remove the upper (vent) screw on the gearcase. Oil should be at the hole or just below. Look at a drop of it. Milky or creamy gear oil means water is getting past a seal and needs a mechanic soon. To change it, drain from the bottom screw, then refill from the bottom with the maker's gear oil until it comes out the top hole. Fit new washers on both screws. Details are in the lower unit oil change guide.

Small four-strokes hold very little oil, so it gets dirty fast. Change it at the interval in your manual, and before storage if it's due, with the motor upright and warm. Many small motors have no filter and some drain by tipping the motor; follow your manual exactly and use the oil grade it specifies. Two-strokes skip this step.

• Anodes: Cruising World recommends replacing them once they're about half worn away.
• Grease points: swivel and tilt pivots, clamp screws and the throttle linkage, using the grease your manual names.
• Spark plug: check the color and gap (use the spec in your manual), and replace it if it's worn or fouled.
• Pull cord: replace it if frayed.
• Corrosion: after salt water, wipe the motor down with fresh water and a corrosion protectant on the outside surfaces your manual allows.

• Flush, then run the carb dry (Step 6) or follow your manual's storage procedure, which may include fogging the cylinder.
• Change the four-stroke oil if due and check the gear oil.
• Drain or use up old fuel in the built-in tank, and store fuel cans away from living spaces.
• Store the motor upright on a stand, in a dry place, with the leg lowest so water can't sit in the powerhead. If it must lie down, use only the side the maker allows.
• If it has to winter outdoors on the boat, Yamaha suggests either trimming it fully down or slipping a tightly sealed plastic bag over the gearcase once it's completely dry, so moisture can't collect in the lower unit and freeze. Check the gear oil for water before the season, too.
• Look under the cowl and at the air intake in spring for bird or insect nests before the first start; Yamaha lists this as part of its routine.
• Log the date and what you did in BoatMend.