Wiring

Check all engine wiring for brittle insulation or fraying. This would necessitate re-wiring or installation of a new wiring harness, particularly in the case of SoC. In an emergency, liquid, brush-on insulation can be used. Replace high tension wires with ones recommended in the manual; i.e. replace carbon core wires with carbon core wires, stranded wires with stranded….

Clean and inspect battery connections. The number one reason for low cranking speeds is poor contact at the battery and starter solenoid ends of the cables.

Spark

Pull the plug wires from the sparkplugs. Your spark should jump a minimum of a 3/8" gap with a hot thick spark. If it doesn’t, you need maintenance on the ignition system. DO NOT crank the engine unless there is a path for the electricity to go to ground. Failing to do so may result in internal arcing in the coil, switch or CD box, leading to eventual ignition failure.

Check the sparkplug cables for cracked insulation. Otherwise, the needed maintenance will be determined by type and year of motor you’re working on. Refer to your manual.

Replace the spark plugs with the manufacturer's recommended plugs, keeping the old ones as spares. Set the gap per your owner’s manual requirements.

Almost all coils made from the 50s to late 60s will crack and leak at sometime in their (short) lifespan. If your motor has never had the coils replaced, the odds are it will now.

Breaker Points

When points-equipped engines sit for a long time, the points may ‘frost’ over with a thin coating of oxidization or grease. This is most likely to happen if the motor is stored where humidity and temperature are not controlled, such as a garage.

If so equipped, remove the recoil start to gain access to the flywheel. Remove the flywheel nut. Often a strap wrench will be required to hold the flywheel while loosening the nut. DO NOT attempt to stop the flywheel rotating by inserting a screwdriver between the flywheel and any other parts.

Remove the flywheel with a flywheel or harmonic balancer puller. Using a jaw-type puller may bend thinner flywheels. Follow the instructions supplied with the puller. DO NOT attempt to knock the flywheel off with hammer blows. This may result in damage to the crankshaft, flywheel, bearings or body parts.

Clean the points by drawing a white business card soaked with carb cleaner through closed points. Repeat until the card draws clean. It is rarely necessary to use abrasives. If you must, use the finest grit possible to achieve results. DO NOT use a points file as it generally removes far more material than necessary. A points file should be used only when the points are severely pitted or are not closing squarely.

It should not be necessary to reset the points. If required, consult your manual.

Replace flywheel, nut and recoil.

Starter

Manual start: Inspect the rope and handle for signs of damage or wear. Replace as necessary Follow the maintenance procedures in your manual to lubricate and adjust the recoil.

Electric start: clean and lubricate the bendix drive as per your manual.

Lubrication

Lube all moving parts including throttle linkage (white lithium) and steering shaft (chassis lube is OK). Some motors have a grease nipple on the swivel.

Carburetors

Procure an appropriate carburetor rebuild kit. Most parts houses have kits that cover a range of years and horsepowers, so don’t be surprised if you have extra parts. Remove and disassemble carburetor(s). If your carb kit has welch plugs (small round aluminum disks), and you have the skills to do so, remove the old plugs. Soak in carb. cleaner or spray with aerosol carb. cleaner, paying particular attention to all small passages and fuel-ways. Blow dry with compressed air, again, paying particular attention to internal passages. Install new welch plugs by using a small socket from your socket wrench kit to tap on. Plugs must be flat or slightly convex to seal properly If kit doesn't include a new needle and seat, get one.

If the float is cork, replace it with a plastic one. Some kits include them. If the float is plastic, make sure the integrity has not been compromised. Re-install and link and sync according to your manual.

Replace all under-cowl fuel lines where they are found to be brittle or cracking.

Fuel pump

Using your manual as reference, remove fuel pump and clean metal parts with carb. cleaner. Install a new fuel pump kit, or replace fuel pump entirely. Replace fuel filter and any vacuum hoses that may be connected.

Fuel tank

Test your squeeze bulb and fuel line. If either appear hardened or cracked, replace them. OEM replacements seem to have the longest life span.

Note: on dual-line tanks, there is no squeeze bulb, but the diaphragm and/or cork gasket may need replacing.

Drain fuel tank. With a flashlight, inspect for dirt, debris, or rust. If OK, rinse and refill with correct fuel/oil mix. Copious amounts of carb. cleaner or lacquer thinner will be required to clean out hardened fuel sediment.

If there are quick release connectors on the fuel lines, check the small o-rings at either end. Replace if necessary; bend a small diameter stiff wire or nail into an ‘L’ and use the short end of the L to pry the o-ring out.

Controls

If remote control, check throttle and gearshift cables for proper operation. If you have a remote helm, consider lubing the throttle/shifter as well (requires careful disassembly).

Carburetor Adjustment - Single S/S Adjustable Needle Valve

Initial setting is: Slow speed = seat gently, then open 1-1/2 turns.

Start engine and set the rpms to where it just stays running. In segments of 1/8 turns, start to turn the S/S needle valve in. Wait a few seconds for the engine to respond. As you turn the valve in, the rpms will increase. Lower the rpms again to where the engine will just stay running.

Eventually you'll hit the point where the engine wants to die out or it will spit back (sounds like a mild backfire). At that point, back out the valve 1/4 turn. Within that 1/4 turn, you'll find the smoothest slow speed setting.

Repeat for additional carbs.

Note: As a final double check setting of the slow speed valve(s), if the engine has more than one carburetor, do not attempt to gradually adjust all of the valves/carburetors at the same time. Do one at a time until you hit the above response (die out or spit back), then go on to the next valve/carburetor. It may be necessary to back out "all" of the slow speed adjustable needle valves 1/8 turn before doing this final adjustment due to the fact that one of the valves might be initially set ever so slightly lean.

When you have finished the above adjustment, you will have no reason to move them again unless the carburetor fouls/gums up from sitting, in which case you would be required to remove, clean, and rebuild the carburetor anyway.

Note: These adjustments are best performed on the boat, where air and water temperatures are similar to normal operation. If performed in a tank, make sure you are ducting or blowing exhaust away from the engine as fumes will circulate back into the air intake and skew your results.

Carburetor Adjustment - H/S Adjustable Needle

Most modern engines are equipped with fixed high speed jets, therefore the following procedure is unnecessary.

This requires 2 people: a driver and a mechanic. If the H/S adjustment has been changed significantly to the point where the engine will not start, commence with the adjustment set at ¾ turn out clockwise from lightly seated – most engines will start at that setting.

With the motor(s) running at full throttle, with the proper size screwdriver or the high speed knob, slowly start turning one of the H/S needles counterclockwise until the engine starts to bog down. Note the position, then turn it back clockwise until the motor misses or threatens to stall. Again, note the position.

At that point, back that needle valve out until the setting is at the mid point of the two settings noted above. You can experiment with fine adjustments and pick the one that (to your ears) has the highest rpm.

Now, go to the other High Speed needle (for multicarb engines) and repeat that procedure.

For multicarb engines, lift the center lever adjustment off the high ridge (depends on model), keeping it lifted until the point is facing the engine, then lower it into its proper position. (When you turn that lever now, you're adjusting both High Speed needle valves at the same time.)

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