SECTION 7

IGNITION SYSTEM

DESCRIPTION

This section gives complete service procedures for both flywheel and distributor type magnetos. In addition, instructions are included for afprøvning coils, condensers, and breaker point assemblies, for rensning and re-gapping spark plugs, for checking, adjusting and reparationing vacuum cut-out and safety switches, and for checking and remagnetizing flywheel magnets. Operation of a typical magneto is discussed in Section 2, Principles of Operation. Spark plugs and their relation to motor performance are discussed in Section 3, Performance Analysis. The following chart shows the komponenter used on the ignition system of 5 hk LD110:

The complete ignition system used on all two-cylinder motors consists of a flywheel type magneto connected to the spark plugs through high tension leads (see Figure 7-1). The pushbutton stop switch or ignition key switch, and vacuum cutout switch, are also part of the ignition system on some models. The magneto is a self-contained unit consisting of an armature plate with two ignition coil and lamination assemblies, condensers, and breaker point assemblies. A permanent magnet cast into the flywheel completes the assembly. Breaker point assemblies are made to open and close at exactly the right moment by a cam on the crankshaft. The degree of spark advance is made to vary with throttle opening by means of linkage between the armature plate and throttle control.

FLYWHEEL TYPE MAGNETOS

1. Remove Ready-Pull starter, if used.
2. Remove spark plug leads by twisting counterclockwise (see Figure 7-4). Remove ignition lead anchor from cylinder head.
3. Disconnect leads from stop switch and vacuum cutout switch, if used. To disconnect Packard connectors, lift up on locking tabs and slide connectors apart (see Figure 7-5).
4. Remove flywheel nut, using a flywheel holding tool (see Figure 7-6). Pull flywheel from crankshaft (see Figure 7-7), using flywheel puller (see Section 15, Special Tools).
5. Disconnect magneto throttle linkage.
6. Loosen four Phillips head screws attaching magneto armature plate to power head (see Figure 7 -8). Lift magneto assembly from power head.

For conclusive afprøvning, the coils and condensers should be removed from the armature plate. The breaker points, however, are tested on the armature plate and are removed only for udskiftning.

1. Remove all lead clamps from bottom of armature plate.
2. Pull the high tension leads from the coil assemblies. Disconnect coil primary leads and condenser leads, and shorting lead assemblies and vacuum cutout switch leads, if used, from breaker assemblies.
3. Remove coils and condensers from armature plate. Test ignition komponenter as described under "Test Procedures for Coils, Condensers, and Breaker Points." Check spark plugs as described under "Spark Plug rensning and inspektion."

1. Install breaker assemblies over the armature plate pins.
2. Install the condensers.
3. Insert shorting lead assembly and vacuum cutout switch leads through grommets in armature base. Insert high tension leads into magneto coils.
4. Install coil assemblies with a new oiler clip and wick in position on the upper cylinder coil mounting boss (see Figure 7-9). The upper cylinder coil is nearest the timing marks on the rim of the armature plate. DO NOT tighten coil mounting screws at this time.
5. Note machined bosses on armature plate (see Figure 7-10). Adjust coil position so that coil heel rests flush with face of machine boss. Tighten coil mounting screws to torque specified in Section 5.
6. Reconnect all leads on the magneto, making sure that connections are clean and tight. Replace lead clamps on bottom of armature plate.

1. If flywheel key has been removed, reassemble with outer edge parallel to center line of crankshaft (see Figure 7-11).

   CAUTION!

   Be sure that the single upset mark on side of key is facing down. Incorrect installation of key will affect cam position and result in late (retarded) ignition timing.
2. Install cam, making certain that side marked "TOP" is up.
3. Apply a light coating of OMC Type A lubricant to the magneto support and to the retaining ring. Align holes of magneto support ring to correspond to position of magneto (see Figure 7-12). Do not add oil or grease to the oiler wick on the magneto.
   
   
4. Place magneto in position over crankshaft, being careful not to damage breaker arms on cam. Tighten four Phillips head screws.
   
   
5. Replace throttle linkage. Install armature detent and spring (9-1/2 HP only).
   
   
6. Check breaker point settings as described under "Breaker Point Adjustment."
7. Check crankshaft and flywheel tapers for any traces of oil. This assembly must be perfectly dry; swab tapered surfaces with solvent and blow dry with compressed air. Oil or grease remaining on tapers will permit the flywheel hub to spread. Inspect both tapers for burrs or nicks.

CAUTION!

DO NOT permit solvent used to clean tapers to wash oil out of oiler wick.
8. Replace flywheel. Check for spark on each cylinder by connecting the spark plug high tension leads to a spark checker and cranking the engine with a starter rope (see Figure 7-13). Tighten flywheel nut to torque specified in Section 5.
9. Connect the high tension lead wires to the spark plugs. Make sure that the spring clips in the spark plug lead covers make firm contact with the spark plug terminals (see Figure 7-14). Connect stop switch and vacuum cutout switch leads, if used.
10. Replace Ready-Pull starter and fuel tank, if used.

TIMING AND BREAKER POINT ADJUSTMENT

1. For breaker point adjustment, magneto must be assembled to motor and flywheel must be removed.
2. Connect continuity meter between a suitable armature plate ground and forward breaker point insulated terminal screw.
3. Place timing fixture (see Section 15, Special Tools) on crankshaft (see Figure 7-15). Rotate crankshaft so that mark on the end of fixture marked "T" (top) is aligned midway between the two projections on the armature plate.
   Rotate the crankshaft in a clockwise direction ONLY to avoid water pump impeller damage.
4. Move the timing fixture slowly in a clockwise direction until the exact instant at which the points open or close are determined, as indicated on the continuity meter. The points should break open when the timing mark is midway between the two projections on the armature plate.
5. If timing is not correct, align the timing fixture between the timing marks. Without loosening the breaker point lock screw, adjust points until the continuity meter just indicates an open circuit (see Figure 7-16). Turn the screw only until the meter indicates points open or no continuity: Do NOT adjust further.
6. Recheck timing as described in (d) above.
7. Use a feeler gage to adjust the breaker points only if a continuity meter is not available. (See Figure 7-17). Point gap
   should be set to .020 inch (.022 inch for new points) with the breaker arm on the highest point of the cam lobe (full open). For maximum performance recheck the point setting with a continuity meter at the first opportunity.
8. Rotate crankshaft through 1800 clockwise and repeat entire procedure for second set of points.
9. Reattach leads to breaker assemblies and replace flywheel. Check for spark on each cylinder by connecting the spark plug high tension leads to a spark checker. Tighten flywheel nut to torque specified in Section 5. Connect lead wires to spark plugs, making sure that firm contact is made at the spark plug terminals (see Figure 7-14).

TEST PROCEDURES FOR COILS, CONDENSERS AND BREAKER POINTS

Breaker points should be inspected at least once each season and replaced whenever necessary. Under normal running conditions, breaker point contacts will appear slightly rough and gray in color. Abnormal points will appear excessively pitted, may have a considerable amount of material transferred from one contact surface to the other, and will generally be blue in color. This blue coloring indicates burning.

The occurrence of severe pitting or burning can usually be traced to such conditions as:

1. (1) high primary current,
2. (2) a faulty condenser, or
3. (3) deposits of foreign material, especially grease or oil, on the contact surfaces.

High primary current will occur on battery ignition systems if the wiring harness which runs from the engine to the dashboard has been altered, eliminating part of the ignition system wire. See "Ignition Resistor Wire." Faulty condensers require udskiftning. Foreign deposits can be attributed to careless handling of points during installation or the use of excessive lubricant on the breaker cam.

Both breaker point sets are identical. Point spring tension is predetermined and does not require adjustment once breaker assemblies are installed. In most cases, breaker contact alignment will not be necessary; however, should an occasion arise that requires a slight contact alignment correction, bend only the insulated part of the breaker set.

Clean the breaker plate thoroughly before installing new breaker points to provide a good ground between the breaker base and plate. Turn the eccentric screw in the plate until it bottoms so there is adequate screw engagement to hold breaker adjustment.

If new breaker points appear to have high resistance across their contact surfaces, making use of a continuity meter during breaker adjustment difficult, snap the contacts open and closed manually several times. DO NOT use an abrasive stone or file to remove resistance across new breaker contacts.

Dirt, foreign particles, and oil are detrimental to contact performance. The oils and acids from a person's hand, even though clean, can affect contact resistance. OIL deposits on the points will cause them to burn after a very abort period of operation. If points need rensning, use alcohol or trichloroethylene. Never file points - replace them.

To remove any traces of dirt from contacts, insert a piece of bias tape and work it up and down between the points.

The following four factors affect condenser performance; each factor MUST be considered in making any condenser test.

• Breakdown - a failure of the insulating material - a direct abort between metallic elements of the condenser. This prevents any condenser action.
• Low insulation resistance (leakage) prevents condenser from holding a charge. All condensers are subject to leakage which up to a certain limit is not objectionable.
• High series resistance - excessive resistance in the condenser circuit due to broken strands in condenser lead or to defective connections. This will cause burned points and ignition failure upon initial start and at high speeds.
• Capacity - determined by the design and the condition of the condenser.

A good magneto coil will not function properly if incorrectly mounted on the breaker plate or if incorrectly connected. If the coil heels are not properly aligned with the bosses on the breaker plate, the gap between the flywheel magnet and the coil heels may be too great, or the coil heels may drag on the flywheel. Connections that are not clean and tight will cause high resistance which will limit current flow. Visually inspect the coil mounting and connections before condemning a coil.

Check for leakage from the coil (caused by moisture, cracks in the coil housing, or carbon path), by using an ignition analyzer.

At relatively Blow engine speeds, the breaker points remain closed for long periods of time. The longer current is allowed to flow through the points, the batter the breaker point contacts become.

A one ohm register wire is used in the ignition coil primary circuit to limit current through the contacts at idling speeds. Thus operating temperatures of the contacts is reduced, and breaker point life is prolonged. Since the resistance of this wire (white with single red stripe, located in wiring harness between dashboard and engine) is determined by its length, DO NOT shorten or splice this wire. Replace the entire lead if reparations are necessary.

To determine accurately the condition of komponenter of the ignition system, an ignition analyzer should be used. Without the use of test equipment, coils, condensers, or breaker point assemblies may be replaced needlessly.

A wide variety of ignition analyzers is available from various manufacturers. In addition, same automotive testers having the proper specifications can be used. The use of the Graham, Merc-O-Tronic or Stevens ignition analyzers is particularly recommended, since these units have provisions for checking all functions of the ignitions system (see Figure 7-52).

Detailed instructions for the use of any tester are provided with the unit; therefore, only general information is given here. All komponenter of the ignition system should be checked, even though replacing a part seems to have corrected the trouble. For example, replacing points may have increased the spark, but further improvement will be realized if a condenser is found to be weak and is replaced.

Magneto and ignition coils should be tested for correct secondary resistance, correct primary resistance, coil polarity, and coil output. In addition, the coil insulation should be tested for leakage. Follow the equipment manufacturer's instructions.

The condenser should be tested for correct capacity, series resistance, and leakage resistance. The condenser should be replaced if it fails to meet any of the three tests.

Spark plug high tension leads, distributor caps, and rotors may be tested for leakage or insulation failures by using the ignition analyzer and an ignition coil (see Figure 7-53). Connect the coil to the ignition analyzer as for the coil test. Connect a separate test lead with suitable clips to the secondary terminal of the coil and to the conductor of the component being tested (lead terminals on distributor cap, rotor arm, or spark plug high tension lead). Probe the entire insulated surface of the component being tested with the grounded test probe. Arching will be apparent wherever the insulation has broken down, due to moisture or carbon trails. NOTE: Prior to installing high tension leads into distributor cap terminals, coat the threaded end with a good brand of dielectric lubricant. This will facilitate removal of these leads, especially in salt water areas.

SPARK PLUG rensning AND inspektion

The condition of spark plugs may provide an indication of other conditions requiring attention. Inspect each plug and gasket as it is removed. Place the spark plugs in a holder in order of removal to assist in locating trouble. Inspect each plug for worn electrodes, glazed, broken, or blistered porcelain, and replace plugs where necessary. Plugs that are severely carbon fouled, that have blistered or cracked insulator tips or plugs that have eroded electrodes must always be replaced. Plugs that are slightly contaminated with deposits, or which have wider than recommended gap settings can be cleaned and regapped for further use. Plugs that appear slightly contaminated can be cleaned by careful scraping using a very small knife or similar instrument. After combustion deposits have been removed, bend the side electrode back slightly so that the center electrode can be filed flat.

DO NOT clean plugs on abrasive blasting machines. This type of rensning tends to remove the hard, smooth porcelain glaze from the insulator tip and reduces the tip's resistance to the formation of combustion deposits. Blasting also tends to pack sand between the insulator tip and the metal case of the plug. If the sand is not removed before installing the plug, it may pass through the engine causing piston or cylinder wall scoring.

After the plug has been cleaned, adjust the gap as recommended by bending the side electrode. Use a round wire feeler gage (see Figure 7-54) to measure gap adjustment. Adjust only the side electrode, as attempting to bend the center electrode will crack the insulator.

Poor motor performance and premature spark plug failure may result from improper spark plug installation. Before installing the plug, be sure the plug seat in the cylinder head is cleaned and free from obstruction. Inspect spark plug hole threads and clean before installing plugs. Always use new gaskets when installing spark plugs. Tighten spark plugs to 20 to 20-1/2 foot pounds, using a torque wrench.

• Installation of plugs with insufficient torque to fully seat the gasket.
• Installation of the plugs using excessive torque which changes gap settings.
• Installation of plugs on dirty gasket seal.
• Installation of plugs to corroded spark plug hole threads.

VACUUM CUTOUT AND SAFETY SWITCHES

If the throttle is closed while the motor is operating in neutral, crankcase suction may become abnormally high. This high suction (vacuum) will cause erratic functioning of the carburetor, allowing the motor speed to increase. The function of the cutout switch is to short out the breaker point from the lower cylinder momentarily when crankcase suction increases, preventing the lower cylinder spark plug from firing and thus reducing motor speed. The safety switch opens the cutout switch circuit and prevents it from operating at full throttle.

If the vacuum cutout switch is not functioning, check the manifold vacuum hose for leaks, and check the hole in the intake manifold (see Figure 7-55) with a No. 76 drill to make sure that it is not clogged. To check the operation of the cutout switch, connect a continuity meter to the switch terminal and to ground. Alternate suction and pressure applied at the switch vacuum hose connector will indicate switch operation.

If switch operation is faulty or erratic, disassemble the cutout switch and inspect the diaphragm and contacts. Replace parts as required and reassemble (see Figure 7-56).

Safety switches are provided on models using electric starting to prevent engaging starter at full throttle and on models using vacuum cutout switches prevent the cutout switch from operating at full throttle. Use a continuity meter connected between switch terminal and ground to check safety switch.

Adjust the safety switch position as follows:

Two cylinder engines (see Figure 7-57) - advance armature plate slowly from idle position until end of shifter lock stop is 1/4 inch from boss on cylinder. At this point switch contacts should open and break continuity. NOTE: If contacts break early, move switch toward shifter lock cam. If contacts break late, move switch away from shifter lock cam.

FLVWHEEL MAGNET CHECKING AND RE-MAGNETIZING

Flywheel and rotor magnets are designed to hold their magnetism indefinitely. However, charging or boosting is occasionally required. This is accomplished with the use of a charging unit. Complete instructions for charging magnets are included with the charging unit.

All magnets have two poles - north and south. Magnetic lines of force flow around the poles from north to south. When charging, the north pole of the magnet to be charged should contact the south pole of the magnet charger; the south pole of the magnet should contact the north pole of the charger. When properly charged, leading pole of the magnet should be south.

Determine polarity of the magnet to be charged with a compass, if it is not already known. North seeking pole of the compass will point to the south pole of the magnet. Adjust pole shoes to approximate radius of the magnet to be charged, and press charging switch to recharge magnet.