buell s1 lightning '97 Manual

 

The vacuum-operated electric switch (V.O.E.S.) is attached to
the carburetor. The V.O.E.S. senses intake passage vacuum
through a carburetor hose connection. The switch is open
during acceleration and high engine load conditions (low vac-
uum) and is closed during deceleration and low engine load
conditions (high vacuum). The ignition module is programmed
with two spark advance curves to meet varying engine loads.

The high-vacuum curve, selected for maximum spark
advance under normal light-load cruising conditions, provides
improved fuel economy and performance. The low-vacuum
curve (retarded spark) minimizes spark knock while maintain-
ing performance under high-load conditions (acceleration and
highway driving).

The ignition module selects the proper curve when it receives
an open or closed electrical signal from the V.O.E.S. This sys-
tem ensures correct timing to suit starting and high-speed
requirements.

A single ignition coil fires both spark plugs simultaneously.
The spark plug in the front cylinder fires at the end of that cyl-
inder’s compression stroke, thereby igniting the air/fuel mix-
ture. At the same instant, the spark in the rear cylinder fires
ineffectually during the end of that cylinder’s exhaust stroke.
During the next engine revolution, the simultaneous firing of
the spark plugs will occur during the middle of the front cylin-
der’s exhaust stroke and at the end of the rear cylinder’s com-
pression stroke (thereby igniting the air/fuel mixture in the
rear cylinder).

 

The rotor and sensor plate are located in the gearcase cover
on the right side of the motorcycle. The rotor is mounted on
the camshaft and operates at one-half crankshaft speed. As
the rotor turns, slots in its outside diameter break the mag-
netic field of a Hall-effect device mounted on the sensor plate.
The output of the Hall-effect device is a logic-type signal that
corresponds to the timing information from the spinning rotor.
This technique gives accurate timing information down to “0”
speed.

The ignition system produces a spark near top dead center
(TDC) for starting. At RPM’s and loads above this, the system
produces a spark 5˚-40˚ before TDC. The whole timing pro-
gram can be shifted by mechanical rotation of the sensor
plate. See IGNITION TIMING in Section 1.

The ignition module contains all the solid-state components
used in the ignition system. The dwell time for the ignition coil
is also calculated by the microprocessor and is dependent
upon engine speed. The programmed dwell is an added fea-
ture to keep battery drain to a minimum and to adequately
charge the coil at all speeds. The ignition module has added
protection against transient voltages, continuous reverse volt-
age protection and damage due to jump starts. The system
will operate down to 5.7 VDC. The ignition module is fully
enclosed to protect it from vibration, dust, water and oil. The
unit is not repairable–it must be replaced if it fails.

See the wiring diagrams at the end of this section for addi-
tional information on ignition system circuits.

 

Perform the following tests if the engine will not start, or if
hard starting or missing indicates a faulty operating ignition
system.

 

1.

Disconnect spark plug cables from spark plugs. Check
condition of plugs and cables. Clean or replace as nec-
essary.

2.

Insert a conductive adapter into spark plug cable end
and establish a 3/16 in. (4.8 mm) gap between adapter
and cylinder head. Turn on ignition and “engine stop”
switches. With transmission in neutral, press “engine
start” button. Check for a spark across plug electrode
gap. If a spark is produced, problem is not in electronic
system or coil – check carburetion, enrichener and spark
plugs. If no spark is produced, check battery voltage and
battery connection condition. Battery voltage must be 11-
13 VDC. Charge battery if voltage is low.

3.

Verify that the ground strap from swingarm mount block
to below the circuit breakers is in good condition. If there
is still no spark, then perform the tests under NO IGNI-
TION SPARK below.

 

See 

 To conduct the following tests, it will be nec-

essary to assemble a set of jumper wires. Cut two wires of
ample length to reach from a good ground connection to the
negative terminal of the coil primary. If a suitable capacitor is
not available, use a condenser (such as the type used in ear-
lier breaker point ignition systems). When conducting Steps 3
and 5 of the following spark tests, connect a spare spark plug
to one of the plug wires and lay the spark plug on the engine
cylinder head. During the testing procedures, check for spark
across the spark plug electrodes.

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