General Information
1-26
Compression Gauge
A compression gauge (Figure 33)
measures combustion chamber
(cylinder) pressure, usually in PSI or kg/
cm
2
. The gauge adapter is either
inserted or screwed into the spark plug
hole to obtain the reading. Disable the
engine so it does not start and hold the
throttle in the wide-open position when
performing a compression test. An
engine that does not have adequate
compression cannot be properly tuned.
Refer to Chapter Three.
Multimeter
A multimeter (Figure 34) is an essential
tool for electrical system diagnosis. The
voltage function indicates the voltage
applied or available to various electrical
components. The ohmmeter function
tests circuits for continuity, or lack of
continuity, and measures the resistance
of a circuit. Some manufacturer’s
specifications for electrical components
are based on results using a specific
test meter. Results may vary if using a
meter not recommended by the
manufacturer. Such requirements are
noted when applicable.
Ohmmeter (analog) calibration
Each time an analog ohmmeter is used
or the scale is changed, the ohmmeter
must be calibrated. Digital ohmmeters
do not require calibration.
1. Make sure the meter battery is in
good condition.
2. Make sure the meter probes are in
good condition.
3. Touch the two probes together and
observe the needle location on the
ohms scale. The needle must align
with the 0 mark to obtain accurate
measurements.
4. If necessary, rotate the meter ohms
adjust knob until the needle and 0
mark align.
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