Compression Test - Honda CB350 Repair Manual

Generally, a tune—up should consist of
the following operations:
a. A compression check;
b. Adjusting the cam chain;
c. Adjusting the valve clearance;
d. Cleaning and gapping (or replac—
ing) the contact breaker points;
e. Checking or adjusting the igni—
tion timing;
f. Cleaning and gapping (or replac—
ing) the spark plugs;
g. Checking the
level;
h. Setting carburetor idle speed and
idle mixture.
The type of equipment needed for the
above operation will differ for the various
models. You should have a thin points
file, a set of feeler gauges, a wire brush,
some emery cloth, and solvent, in addi—
tion to the normal hand tools.
For ignition timing, timing marks are
provided on the alernator rotor. How—
ever, a device is needed to determine ex—
actly when the points open (this is when
the plug fires). For this purpose, a test
light or a continuity light can be used. An
ohmmeter can be used as well.
Alternately, an automotive—type strobe
light can be used. The strobe light can be
used to check the timing both at an idle
and at full advance and therefore this
carburetor float
24
"dynamic' method is considered the
most accurate method of setting the igni—
tion timing.
NOTE: To be effective, a tune—up must
be performed on a mechanically sound
engine. Failure of a careful tune—up to
restore lost power or performance may
mean that engine components such as
rings are worn, or that the valves are
not properly seated.
Compression Test
1. A compression check should be
made before each tune—up since this will
give a general idea as to engine condi—
tion.
2. The engine should be at operating
temperature when checking compres—
sion.
3. Remove both spark plugs and insert
the gauge into one of the spark plug
holes. If the gauge is the "hold—in" type,
use a bit ofoil on the rubber tip to give a
good seal.
4. Hold the throttle and choke wide
open while kicking the engine over
briskly. Note the compression reading