Break-In Operation; Basic Theory - Robin America EH12-2, EH17-2, EH25-2 Service Manual

5-5 BREAK-IN OPERATION
B
An engine that has been completely overhauled by being fitted with a new piston, rings, valves and
connecting rod should be throughly RUN- IN before being put back into service.
Good bearing surfaces and running clearances between the various parts can only be established by
operating the engine under reduced speed and loads for a short period of time.
While the engine is being tested, check for oil leaks.
Make final carburetor adjustment and regulate the engine operating speed.
Steps
10 min
3600 rpm
No load Step
3
10 min 3000 rpm No
load
Step
2
10 min 2500 rpm No load
Step
1
Time
Engine speed Load
1
Step
4
EH12-2
EH17-2
EH25-2
1
1.5
KW b.OHPI
1
3600 rpm
1.OKW 1.4HP
2.4KW 3.2HP
30 min
Step
5
EH12-2
EH25-2
EH17-2
1
$:A
f::
1
3600 rpm 60 min
4.7KW 6.4HP
6. IGNITION SYSTEM
6-1 TYPE
OF
IGNITION SYSTEM
EH12-2 employs the U. T. C. I. (Universal type Transistor Controlled Ignition) pointless ignition system.
EH17-2 and EH25-2 have the T. I. C. (Transistor, Igniter, Circuit) pointless ignition system.
AS optional parts, these ignition system may be implemented with lamp.coi1, charge coil and excitor coil.
6-2 BASIC THEORY
To ensure the easy startability of the engine, the step advancing ignition timing system is incorporated in
the ignition coil. This system enables the engine
to
have basically two different ignition timings
according to the engine speed. Following are the explanation how the system works.
1) At lower speed of the engine
Rotation of the flywheel induces current I,, as this current flows through the base terminal of the
power transister, it is activated and the current IZ starts flowing.
As the engine reaches the ignition timing, the ignition timing control circuit for the lower engine speed
is activated and lets the current
L
flow through the base terminal of the power transistor.
This generates the collector current L which will bypass the current 11 and abruptly shut off the current
IZ
because the power transistor is turned off.
This sudden current change generates a big voltage on the secondary side of the ignition coil and
which sparks the spark plug.
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