Special Feature - Suzuki EN125-2A Service Manual

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SPECIAL FEATURE

TRANSISTORIZED IGNITION SYSTEM WITH ELECTRONIC ADVANCE
DESCRIPTION
On the Model EN125-2A, the timing advance characteristics of the ignition timing have been changed
from the previously-employed mechanical timing advance system incorporating a centrifugal advance
governor to an electronic timing advance system.
The introduction of this new electronic timing advance system minimizes fluctuations in the ignition
timing and also has improved the timing advance performance during high-speed operations.
The ignitor has the following functions:
(1)Revolution advance angle control
Controls ignition timing in response to engine r/min.(See Fig.1,)
(2)Closing angle control
When engine speed is low, reduces the conducting period (closing angle) of the transistor (Tr) so
that power consumption is reduced; when engine speed is high, increases the conducting period
(closing angle) to prevent voltage drop of the ignition coil. (See Figure 2 and 3.)
30
20
10
BTDC
0
O
13 BASE
0 1 2 3
Engine r/min (x 1000 r/min)
Signal generator
Signal rolor
O O
16.9 3 /7000rpm
O O
19.0 2.8 /4500rpm
4 5 6 7 8 9 10 11
Fig.1
Ignitor unit
(A)
(B)
Pick-up coil
O
200
O
100
1.0
0.5
Ig
1
( C)
(Tr)
2 4 6 8
Engine r/min (x 1000 r/min)
Fig.2
2 4 6 8
Engine r/min (x 1000 r/min)
Fig.3
Ignition switch
Ig
2
Battery
Ignition coil
Spark plug
10
10