Rotax MMH-912 Series, Руководство по обслуживанию

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74-00-00
page 6
October 01/2010
Effectivity 912/914 Series
Edition 1 / Rev. 3
d04778
BRP-Powertrain
Maintenance Manual
2.1.1) Ignition
See Fig. 74-4.
As already stated, the engine is equipped with dual ignition of a
breakerless capacitor discharge design (DCDI). That means that the
ignition unit comprises two independently working ignition circuits
(separate trigger coil, electronic module, charging coils etc.).
◆
NOTE: The ignition unit cannot be disassembled and needs no
adjustment.
Each ignition circuit consists of two ignition branches. Ignition occurs on
cylinder 1 and 2 simultaneously every 360° as well as on cylinder 3 and
4 but 180° offset.
◆
NOTE: Due to engine design, ignition occurs also at "the TDC
of the exhaust stroke", but this has no effect on engine
operation.
The engine is furnished with an automatic ignition timing controlled by
the edge of trigger cams on the fly wheel hub and the electronic
modules.
◆
NOTE: For easy engine start, the ignition timing at start is 4°
B.T.D.C. for ignition circuit A and B.
As soon as the engine runs, the ignition point will change over
automatically to operation ignition.
On the 912 Series:
On the 914 Series: ignition circuit A 26°
ignition circuit B 22°
The transition from start ignition timing to the timing for operation takes
place between 650 and 1000 rpm.
Differences between electronic module
part no. 966726 and part no. 966727:
switching to advanced ignition:
ignition timing in normal operation:
from 650 to 1000 RPM
depending on trigger gap
after the expiration of
the time delay (3-8 sec.)
26° before T.D.C.
26° before T.D.C.
none
3 - 8 sec.
4° Before T.D.C.
3° After T.D.C.
4° Before T.D.C.
3° After T.D.C.
time delay for ignition at start:
ignition point at start 966871 current
966872 new
fly wheel hub
current 966726
new 966727