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User Manual
Ignition
The Raket 120 engine is equipped with a solid state ignition system, which
consists of a minimum of parts.
·
The ignition coil with built in electronics.
·
The flywheel with the permanent magnet.
·
The emergency breaker = stop button.
When the flywheel rotates past the ignition coil, an electric current is gene
-
rated. At a certain position of the flywheel in relation to the ignition coil, the
electronic circuit, which is integrated in the coil assembly, causes the coil to
produce a high tension spark for the spark plug.
As there are no moving parts, there is no setting needed. The only measure
that can influence the ignition is the distance between flywheel and the yoke
of the ignition coil. If you have disassembled the engine, first mount the
flywheel on the shaft. Don’t forget the crankshaft key. Tighten the flywheel
nut with 5 kg. Then place a stainless (non magnetic) feeler gauge 0,35 mm
thick between the yoke of the coil and the part of the flywheel where the
pole shoes of the magnet are seen. Tighten the screws that hold the coil to
the crankcase.
The only maintenance for the flywheel itself is cleaning. Also make sure that
the starter claws near the centre can move freely.
Never attempt to make any modifications of the flywheel. If the flywheel is
damaged, replace it with a new one. See also under Safety precautions.
The emergency breaker
On the coil there is an electric contact which must be connected to the
emergency breaker. When this contact is short circuited to ground ( i.e. to
the metal parts of the engine) the ignition is stopped. Depending on appli-
cation the emergency breaker can have many different designs. It is your
responsibility to make sure that the breaker is placed so that it can be easily
reached from the place of normal operation. On a kart it is convenient to
place the stop button on the steering wheel.
Spark plug
The spark plug is a special design for this type of engine. When you replace
the spark plug, make sure that you get an original part or an identical repla-
cement. Other spark plugs can permanently and mechanically damage your
Raket engine.
In original the Raket 120 engine is equipped with a Nippondenso W22MP-U
spark plug. This has the correct length of the threaded part which exactly
matches the threaded part of the cylinder.
The correct distance between the centre electrode and the side electrode
is 0,4 mm. This distance shall be measured with a piece of wire, 0,35 mm
in diameter.
During normal operation the spark plug shall have a brownish surface on
the centre electrode. However, the colour can differ a lot. If you stop the
engine directly after heavy load, the centre electrode can be light grey or
light brown. On the other hand, if your engine has been idling for a while be-
0,35 mm
0,5 - 0,7 mm
DO NOT SCALE DRAWING
Denso_Spark_Plug
SHEET 1 OF 1
UNLESS OTHERWISE SPECIFIED:
SCALE: 2:1 WEIGHT:
REV
DWG. NO.
A
SIZE
TITLE:
NAME
DATE
COMMENTS:
Q.A.
MFG APPR.
ENG APPR.
CHECKED
DRAWN
FINISH
MATERIAL
INTERPRET GEOMETRIC
TOLERANCING PER:
DIMENSIONS ARE IN INCHES
TOLERANCES:
FRACTIONAL
ANGULAR: MACH BEND
TWO PLACE DECIMAL
THREE PLACE DECIMAL
APPLICATION
USED ON
NEXT ASSY
PROPRIETARY AND CONFIDENTIAL
THE INFORMATION CONTAINED IN THIS
DRAWING IS THE SOLE PROPERTY OF
<INSERT COMPANY NAME HERE>. ANY
REPRODUCTION IN PART OR AS A WHOLE
WITHOUT THE WRITTEN PERMISSION OF
<INSERT COMPANY NAME HERE> IS
PROHIBITED.
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