SECTION 05 - ENGINE PREPARATION
MMC2005-001_05A.FM
05-27
Mikuni TMX Carburetor (tuning parts)
Part numbers with a 486 prefix must be ordered
from Valcourt Race Dept. All others must be or-
dered from your local Ski-Doo dealer.
IGNITION SYSTEMS, SPARK
PLUGS
Two-stroke engines in snowmobiles rely on an
electric spark to initiate combustion of the fuel/air
charge which has been inducted into the cylinder.
For the engine to operate efficiently, the spark
must be delivered at precisely the right moment
in relation to the position of the piston in the cylin-
der and the rotational speed of the crankshaft.
Additionally, the spark must be of sufficient inten-
sity to fire the fuel mixture, even at high compres-
sion pressure and high RPM.
It is the function of the ignition system to generate
this voltage and provide it to the spark plug at the
correct time.
The Nippondenso capacitor discharge ignition
(CDI) system has magnets located on the crank-
shaft flywheel. AC voltage is induced in the gen-
erating coil(s) as the poles of the magnets rotate
past the poles of the coils. Timing is controlled by
a trigger coil or the position of the coil poles rela-
tive to the magnet poles, which are directly related
to piston position. The CD (or amplifier) box con-
tains the electronic circuitry to store and control
the initial voltage and deliver it to the ignition coil
(and then the spark plug) at the correct moment.
The ignition coil is a transformer that steps up the
relatively low voltage, 150-300 V, of the generat-
ing coil to the 20,400 – 40,000 volts necessary to
jump the spark plug gap and initiate the burning of
the fuel/air mixture in the combustion chamber.
Maximum power from a given engine configura-
tion is produced when peak combustion chamber
pressure (about 750 PSI) takes place at about 15°
of crankshaft rotation ATDC. Normal combustion
is the controlled burning of the air/fuel mixture in
the cylinder. The flame is initiated at the spark plug
and spreads to the unburned mixture at the edges
of the cylinder.
This flame front travels through the cylinder at
about 100 feet per second. In order to achieve
maximum pressure at about 15° ATDC, the spark
must occur about 15° before TDC. Complete com-
bustion will finish at about 35° ATDC. The actual
amount of spark advance BTDC is dependent
upon bore size, combustion chamber shape, oper-
ating RPM, mixture turbulence and the actual flame
speed.
P/N
DESCRIPTION
486 212 400
Pilot Jet, 15
486 212 500
Pilot Jet, 17.5
486 212 600
Pilot Jet, 20
486 212 700
Pilot Jet, 22.5
404 161 870
Pilot Jet, 25
486 212 800
Pilot Jet, 27.5
404 162 042
Pilot Jet, 30
707 200 100
Pilot Jet, 32.5
707 200 168
Pilot Jet, 35
707 200 136
Pilot Jet, 40
486 230 100
Pilot Jet, 45
486 230 200
Pilot Jet, 50
486 230 300
Pilot Jet, 55
486 230 400
Pilot Jet, 60
486 230 500
Pilot Jet, 65
486 213 200
Piston Valve, 3.0
486 213 300
Piston Valve, 3.5
404 161 867
Piston Valve, 4.0
486 213 400
Piston Valve, 4.5
486 213 500
Piston Valve, 5.0
404 161 868
Inlet Needle & Seat 1.5
404 161 871
Needle, J8-6FIY05-58
404 161 872
Needle, J8-6FIY04-59
404 161 873
Needle, J8-6FIY06-57
Содержание ski-doo MACH Z 1000 SDI
Страница 1: ...Mmc 2005 001 Racing FH8 Wed Sep 15 15 27 01 2004 Page 1 C M Y CM MY CY CMY K...
Страница 118: ...04 36 MMC2005 001_04A FM SECTION 04 SUSPENSION SC 3 SC 4 RAS SC IV REAR SUSPENSION 0...
Страница 124: ...04 42 MMC2005 001_04A FM SECTION 04 SUSPENSION SC 3 SC 4 RAS...
Страница 196: ...05 72 MMC2005 001_05A FM SECTION 05 ENGINE PREPARATION FUEL TANK AND FUEL PUMP All Models except SDI 2 4 3 1 A33C2VS...
Страница 289: ...SECTION 06 DRIVE SYSTEM MMC2005 001_06A FM 06 27 422 A01D3JA 417 222 562 427 A01D3KA 417 222 677...
Страница 473: ...SECTION 12 SERVICE TOOLS MMC2005 001_12A FM 12 29 N Scratch remover P N 861 774 800 APPLICATION All models...
Страница 476: ...MMC2005 001_13A FM 13 1 SECTION 13 ACCESSORIES TABLE OF CONTENTS 0 ACCESSORIES 13 02...
Страница 493: ...Mmc 2005 001 Racing FH8 Wed Sep 15 15 27 01 2004 Page 1 C M Y CM MY CY CMY K...