BRP ski-doo MACH Z 1000 SDI, Handbook

Page: 147 / 493

SECTION 05 - ENGINE PREPARATION
MMC2005-001_05A.FM
05-23
Needle jets are stamped with an alphanumeric
code. The letter indicates a major change in fuel
flow. P-2, for example, indicates low flow; P-4,
greater flow, and so on. The number indicates mi-
nor adjustments in fuel flow. The first diagram
shows the relationship between the alphanumeric
needle jet size number and fuel flow.
NOTE: Needle jets carrying the numbers 166, 159
or 169 in addition to the P-2 or P-4 and are not
interchangeable. Be sure correct needles are used
as specified for your snowmobile.
Main Jet System
PRINCIPLES OF OPERATION
1. Jet needle
2. Metered here
3. Fuel
4. Air
5. Needle jet
The main jet system starts to function when the
throttle is approximately 1/4 open. The mid range
fuel is supplied by the main jet and regulated by
the needle jet/jet needle combination. The main
jet meters the fuel when the throttle is in the wide
open position.
The main jets are available in sizes from number
50 to number 840. The size number corresponds
to flow and not necessarily to hole size.
When experiencing erratic operation or overheat-
ing, check the main jet for dirt which can plug the
orifice.
A01C4JA
Throttle valve opening (%)
Fuel flow
15 25 50 100
1
2
3
A01C4KA
Increasing needle jet size
Fuel flow increasing
O-8 O-8
P-2 P-4 P-6 P-8
Q-0 O-8 O-8
P-2 P-4 P-6 P-8
Q-0
2
1
5
A01C30A
1
2
3
4