AD Boivin 2002 Snow Hawk, Service Manual

Page: 168 / 173

1
700, rue Jean-Marchand
Lévis , QC Canada G6V 9G6
Tél.: (418) 838-3783 Fax.: (418) 838-3957
Web site:
www.adboivin.com
2002 Snow Hawk Hi-Altitude Carburetor and Clutching Set-up:
GENERAL
Since the 2002 Snow Hawk uses individual carburetor filters, carburetor inlet temperature is not
always the same as outside temperature, thus jetting is not. Influences from engine heat and
the exhaust system have a tendency to increase the engine bay temperature relative to outside
air temperature. We have plotted their approximate relationship in the graph shown on the
fourth page of this guide.
PROCEDURE - JETTING
How to use the Jetting chart:
1.
Measure the outside (ambient) air temperature
2.
Determine the altitude at your location
3.
Using the chart on page four of this guide, determine the range of temperatures at the
carb inlet by first drawing a horizontal line to the right, away from the vertical ambient air
temperature axis.
4.
Second, draw a vertical line upwards from each of the intersection points where the
horizontal line crosses over the Best Line , the MIN T
o
line and the MAX T
o
line .
5.
The temperature values where each of these vertical lines intersect the horizontal carb
inlet temperature axis are the approximate min, median and max temperatures that are
normally found at the carb inlet during normal operation at the specified outside air
temperature.
6.
Adjust jetting set-up according to the carb inlet temperature given by the intersection of
the Best Line and the ambient air temperature line.
7.
After a short trial run, observe the plug color and performance feel of the vehicle closely.
If the mixture is too rich, try jetting according to the MAX T
o
line ; If the mixture is too
lean, try jetting according to the MIN T
o
line .
8.
The correct set-up will normally lie in this range.
9.
An example is shown on page three of this guide where the outside air temperature
(ambient) is shown as –15
o
C . The resulting approximated carb inlet temperature ranges
from 31
o
C (minimum carb inlet temperature) to 36
o
C (maximum carb inlet temperature)
with the best approximation of the carb inlet temperature at 33
o
C .
NOTE: This set-up is a recommendation only. It is the responsibility of the owner to pay close
attention to spark plug color and engine performance when modifying the stock set-up to avoid
lean burn-down.