BOMBARDIER 1996 Ski-doo MX Z440 Handbook page 316

Ice : Stud quantity is directly related to horsepower on the ice. Up to about 80 HP, 4to 5 ice picks
per pitch should be used for a total of 200-250 studs. 80 to 105 HP should need 6 to 7 picks per
pitch for a total of 300-350 studs. Over 110 HP will require 7 to 8 picks per pitch and possibly
hooker plates welded to the track guides.
o
NOTE : The installation of hooker plates will require modification to the tunnel protection
system and should be approached with caution.
required. They should form the basis of your stud pattern with single, square, flat or angled
backer plates used in between.
Studs should be placed so the pattern does not repeat itself for 4 to 6 pitches.
Transmission
Gear for about IOYO over the actual speed you will run in the race. On grass, your upper sprocket
should be about two teeth smaller than on the ice.
Always stay with the same belt type and size, belt deflection, and center to center distance. Have
several belts of the same size broken in and ready to race. Don't test with one belt and then
"throw on a new one" for race day.
Use a ramp and spring combination to achieve a 5000 RPM engagement. It is best to stay around
4800-4900 unless you know how your tachometer compares to the tech. inspectors tach.
Keep the clutches clean! The pulley faces and belt should be wiped down with acetone before
every run, especially on the grass when pulley and belt temperatures are quite high (you may
even want to ice the pulleys to enhance the cool down process. Just be sure all water is removed
from the pulley surface and then clean them with acetone). Excessive pulley heat indicates belt
slippage and you may need to recalibrate your clutch to "squeeze" the belt harder.
Generally, you will find your quickest elapsed times by setting the clutches to run the engine 200
to 300 RPM below the normal power peak. TEST!!
Tune your clutches so that you run best for the final which means everything will be heat
soaked. If your sled requires different set ups between early runs when everything is cold and
later runs, know what to change and when to change it. Test under a variety of conditions so you
are prepared for any track and race conditions.
Cooling
Install a pair of hydraulic quick couplers in the coolant hoses at a convenient location on the sled.
Make a cooling "cart" using a cooler filled with ice and several winds of copper tubing inside (or
another type of heat exchanger) connected to an electric pump and another set of quick
couplers. Connect your sled to this mobile refrigerator between runs to circulate coolant
through the system and cool the engine down. Cool the engine to the same temperature every
time so your runs are consistent.
Fore more drag racing information contact Bill Rader by fax at (715) 847-6869, phone (715) 847-6884.
Section COMPETITION
07
PREPARATION
07-5