BOMBARDIER 1996 Ski-doo MX Z440 Handbook page 94

Section 03 CHASSIS PREPARATION
Carbide inserted ski runners are necessary for all forms of racing except drag racing and radar
runs. The type of racing you are involved in and the condition of the track will determine what style
of carbide and how much carbide you will be using.
For the ice race track, special flat-backed race runners with 60° carbide inserts are a must. The flat
back of the runner helps to keep the runner from being rolled over by cornering forces. The best
racing runners are heat-treated to prevent them from bending under high side loads.
When installing carbide inserts, start with 100 mm (4 in) of carbide in front of a line projected from
the center line of the ski leg and 125 mm (5 in) behind the line. Always keep the amount of carbide
behind the line longer than in front.
1. 122 mm (5") 98 mm (4")
122 mm (5")
147 mm (6")
171 mm (7") 147 mm (6")
The amount of carbide allowed on each runner may be limited by your race association. Check
your rule book.
Once you have determined how much carbide you will be using, make up at least one more set.
Sharp carbides dig ! They must be sharp enough that when you drag your thumb nail over them,
they will scrape off some of the nail. To keep your carbide runners is this condition, you must
sharpen them every 5 or 6 laps. This is why you should have an extra set ready to go on in a hurry.
The condition of the skis and runners, as well as their alignment, has an effect on top speed. The ski
toe out must be correct; any irregularities in the skis should be removed, and bent or badly worn
runners must be replaced.
Ski runners used for cross-country racing must be selected for the type of conditions you will be
running in. When exposed earth or plowed roads are to be encountered in an event, full length
carbide runners should be used. The concern here is to make the runner and the ski last through
the event. These runners are usually set up with 245 mm (10 in) of 60° carbide in the center of the
bar with the front and rear portions of the bar filled in with 120° carbide inserts.
When the event is held on a lake or surface conditions consist only of snow and ice, a flat-backer
runner with 150 to 200 mm (6 to 10 in) of carbide will do the job. Remember, the more carbide you
install, the more positively the front end steers, but more steering effort is also required. Cross-
country events run for many hours not just a few minutes like an oval event. Match your carbide to
the strength and endurance of your arms.
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