2005 Ski-Doo Racing Handbook, Page 322Get this manual
SECTION 06DRIVE SYSTEM
For oval racing, the small benefit you may achieve in top end speed would probably be lost by the loss of acceleration on the start and out of the corners on tight oval circuitThis holds true for cross-country and snow crossers alsoTop speed is not as important as quick acceleration out of the corners and ditchesYou can easily check your gearing selection by marking your drive clutch with black marker with straight lines from bottom to top on the belt surfaces of the clutchGo out and ride your sled under your normal conditions and stop to see how far the belt has rubbed the marker off the clutch surfacesIf it has shifted the belt all the way to the top, you may be able to pull one or two more teeth on the top sprocketExperiment! If it is down about 12 in or more from the top, you could consider trying one tooth smaller top gear depending upon your type of racingThe best combination of gearing for speed and acceleration you can achieve is far more important than shifting the belt all the way to the top of the clutchesThe following formula can be used to calculate the theoretical top speed of your Ski-DooThe formula assumes the transmission is shifted out to its top gear ratioMake sure you use the correct track pitch and transmission ratio for your machineTRA clutch top ratio.83 Pitch of internal drive track2.52 in Number of teeth on internal drive sprocketNOTE: Some Summit and long track models use 10 tooth drive sprockets