2005 Ski-Doo Racing Handbook, Page 141Get this manual
SECTION 05ENGINE PREPARATION
Starting Device (enrichner)
Instead of choke, the enrichner system is used on some Mikuni carburetorsIn the starter type, fuel and air for starting the engine are metered with entirely independent jetsThe fuel metered in the starter jet is mixed with air and is broken into tiny particles inside the emulsion tubeThe mixture then flows into the plunger area, mixes again with air coming from the air intake port for starting and is delivered to the engine in the optimum air fuel ratio through the fuel discharge nozzleThe starter is opened and closed by means of the starter plungerSince the starter type is constructed so as to utilize the negative pressure of the inlet pipe, it is important that the throttle valve be closed when starting the engineSelection of the Aperture of Carburetor
One of the prerequisites for improving the output is to use carburetor with as large an aperture as possibleHowever, large aperture alone does not necessarily improve the outputAs shown in the following illustration, it is true that large aperture improves the power output in the high speed rangeIn the slow speed range, on the other hand, the output dropsThe aperture of carburetor is determined by various factorsThese factors include (1) whether the vehicle is intended for racing, (2) the design of the engine, (3) driving technique of the driver, (4) the driver's preference, etcIn addition, the maximum output, the maximum torque and the minimum number of revolutions for stable engine operation must also be taken into accountToo large an aperture Proper aperture