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Last revised December 28, 2002 11:03 AM (Optimized for IE 5.x, Best Viewed at 800x600)
For friends, family, and all lovers of dirt bikes
The Choke --- When to use it, when NOT to use it
The choke is a seperate circuit within your carberator. If you remove the intake manifold at the mouth of the carb(the side nearest the air box) and look at the outer edge of the carb, you will see a large hole(about the size of a pencil eraser). That is the air jet for the choke cicuit. It acts somewhat like a mini carb inside the carb. Air travels thru that tube and draws fuel thru a different chamber and directs it around the carb slide, it then exits from a small orific on the other side of the slide and is drawn into the engine to burn and create power. The orific is larger than your pilot circuit which allows more fuel to enter the engine, which, As master said, it enrichens the air/fuel mixture. BUT!!!, if you turn the throttle and the cable lifts the slide, it allows too much air to flow under the slide, which in turn creates less negative pressure for the choke circuit to operate. SO, DO NOT TURN YOUR THROTTLE WHEN YOU START A COLD BIKE! By doing this, you bypass the choke circuit and it is like trying to start the bike without one. After the bike starts the choke should be turned off as soon as possible (10-15 seconds at the most). This will prevent a fouled plug by returning the mixture to it's proper ratio. It is very important to warm the bike well (cylinder temp warm/hot, use your hand)prior to take off to prevent a cold seizure (when the piston expands too fast for the cylinder and gets too tight a fit). By using these tips your bike should have a much greater chance of starting without a great deal of effort. If the bike sits for a extended period of time you can use the other tips I suggested in your other post. When I start my bike, I always tip it to one side so fuel spills out of the carb overflow. The fuel level inside the float bowl is raised to allow the mixture to more easily be drawn thru the choke circuit. It also makes sure the fuel in the float bowl is fresh and of good quality. Hope this helps you understand the working's of some of the circuits within your carb.