Choke That Engine
While I will continue to refer to the carburetor starting equipment as a choke they are actually a system of richer jets that provide the needed extra fuel to allow the starting and cold-running of the engine.
When starting a bike cold, it works best to fully engage the choke and leave the throttle CLOSED. Opening the throttle upsets the vacuum differential needed for the proper operation of the choke.
Once the bike starts and catches on all the cylinders, ease the choke off a bit to allow the motor to idle up. Depending on the particular bike, you should be able to now drive away after a brief warm up period. Ease the choke off as the bike will run without it, not forgetting to shut the choke off completely as soon as the bike no longer needs it. The length of time needed for application of the choke will become apparent as too quickly taking off the choke will cause hesitations and too long a time with the choke on will load up the motor, generally showing itself as a misfire the first full power application that goes away shortly afterwards. Experimenting with this rate of application will soon show how to get the best behavior characteristics of the individual bike.
Having to run the bike with the choke on to get it to run properly when fully warmed up is generally a sign of carburetor or air leak problems and should be addressed by a competent facility.
Hope this takes some of the mystery out of cold-motor starting.
Source: http://www.motorcycleperf.com/techti...0Operation.htm




