Why your F3 runs better with the choke on:
#1
09-28-2009, 02:52 AM
Why your F3 runs better with the choke on:
"Help! my bike won't idle unless my choke is on"
http://web.ncf.ca/ag136/cvCarb.jpg
I'm sure you have looked down your carbs before and seen the black slides that cover up the entire intake. Even when you turn the throttle they don't move! You can't see the choke when you move the lever either, what gives?
http://media.photobucket.com/image/c...t/DSC00811.jpg
Our motorcycles have CV carbs that have vacuum operated slides. When the engine is running, the amount of vacuum in the throttle bodies is directly related to how much the throttle is opened, and the slides float up because of air pressure.
There are jets/fuel passages in each of your carburetors, the low speed jet the Main jet, and an idle circuit.
On traditional carbs, the choke blocks the intake of the carb off. On CV carbs the choke just dumps fuel right in the throttle body past the slide. A better name for our choke could be a "flood"! It just lets the gas right in.
At low RPM and Idle, the low speed/idle circuit delivers fuel to the engine. When these get clogged/dirty/ gummed up, less fuel can flow through them and your engine leans out. This can result it the engine not starting or idling, sometimes the bike feels just fine at WOT, but it dies when you turn the throttle too quickly.
When you open up the choke, the fuel flows right into the throttle body, past the slides and into the engine. In many cases this is enough fuel to keep the engine alive and you can actually ride the bike (somewhat)
If it runs with the choke on, more often than not it means your idle jet/circuit is dirty and you need to clean the carburetors and get them synchronized!
Now you know why!
Good luck and safe riding!
http://web.ncf.ca/ag136/cvCarb.jpg
I'm sure you have looked down your carbs before and seen the black slides that cover up the entire intake. Even when you turn the throttle they don't move! You can't see the choke when you move the lever either, what gives?
http://media.photobucket.com/image/c...t/DSC00811.jpg
Our motorcycles have CV carbs that have vacuum operated slides. When the engine is running, the amount of vacuum in the throttle bodies is directly related to how much the throttle is opened, and the slides float up because of air pressure.
There are jets/fuel passages in each of your carburetors, the low speed jet the Main jet, and an idle circuit.
On traditional carbs, the choke blocks the intake of the carb off. On CV carbs the choke just dumps fuel right in the throttle body past the slide. A better name for our choke could be a "flood"! It just lets the gas right in.
At low RPM and Idle, the low speed/idle circuit delivers fuel to the engine. When these get clogged/dirty/ gummed up, less fuel can flow through them and your engine leans out. This can result it the engine not starting or idling, sometimes the bike feels just fine at WOT, but it dies when you turn the throttle too quickly.
When you open up the choke, the fuel flows right into the throttle body, past the slides and into the engine. In many cases this is enough fuel to keep the engine alive and you can actually ride the bike (somewhat)
If it runs with the choke on, more often than not it means your idle jet/circuit is dirty and you need to clean the carburetors and get them synchronized!
Now you know why!
Good luck and safe riding!
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