Why Do Two Coolant Lines Go To My Carb?
Why do two coolant lines go to my carburetor? Can I get rid of them?
If you have tried to remove the single carb from your bike, you may have noticed 2 coolant lines that come from the motor and attach to a little "Y" shaped junction. This junction is a dead end, it does not go into the carb. Coolant is passed through a small dead end on the backside of the single carb Honda shadow. This is done not to cool the carburetors, but to heat them. The idea is to prevent the formation of ice in the carburetor throat as fuel is evaporated. Fuel evaporation can cause extreme temperature decreases in the throat of the carburetor. During particularly humid and cool weather conditions, such as riding in clouds or fog, ice could form in the carburetors and prevent the engine from running.
That is the theory. In practice, this rarely happens. There is also a downside to this carb heating. At upper elevations and at high temperatures, the heating of the carbs can be excessive and actually cause the fuel to boil preventing the engine from running. While I have neither heard of nor experienced any instances of carb icing on the Honda Shadows, there have been many reports of this condition arising.
You can remove the coolant lines from your carburetor. Just unscrew that little junction and pull it out of your carb. You can then connect the line going from your radiator to the intake manifold or you can plug them. If you choose to plug them remember those ports are under pressure so you can't just use a vacuum plug. A simple method is to use a large bolt threaded into the hose then hose clamp around the bolt so it cant back out.