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Fix Carburetor fuel over flow

In carburetors, fuel is filled in the carburetor bowl and then supplied to the jets. there is a set level that is maintained to assure a sufficient supply of fuel to the jets. and that level is adjusted by afloat. when the bowl is filled up the float raise and closes the valve that supplies the fuel and then as the fuel is consumed the fuel level drops with it the flot goes down and that opens the fuel valve again to replenish it.


Float Hight is too high: if the float height is too high that will raise the fuel level in the carburetor bowl. if it is raised too high then the fuel will leak into the engine uncontrollably thus causing a rich condition.

too hight float level can also cause fuel to flow from slow jet at wide open throttle. which is not normal.

normally when throttle is pulled beyond 25% the fuel level in float bowel drops which cuts off supply to the piolet jet and when throttle is released the fuel level increases that start back the fuel supply to piolet jet which cause the motorcycle to run at idle.

Float level is too low: if the float level is too low then on high speeds the carburetor bowl won't replenish enough to reach the main jet. this will cause sudden power drop or hick-ups at full throttle. and also if the float height is low then the engine will run leaner and the spark plug color will appear white.

adjustment rules: 

Rule No.1: on most carburetors, the float height is set adjacent to the carburetor body. but float height varies from motorcycle to motorcycle. so always consult the service manual for guidance.

Rule No.2: place the carburetor on the side. float side facing right. then tilt the carburetor to the left at 45 degrees angle. most carburetors are adjusted on this angle because at this angle float is hanging free and you can adjust float height better from this angle.

measuring float angle with protractor

before adjusting float tilt the carburetor to 45 degrees for proper adjustment. or look for the specific angle for your motorcycle carburetor in the service manual.

carburetor float


float valve

Float valve

float valve seat

Float valve Seat

float valve with seat

Float valve Position towards it's seat

float vlave

there is a Groove on the upper side of the float valve for the float to settle

bending float tab

push the tab on the float to decrease the fuel height in carburetor bowel

lifting float tab

lift the tab on the float to increase the fuel height in carburetor bowel

pressing float pin
float pin pressed

there is a dampner on the top of the float valve 

float height too low

adjust the float height where is touches the dampner pin

float height reference point

there is a line that is at the side of the float, for  most carburetors that line is set parellel to the 

float height reference point 2

consult your motorcycle service manual for the correct float height for your motorcycle

float height too low 2d pic

Float height set too low

float height too high 2d pic

Float height set too high

right float height 2d pic

correct float height

right float height

correct float height

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