How to Set Float Height on an XS650
The Yamaha XS 650 is a 654 cc motorcycle was produced from 1968 to 1985. There were two types of carburetors used on the XS 650, but the float adjustment procedure is the same for both. The carburetor float works in conjunction with the fuel needle and seat to control the amount of fuel that enters the float bowl. As fuel enters the bowl through the needle and seat, the float rises. A tab on the float rests against the fuel needle and shuts off the fuel flow at a certain point. If the float is set too low, the engine can starve for fuel. If it is set too high the engine might get flooded. This article assumes that the carburetors are already removed from the XS 650.
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Things You'll Need
- Carburetor cleaner
- Drain pan
- Wrench set
- Phillips screwdriver
- Paper clip
- Needle nosed pliers
Instructions
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1
Spray the body of each carburetor with carburetor cleaner to remove any dirt or grime from the carburetor.
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2
Hold the carburetor over a drain pan. Use a wrench to remove the drain plug from the side of the fuel bowl. Catch any fuel that pours out of the hole in the drain pan. Turn the carburetor upside down and use a Phillips screwdriver to remove the four Phillips screws that hold the fuel bowl onto the carburetor body. Remove the fuel bowl.
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3
Look at the flat gasket surface on the carburetor body, while inverted, where the fuel bowl seats. You will see the bottom of the float rising above the gasket surface. Keep in mind that the carburetor is upside down. The bottom of the float is flat. The flat surface of the float should be parallel to the gasket surface on the carburetor body. If not, the float needs to be adjusted.
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Adjust the float by pushing out the float pivot pin with a paperclip. Remove the pin and float. The float has a metal tab that rests on the fuel needle. The tab is between the holes that the pivot pin slides through. If the float is too low, use needle nosed pliers to carefully bend the tab down toward the needle. If it is too high, bend the tab up, away from the needle. Replace the float and pivot pin and check the float height. It might take more than one try to get it right. Repeat for the other carburetor.
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References
- "Haynes Motorcycle Fuel Systems Techbook"; John Robinson, 2000
