Page last updated July 17, 2008



Carburetor Schematic

Mercury 650 Carburetor Rebuild



Continued from page 1


Here is a diagram of the needle valve inside the bowl and its adjustments and what they should look like before you place back into operation. You may need to bend some of the stainless steel parts in order to get the correct line up. Bend slowly and in small increments.

Bending the primary lever is required in order to get the secondary lever to line up as a straight edge. Grab a pair of needle nose pliers and bend the little "hill" on the primary lever up or down to get the straight edge.

27. Here is a bad photo of me bending primary tab to get the straight edge.

Remove as many parts that can be safely removed. There will be lots of tiny screws / parts so make sure you take pictures and place in an organizer.

If the screw is coated in a red paint like substance, then Mercury has decided that you do not need to remove that particular screw in order to service the carburetor. Everything else should be removed and cleaned with solvent.

Your aim is to remove any varnish like substance that you may find; removal of tiny particles of dirt that have accumulated through time. Floats should be measured and set.

Dirt accumulates inside carburetors through time due to bad seals or no seals in the air intake chambers; bad or dirty fuel filters and various other means.
When you dissassemble the carburetors, it is your aim to find these dirt particles. What is the point if you don't clean. Varnish like substance should be removed with carburetor cleaner. Let the items soak for a while. The varnish like substance / coating is due to fuel being left inside carburetor for long periods of time. To avoid the varnish coat, use fuel stabilzer.



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