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MODEL ADJUSTMENT
BS 50-60 Sport 1¾ turns
BS 90STD, 90D, 90T, 90M 1¾ turns
BS 90 Sport 1½ turns
BS 175 DT 1½ turns
(4) With the engine running, adjust idle speed with idle speed adjusting screw
to the lowest RPM possible without stalling engine.
(5) Turn idle mixture screw 1/2 turn in either direction until point is found
where idle RPM is highest.
(6) Re-adjust idle speed screw for best idle speed.
TO ADJUST FLOAT LEVEL:
(1) Remove float bowl cover.
(2) Remove float bowl cover gasket.
(3) Holding carburetor upside down (float valve closed)measure distance between gasket seat and top of
float with a vernier scale. Correct distances are as follows:
MODEL FLOAT LEVEL SETTING
BS 30-60 Sport 25/32 inch
BS 90STD, 90D, 90T, 90M 25/32 inch
BS 90 Sport 23/32 inch
BS 175 DT 23/32 inch
(4) Make adjustments in float level by bending only the brass tab which acts
upon float level. On dual float carburetors, make certain both floats are equal
before setting the float level.
Medium Engine Speeds Adjustment:
The gasoline/air mixture can be adjusted by raising or lowering the jet needle at c - ¾ throttle openings for
medium engine speeds. Standard setting is in the third groove from the top. The throttle valve cutaway also
affects engine operation at below c throttle opening, so do not change throttle valve cutaway for only
medium speeds adjustment.
It is recommended to raise or lower the jet needle for medium engine speeds adjustment within the range
where acceleration is not adversely affected.
High Engine Speeds Adjustment:
The performance of the engine between ¾ and full throttle can be adjusted by changing the main jet. A
higher numbered jet provides a larger orifice and, conversely, a smaller numbered jet provides a smaller
orifice. The jet number appears stamped on the side of the jet.
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