"You have a 1957, 5hp made by
"You have a 1957, 5hp made by Gale. It is the same as the Buccaneer, Wards, Goodyears of the same era.
The two other controls are the low and high speed carburetor jets.
Carburetor Adjustment - S/S Adjustable Needle Valve
Initial setting is: Slow speed = seat gently, then open 1-1/2 turns.
Start engine and set the rpms to where it just stays running. In segments of 1/8 turns, start to turn the S/S needle valve in. Wait a few seconds for the engine to respond. As you turn the valve in, the rpms will increase. Lower the rpms again to where the engine will just stay running.
Eventually you'll hit the point where the engine wants to die out or it will spit back (sounds like a mild backfire). At that point, back out the valve 1/4 turn. Within that 1/4 turn, you'll find the smoothest slow speed setting.
When you have finished the above adjustment, you will have no reason to it them again unless the carburetor fouls/gums up from sitting, in which case you would be required to remove, clean, and rebuild the carburetor anyway.
Note: These adjustments are best performed on the boat, where air and water temperatures are similar to normal operation. If performed in a tank, make sure you are ducting or blowing exhaust away from the engine as fumes will circulate back into the air intake and skew your results.
Carburetor Adjustment - H/S Adjustable Needle
Most modern engines are equipped with fixed high speed jets, therefore the following procedure is unnecessary. Yours is not.
This requires 2 people: a driver and a mechanic. If the H/S adjustment has been changed significantly to the point where the engine will not start, commence with the adjustment set at ¾ turn out clockwise from lightly seated – most engines will start at that setting.
With the motor running at full throttle, with the proper size screwdriver or the high speed knob, slowly start turning one of the H/S needles counterclockwise until the engine starts to bog down. Note the position, then turn it back clockwise until the motor misses or threatens to stall. Again, note the position.
At that point, back that needle valve out until the setting is at the mid point of the two settings noted above. You can experiment with fine adjustments and pick the one that (to your ears) has the highest rpm."
