Curtis Dyna-Fog BLACKHAWK 2620, Instruction Manual

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*CARBURETOR
The Carburetor on this machine does not need frequent adjustment or servicing. (However,
a change in air density will have an affect on the carburetor setting. Altitude, atmospheric
pressure, and temperature, all interact to affect air density. A “rule of thumb” is: as
temperature decreases, the amount of fuel needed for the engine to operate increases.)
Careful attention to putting only clean gasoline in the machine will significantly reduce trouble with
the Carburetor. The Carburetor idle-needle is pre-set at the factory for the correct fuel at an altitude
of approximately 1000 feet (305 meters). Minor adjustment of the needle may be required for high
altitude. When the Carburetor is set at the nominal setting, as explained below, performance
difficulties will usually be found to be caused by sources other than the carburetor. For example, if
the engine dies or runs rough, carbon build-up in the engine neck will often be found to be the
cause. Scheduled cleaning as detailed in MAINTENANCE will eliminate this cause.
*IDLE NEEDLE ADJUSTMENT
NOTE
Read the entire CARBURETOR section before performing the idle needle adjustment.
1. Drain any formulation remaining in the Formulation Tank.
2. Add approximately 1 quart (1 liter) of flushing solution or water, instead of fuel oil, to the
Formulation Tank.
3. Make sure the Fuel Tank has gasoline in it and the 3-way selector valve is in the purge position.
4. With the engine stopped, turn the idle-needle screw gently clockwise (CW) until the needle
seats.
CAUTION
Do not over-tighten the idle-needle. Over-tightening may damage the
carburetor.
5. After the needle seats, turn the idle-needle screw counterclockwise (CCW) one-half (1/2) of one
revolution.
WARNING
IF THE MIXTURE IS TOO LEAN, THE ENGINE MAY DIE AT THIS POINT. UPON
RESTARTING, FLAME MAY MOMENTARILY SHOOT OUT THE DISCHARGE TUBE.
FIGURE 7
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