
FUEL AND CARBURETOR
6-8
CARBURETOR JETTING
IMPORTANT: The following guidelines must be
followed when establishing a main jet setting:
1. Select the lowest anticipated temperature at which the
machine will be operated.
2. Determine the lowest approximate altitude at which the
machine will be operated.
3. Select the correct main jet according to the engines
fuel/performance requirements.
A main jet that is too small will cause a lean
operating condition resulting in serious engine
damage. Select the correct main jet carefully for
elevation and temperature according to the charts in
the Specifications section or in the Owner’s Safety
and Maintenance Manual for each particular model.
1. Inspect jet needle and needle jet for wear. Look for
discoloration, shiny spots, or an area that looks different than
the rest of the needle. The middle to upper portion of the
needle contacts the needle jet and is the most likely wear point.
If jet needle shows signs of wear replace both the needle and
needle jet to prevent a rich condition.
TIP: A worn needle jet is difficult to spot. To check, slide a
slightly larger new jet needle into the needle jet and hold it to a
light source. Light will be visible between the needle and
needle jet if it is worn.
Pilot Jet
From idling to low speeds, the fuel supply is metered by the
pilot jet. There are several air bleed openings in the sides of the
pilot jet that reduce the fuel to mist. The number stamped on
the jet is an indication of the amount of fuel in cc’s which
passes through the jet during a one minute interval under a
given set of conditions.
Air Mixture Screw
The pilot mixture screw controls the fuel mixture from idle to
low speeds. The tapered tip of the mixture screw projects into
the fuel mixture passage leading to the pilot jet air bleeds. By
turning the screw in or out, the cross sectional area of the air
passage is varied, in turn varying the pilot jet air supply and
changing the mixture ratio.
The airscrew is calibrated at the factory to meet EPA
/ CARB regulations for air quality standards. A
certified repair shop to ensure air quality standards
are not exceeded must perform cleaning of the pilot
circuit.
Summary of Contents for AT56-69E
Page 35: ...MAINTENANCE 2 25 ...
Page 45: ...CVT SYSTEM 3 4 CVT EXPLODED VIEW ...
Page 56: ...ENGINE 4 3 ENGINE ILLUSTRATION ENGINE EXPLODED VIEW ...
Page 57: ...ENGINE 4 4 ...
Page 58: ...ENGINE 4 5 COOLING SYSTEM EXPLODED VIEW ...
Page 59: ...ENGINE 4 6 OIL FLOW DIAGRAM ...
Page 125: ...FUEL AND CARBURETOR 6 15 FUEL TANK SYSTEM ...
Page 135: ...BODY SUSPENSION STEERING 7 6 SUSPENSION ...
Page 142: ...BODY SUSPENSION STEERING 7 13 STEERING ...
Page 151: ...BRAKES 8 6 FRONT BRAKE EXPLODED VIEW MASTER CYLINDER ...
Page 196: ...ELECTRICAL 9 31 WIRE DIAGRAM ...