MAINTENANCE
2.13
PILOT SCREW
The pilot system supplies fuel during engine operation with the
throttle valve closed or slightly opened. The fuel/air mixture is
metered by pilot screw and discharged into the main bore
through the pilot outlet.
PILOT SCREW ADJUSTMENT
1. Start engine and warm it up to operating temperature (about
10 minutes).
2. Turn pilot screw in (clockwise) until lightly seated. Turn
screw out the specified number of turns. NOTE: Do not
tighten the pilot screw forcefully against the seat or the
screw and/or seat will be permanently damaged.
3. Connect an accurate tachometer that will read in increments
of + or - 50 RPM such as the PET 2100DX (PN
8712100DX) or the PET 2500 (PN 8712500).
4. Set idle speed to 1200 RPM. Always check throttle cable
freeplay after adjusting idle speed and adjust if necessary.
5. Slowly turn mixture screw clockwise using the pilot screw
wrench until engine begins to miss.
CAUTION
The pilot screw is calibrated at the factory to meet
EPA / CARB regulations for air quality standards
and is sealed with a brass plug to prevent tamper-
ing. Removal of the tamper proof plug is not permit-
ted. For service purposes, cleaning of the pilot
circuit can be done only by a certified repair shop to
ensure air quality standards are not exceeded.
Pilot Screw Location
Brass Plug Installed
Brass Plug Removed
Pilot screws are calibrated at the factory. Each
carburetor has a slightly different pilot screw
setting. The specifications may require
additional tuning to achieve the desired results.
Pilot Screw
FRONT
(Engine)
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