Harley Davidson Touring Service Manual & H-D Touring Electrical Diagnostic Manual for models: FLHTCUI Ultra Classic Electra Glide, FLHTC/FLHTCI Electra Glide Classic, FLHT Electra Glide Standard, FLHTCUI Ultra Classic Electra Glide, FLTR/I Road Glide, FLHRCI Road King Classic, FLHR Road King, FLT Police Models Service Manual Supplement and FLTRSEI2 Model Service Manual Supplement. FLHTCUI, FLHTC, FLHTCI, FLT, FLHT, FLHTCUI, FLTR, FLTRI, FLHR, FLTRSEI2.
Inspect spark plugs at 5000 miles (8,000 km) and replace at
10,000 miles (16,000 km).
The number plug is supplied as original equipment and
is the only plug that should be used. The resistor plug
reduces radio interference created by the ignition system and
will not adversely affect performance or fuel economy.
1. Remove spark plug cables. See SPARK PLUG CABLES
on the next page.
2. Remove spark plug using a 5/8 inch spark plug socket.
See Figure 8-6. Examine plugs as soon as they have been
removed. The deposits on the plug base are an indication of
the plug efficiency and are a guide to the general condition of
rings, valves, carburetor and ignition system.
a. A wet black and shiny deposit on plug base, electrodes
and ceramic insulator tip indicate an oil
fouled plug. The condition may be caused by worn
rings and pistons, loose valves or seals, weak battery
or faulty ignition.
b. A dry fluffy or sooty black deposit indicates a too
rich carburetor air-fuel mixture or long periods of
engine idling. Excessive use of the enrichener may
also cause this condition.
c. An overheated plug can be identified by a light
brown, glassy deposit. This condition may be
accompanied by cracks in the insulator or by erosion
of the electrodes. This condition is caused by
too lean an air-fuel mixture, a hot running engine,
valves not seating or improper ignition timing. The
glassy deposit on the spark plug is a conductor
when hot and may cause high speed misfiring. A
plug with eroded electrodes, heavy deposits or a
cracked insulator should be replaced.
d. A plug with white, yellow or light tan to rusty brown
powdery deposit indicates balanced combustion.
The deposits may be cleaned off at regular intervals
Tags: Spark Plug, Spark plugs, Spark Plug Gap, Spark Plug Type