Suzuki GS850G Service Manual page 446

HYDROCARBONS
Hydrocarbons are unburned gasoline vapors and can be measured in two different ways, The first is to
measure the weight
of the pollutants over
a
specific
distance such as grams
per mile or grams per kito-
meter.
The second method is
to
measure the concentration of HC in t h e exhaust gas in parts per million
{PPM).
The most common cause of high HC emissions
are
ignition system problems. If the ignition system f a i l s
to ignite
the fuel mixture properly, then raw
gasoline vapors will pass through the engine into the ex-
haust system. Listed are the most common ignition problems which occur and which can affect HC
emission
output.
IGNITION SYSTEIvI MALFUNCTIONS
1, Spark Plugs
-
Fouled, dirty, improper
t y p e
or improper1
y
gapped,
2, Ignition
timing
-
Advanced or Retarded.
3.
Timing Advance
-
Too fast or too
slow an advance rate.
4. Battery
-
Low charge or faulty.
Carburetion can also lead
to
high HC emissions i f the mixture is either excessively rich or excessively
lean.
MIXTURE-RELATED MALFUNCTlONS
1. Air Cleaner
-
Dirty,
over
oiled or torn.
2. Jets
-
Clogged, restricted or
incorrect
size.
3.
Float Level
-
Level too low (lean) or too h i g h (rich).
4. Choke
-
Leaking choke plunger or stick
Eng
linkage.
5. Air Leaks
-
l ntake
manifolds, engine gaskezs and other sealing surfaces.
6. Synchronization
-
Unbalanced on multi-cylinder machines.
7.
Exhaust System
-
Restricted flow
or improper
exhaust system
Engine wear or damage can also cause high HC
emissions.
1. Rings
-
Low compression, leakage
into
crankcase.
2. Valves
-
Improper acljustment, P~ent
stem or burnt.
3.
Gaskets
-
Leaking, loss of compression.
4. Crank Seals
-
Leaking.
5. Oil Consumption
-
Worn valve guides, worn rings, clogged crankcase breather.
6. Oil -
Improper engine oil.