Suzuki GS850G Service Manual page 315

HYDROCARBONS
Hydrocarbons are unburnt gasoline vapors and
can be measured
in two different ways. The first i s t o
measure the weight of the pollutants over
a
specific distance such as grams per mile or grams per kilo-
meter. The second method
is
to measure the concentration of HC in the exhaust gas in parts per million
(PPM).
The most common cause of high HC emissions are ignition system problems. If the ignition
system
fails
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 SYSTETvl MALFUNCTIONS
1. Spark Plugs- Fouled, dirty, Impropertypeor improperly 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 t4C emissions i f the mixture i s either excessively rich or excessively
lean.
MIXTURE-RELATED MALFUNCTIONS
1. Air Cleaner
-
Dirty, over oiled or torn.
2. Jets
-
Clogged, restricted or incorrect size.
3.
Float Level
-
Level too
low
(lean) or too high (rich).
4. Choke
-
Leaking choke plunger or sticking linkage.
5. Air Leaks -
Intake manifolds, engine gaskets
and
other sealing surfaces.
6.
Synchronization
-
Unbalanced on multi-cy linder machines.
7.
Exhaust System
-
Restricted flow or improper exhaust system.
Engine wear or damage can also cause high HC emissions,
7 .
Rings
- Low
compression, leakage into crankcase.
2. Valves -
Improper adjustment, bent 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.