Suzuki GS850G Service Manual page 409

HYDROCARBONS
Hydrocarbons are unburned gasoline vapors and can he 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 kilo-
meter. The second method is to measure the concentration of HC in the exhaust gas in parts
per million
IPPM).
The most common cause o f 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 SYSTEM MALFUNCTIONS
1. Spark Plugs
-
Fouled, dirty, improper type or improperly gapped.
2.
Ignition timing
-
Advanced or Retarded.
3. Timing Advance
-
Too fast or too slow an advance rat
4.
Battery
-
Low charge
or faulty,
Carburetion can also lead to high HC emissions if 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-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 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.