Piston Wash / Spark Plug Reading; Gasoline Information; Gasoline Volatility - Polaris 340 CLASSIC 2006 Manual

PISTON WASH / SPARK PLUG READING

Changing temperature, barometer, altitude, and fuel supply are
just a few of the factors that can affect the day to day
performance of your engine. That is why using Exhaust Gas
Temperatures (EGT) are important for maintaining optimum
performance. There are two methods for helping you
determine what the EGTs are for your machine. Piston wash
and the coloring of your spark plug.The piston wash is by far
the most valuable tool in concluding EGTs, with the spark plug

GASOLINE INFORMATION

GASOLINE VOLATILITY

One of the misunderstood properties of gasoline is its
volatility, or ability to vaporize at different ambient
temperatures and altitudes during the year.
When gasoline is blended, it is given a Reid Vapor Pressure
(RVP) number which reflects its ability to vaporize or mix
with air at a given temperature range. Gasoline vapor pressure
is measured by putting a sample of fuel inside a closed
container and applying a specified amount of heat to the
color running a distant second. Use the illustrations below to
help you establish the EGTs for your machine.
Once the proper jetting is established, you can reference the
EGT gauge for your baseline numbers. Then, if there is a rise
or fall of 25 degrees, you must jet accordingly to return your
EGTs to the baseline numbers.
container for a certain amount of time. RVP will vary from
about 7.0 PSI during the summer to approximately 13.5 PSI
during the colder months. Service stations selling a large
volume of fuel will normally have the correct blend to work
well at all times throughout the year in their local area.
When the weather is very cold, gasoline must be able to
vaporize very quickly in order for an engine to start and warm
up properly. If summer blend fuel is being used in the winter,
little or no vaporization will occur. Droplets will form causing
flooding and very hard starting.
If winter blend fuel is being used during the summer months, it
may cause vapor lock (boiling fuel) inside the fuel lines, fuel
GENERAL
2.9