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FAT
BOY
Harley-Davidson released a motorcycle in 1990 based on the FLST
Heritage Softail. They called it the FLSTF or Fat Boy and it
is immediately recognized by its solid cast disc front wheel.
FATHEAD
The Twin-Cam engine (V-Twin, produced from 1999 – Current
Day)
FLATHEAD
The Flathead engine (V-Twin, produced from 1929 – 1972)
FLOW RATE METER
Device used in many injection systems.
FOUR-STROKE
ENGINE
This is the most common engine design found in street motorcycles
today. It refers to the number of times a piston moves up and
down through each power cycle. 1) A downward stroke brings in
the fuel/air mixture; 2) an upward stroke compresses the fuel/air
mixture; 3) a downward stroke results when that mixture is ignited
and expands, and finally; 4) an upward stroke expels the exhaust
gases.
FRESH
GAS
The fresh mixture drawn into the cylinder ia a combination of fresh
air and the fuel entrained with it. While most of hte fresh air
enters through the throttle valve, supplementary fresh gas can
also be drawn in through the evaporative-emissions control system.
FUEL
ACCUMULATOR
The fuel accumulator maintains the pressure in the fuel system
for a certain time after the engine has been switched off in order
to facililate restarting, particularly when the engine is hot.
The special design of the accumulator housing is such that it deadens
the sound of the electric fuel pump. FUEL CELLS
FUEL
CONSUMPTION
The effects of timing advance on fuel consumption are the exact opposite of its
influence on emissions. If the combustion sequence is to remain optimal at higher
excess-air factors (lambda), then ignition timing must be advanced to compensate
for the slower combustion rate. Thus advanced ignition timing means lower fuel
consumption and more torque.
FUEL
DELIVERY
The electric fuel pump continuously pumps fuel from the tank and through the
fuel filter to the central injection unit. Fuel pumps are avaible as in-line
or in-tank versions.
FUEL
DISTRIBUTOR
Depending upon the position of the plate in the air-flow sensor,
the fuel distributor meters the basic injection quantity to the
individual engine cylinders. The position of the sensor plate is
a measure of the amount of air drawn in by the engine. The position
of the plate is transmitted to the control plunger by a lever.
FUEL
FILTER
The fuel filter retains particles of dirt which present in the
fuel and which would otherwise have an adverse effect on the functioning
of the injection system. The fuel filter contains a paper element
with a mean pore size of 10 hm backed up by a fluff trap. This
combination ensures a high degree of cleaning.
FUEL
FILTRATION
Fuel-borne contaminants and impurities can prevent the injectors
and fuel-pressure regulator from operating correctly. Afilter is
therefore fitted in the fuel line between the electric fuel pump
and the central injection unit, preferably in a position underneath
the vehicle protected agaisnt stone-throw.
FUEL INJECTION
On internal-combustion engines, a system that injects a precisely
measured amount of fuel into the cylinder at exactly the right
moment. Dispenses with the carburetor and increases engine
efficiency. Fuel injection provides better metering of fuel
and air than carburetors. This results in more power, improved
fuel economy, and lower emissions. The simplest systems use
single or dual injectors in a central chamber to supply all
cylinders. More sophisticated systems use an injector at each
cylinder to precisely meter fuel.Any system that meters fuel
to an engine by measuring its needs and then regulating the
fuel flow, by electronic or mechanical means, through a pump
and injectors. Throttle-body injection locates the injector(s)
centrally in the throttle-body housing, while port injection
allocates at least one injector for each cylinder near its
intake port.
FUEL LINES
Fuel lines must be installed so that they cannot be asversely effected
by torsional motion, engine movement, or similar, phenomena.
FUEL
METERING
The task of the fuel-management system is to meter a quantity of
fuel corresponding to the intake air quantity. Basically, fuel
metering is carried out by the mixture control unit. This comprises
the air-flow sensor and the fuel distributor.
FUEL-PRESSURE
ATTENUATOR
The injectors operating cycles and the periodic discharge of fuel
that characterizes the postive-displacment fuel pressure. Under
unfavorable circumstances, the mountings for the electric fuel
pump, fuel lines and fuel rail can transmit these vibrations to
the vehicle's body.
FUEL-PRESSURE
REGULATOR
The injected fuel quantity should be determined exclusively by
injection duration. Thus the difference between the fuel-pressure
in the fuel rail and the pressure in the intake tract must remain
constant. A means is thus required for adjusting the fuel pressure
to reflect the variations in the load-sensitive manifold pressure.
The fuel-pressure regulator therefore regulates the amount of fuel
returning to hte tank so that a constant pressure drop is maintained
across the injectors. With multipoint injection, the pressure regulator
is generally positioned at the far end of the fuel rail to avoid
impairing the flow within the rail. However, it can also be mounted
in the fuel return line.
FUEL
PUMP DEGASSER
Degasatore pompa carburante Device fitted to the fuel system
downstream from the pump.
FUEL RAIL
Contaminants in the fuel can impair the operation of both pressure
regulator and injectors. A filter is therefore installed downstream
from the electric fuel pump. This fuel filter contains a paper
element featuring a mean pore diameter of 10hm. A blackplate retains
it in its housing. The replacement intervals are determined by
the filter's volume and contamination levels in the fuel.
FUEL
SYSTEM
The fuel-supply system must be capable of providing the engine
with the required quantity of fuel under all operating conditions.
An electric pump draws the fuel through a filter while extracting
it from the tank for delivery to the fuel-distribution rail with
its electromagnetic injectors . The injectors spray the fuel into
the engine's intake tract in precisely metered quantities. The
excess fuel flows through the pressure regulator and back to the
fuel tank.
FUEL
TANK
According to the German equivalent of the FMVSS/CUR, the fuel tank
must be corrosion-resistant and not leak even at a pressure defined
as double the normal operating pressure, but al least at 0.3 bar
overpressure. Suitable openings, safety vavles etc. must be provided
to permit excess pressure to escape. Fuel must not escape past
the filler cap, nor through the pressuree-qualization devices.
This also applies in the case of roas shocks, or in curves, or
when the vehicle is tilted. The fuel tank must be remote from the
engine so that the ignition of the fuel is not to be expected even
in the event of an accident. Further, more stringent regulations
apply in the case of vehicles with open cabs, and for tractors
and buses.
FULL-LOAD ENRICHMENT
The engin delivers its maxium torque at full load, when the air-fuel
mixture must be enriched compared to that at part-load. In contrast
to part-load where the calibration is for minimum fuel consumption
and low emissions, at full load it is necessary to enrich the air-fuel
mixture.
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