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4.2 Fuel and exhaust systems
Carburettor
-
50 cc Trekker (air-cooled)
Type/lDno.
...............................................
.....................................
Pilot screw initial setting
Floatheight
...............................................
................................................
ldlespeed
................................................
Starterjet
Pilotjet
..................................................
Mainjet
..................................................
Needle (clip position)
.......................................
Carburettor
-
50 cc Vivacity (air-cooled)
Type/lDno.
...............................................
Pilot screw initial setting
.....................................
Floatheight
...............................................
Idlespeed
................................................
Starterjet
................................................
Pilotjet
..................................................
Mainjet
..................................................
Needle (clip position)
.......................................
Carburettor
-
all 100 cc air-cooled engines
Type/lDno.
...............................................
Pilot screw setting
.........................................
Floatheight
...............................................
ldlespeed
................................................
Starterjet
................................................
Pilotjet
..................................................
Mainjet
..................................................
Needle (clip position)
.......................................
Gurtner PA360
1 ! 4 turns out
not adjustable
1500 rpm
45
42
72
L3035H (top notch)
Gurtner PA370
1
!4
turns out
not adjustable
1500 rpm
45
42
72
L3035H (top notch)
Dell'Orto PHVA 17.5
1% turns out
not adjustable
1600 rpm
65
30
83
A1 1 (2nd notch from top)
Torque settings
Carburettor mounting bolts
..................................
8 Nm
Exhaust downpipe bracket bolt
...............................
20 Nm
Exhaust system mounting bolts
...............................
25 Nm
Exhaust manifold-to-cylinder nuts
.............................
16 Nm
Inlet manifold-to-crankcase bolts
..............................
10 Nm
General
precauti
informati
ons
ion and
General information
The fuel system consists of the fuel tank,
fuel tap with integral filter, carburettor, fuel
hose and control cables. In addition, oil for
engine lubrication is fed from the oil tank, via
the oil pump, into the carburettor where it is
mixed with the fuel before entering the engine.
The fuel tap is automatic in operation and is
opened by engine vacuum.
For cold starting, an electrically-operated
automatic choke is fitted in the carburettor.
Liquid-cooled models are fitted with an
external carburettor heater.
Air is drawn into the carburettor through an
intake duct and air filter on the left-had side of
the machine.
The exhaust system is attached to the right-
hand side of the machine.
Many of the fuel system service procedures
are considered routine maintenance items
and for that reason are included in Chapter 1.
Precautions
Warning: Petrol
(gasoline) is
extremely flammable, so take
extra precautions when you work
on any part of the fuel system. Don't smoke
or allow open flames or bare light bulbs
near the work area, and don't work in a
garage where a natural gas-type appliance
is present. If you spill any fuel on your skin,
rinse it off immediately with soap and
water. When you perfom any kind of work
on the fuel system, wear safety glasses and
have a fire extinguisher suitable for a class
B
type fire (flammable liquids) on hand.
Always perform service procedures in a
well-ventilated area to prevent a build-up of
fumes.
Never work in a building containing a gas
appliance with a pilot light, or any other form
of naked flame. Ensure that there are no
naked light bulbs or any sources of flame or
sparks nearby.
Do not smoke (or allow anyone else to
smoke) while in the vicinity of petrol or of
components containing it. Remember the
possible presence of vapour from these
sources and move well clear before smoking.
Check all electrical equipment belonging to
the house, garage or workshop where work is
being undertaken (see the Safety first! section
of this manual). Remember that certain
electrical appliances such as drills, cutters
etc. create sparks in the normal course of
operation and must not be used near petrol or
any
component
containing
it.
Again,
remember the possible presence of fumes
before using electrical equipment.
Always mop up any spilt fuel and safely
dispose of the rag used.
Any stored fuel that is drained off during
servicing work must be kept in sealed
containers that are suitable for holding petrol,
and clearly marked as such; the containers
themselves should be kept in a safe place.
Read the Safety first! section of this manual
carefully before starting work.
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