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BP-017 · Carburettor
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1
1
2
2
3
3
4
4
5
5
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8
A
A
B
B
C
C
D
D
E
E
F
F
104
87.5
Ø26
64
20
22
21
10
24
1
3
4
25
2
8
9
23
15
5
7
6
11
B
D
C
AXIAL SECTION
THROUGH THE BORE · SCALE 2:1
6.03
18
19
17
16
DETAIL B
FLOAT NEEDLE VALVE · SCALE 5:1
0.47
12
13
14
DETAIL D
IDLE AND PROGRESSION PORTS · 5:1
Ø41
64
26
VIEW C
FROM THE AIR HORN · SCALE 1:1
4
6
8
10
12
14
16
18
20
22
0
10
20
30
40
50
60
70
80
THROTTLE θ FROM THE STOP, °
AIR–FUEL RATIO, kg/kg
DIAGRAM 1
ACCENT: MIXTURE · THIN: MAIN JET ALONE · DASHED: CHOKE SHUT · CHAIN: 14.7
0
5
10
15
20
25
0
4
8
12
16
20
0.0
0.4
0.8
1.2
1.6
AIR FLOW, g/s
THROAT Δp, mbar
FUEL, g/s
DIAGRAM 2
THIN: Δp = ½ρv² AT THE THROAT · ACCENT: FUEL · CHAIN: AIR/14.7
NOTES
1. BERNOULLI: THROAT Δp = ½ρv²; THE BOWL IS VENTED, SO Δp LIFTS THE FUEL.
2. MAIN JET FLOWS ONCE Δp > ρgh = 44 Pa (h = 6 mm, LEVEL TO BLEEDS).
3. BELOW THAT, THE PILOT CIRCUIT: IDLE PORT, THEN 2 PROGRESSION PORTS.
4. 250 cm³ SINGLE, η 0.85, ROAD LOAD 1400–9000 rpm; PETROL 740 kg/m³.
ITEM
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26
DESCRIPTION
BODY, Ø26 BORE, Ø20 VENTURI
FLOAT BOWL
BOWL GASKET 0.8
SCREW M4×10 ISO 7045
DRAIN PLUG M10×1.25
SEALING WASHER 10×14×1
MAIN JET #135 M6×0.75
EMULSION TUBE, 6× Ø0.8 BLEEDS
MAIN NOZZLE Ø5×2.6
MAIN AIR JET Ø0.7
PILOT JET #35 M5
PILOT AIR JET Ø1.6
MIXTURE SCREW M5×0.5, 10°
SCREW SPRING Ø6, 3 TURNS
FLOAT, HOLLOW, 0.8 WALL
FLOAT ARM 0.8
HINGE PIN Ø2×12
FLOAT NEEDLE, FKM TIP
NEEDLE SEAT M6×0.75, Ø1.5
CHOKE PLATE 0.8, 2× Ø6.5
CHOKE SPINDLE Ø4
THROTTLE PLATE Ø26.1×1.2
THROTTLE SPINDLE Ø5
BALL PLUG Ø2
BOWL VENT TUBE Ø4×0.5
FUEL INLET NIPPLE Ø6
MATERIAL
EN AC-46000 DIE CAST.
EN AC-46000 DIE CAST.
NBR 70
STEEL 4.8, ZINC
CuZn39Pb3
Cu-ETP
CuZn39Pb3
CuZn39Pb3
CuZn39Pb3
CuZn39Pb3
CuZn39Pb3
CuZn39Pb3
X10CrNi18-8
EN 10270-1 Ø0.5
POM-C
CuZn37 R350
X10CrNi18-8
X46Cr13
CuZn39Pb3
CuZn37
X10CrNi18-8
CuZn37
X10CrNi18-8
100Cr6
CuZn37
CuZn37
QTY
1
1
1
2
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
2
1
1
TITLE
CARBURETTOR · AXIAL SECTION
DWG NO
BP-017
SCALE
2:1
SIZE
A2
SHEET
1 / 1
DRAWN
CLAUDE
DATE
2026-10-15
MATERIAL
SEE PARTS LIST
GENERAL TOL.
ISO 2768-m
UNITS
mm · g/s · mbar
LIVE · DRAG THE PLATE · ← → THROTTLE · C CHOKE · [ ] MIXTURE SCREW
Drag the throttle plate ·
←
→
throttle ·
C
choke ·
[
]
mixture screw ·
S
slow
blueprint
paper
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