Page 414 - marine
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414
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LOW MODEL SPEED
JET
BN46-42-8002* 120 BN44-40-8067* 120 BN44-40-8052* 100 BN44-40-43 120
SUPER BN SPECS
HIGH NEEDLE ARM LOW SPEED VALVE SPRING SPEED
JET (Grams) ADJUSTER
HIGH SPEED ADJUSTER
CHOKE or PRIMER
Primer Primer Primer Choke Primer Choke Primer Primer
COLOUR
Silver Silver Black Black Silver Black Black Black
POP-OFF PRESSURE
POP-OFF ADJUSTMENT
Super BN Carburetors
Watercraft Parts & Accessories
FUEL
BN38-34-8113*
BN38-34-55-D
BN38-34-8075**
BN38-34-8076**
* Denotes carbs that have extended throttle shafts and can be coupled together as duals. ** Denotes carbs that are designed to be used as a set and can only be used as duals.
115 1.0 1.5 115 1.0 1.5 115 1.0 1.5 115 1.0 1.5
150 2.5 80 1.0 1.5 140 2.5 80 1.0 1.5 125 2.3 65 1.0 1.5 115 1.5 115 1.0 0.75
65 107.5 2.0 65 107.5 2.0 65 107.5 2.0 65 107.5 2.0
The Super BN carbs that come from Mikuni America are already set up for performance applications, and come with pop-o  settings lower than the carbs that come as original equipment.
Pop-o  pressure, (the regulator portion of the Super BN) is a tuneable component of the Super BN and works in conjunction with the low speed jet for good initial throttle response.
The components that make up the regulator portion of the Super BN are: 1. Needle Valve, available in 4 sizes, 1.5, 2.0, 2.3 and 2.5
2. Arm Spring, available in 4 sizes, 115 gr., 95 gr., 80 gr. and 65 gr.
3. Arm
4. Regulator Diaphragm
The arm has a limited range of adjustment; from the arm being level with the adjacent carb surface to being bent upwards no more than .040”
(1 mm) above that surface. If the arm is bent upwards too much, it can cause the needle valve to be held open when the diaphragm and cover are installed. If the arm is bent down, its movement becomes limited and may not be enough to allow the needle valve to open fully.
ADJUSTING POP-OFF PRESSURE
Pop-o  pressure is adjusted by replacing the arm spring with one of a di erent gram rating. Sometimes, in order to achieve the desired pop-o  pres- sure, it is also necessary to change the needle valve size; keep in mind that it’s always best to use the smallest needle valve size to obtain the correct pop-o  pressure.
MEASURING POP-OFF PRESSURE
You can measure pop-o  pressure with a“Pop-o ”pump, available from Mikuni through your dealer, or you can get a relatively good indication of pop- o  pressure by simply using the needle valve and arm spring guide in this manual. Pop-o  pumps are available in three ranges: 0-30psi., 0-60psi. and 0-100psi.. For most performance applications the 0-30psi. pump is appropriate.
Pop-off pressures, in psi, from needle valve size and arm spring combinations
Needle Valve Size
1.5 2.0 2.3 2.5
GOLD 730-03027 115 gr 55 psi
32 psi
22 psi
19 psi
DULL SILVER 730-03027-T 95 gr
43 psi
25 psi
20 psi
17 psi
PRICE LIST ON PAGE 421
BLACK 730-03033 80 gr
38 psi
21 psi
17 psi
14 psi
SHINY SILVER 730-03030 65 gr
32 psi
18 psi
15 psi
12 psi
Pop-Off Arm Spring (colour & strength)


































































































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