Rotax Aircraft Engine Bing Carburetors
These informations and much more can be found in our Engine
Maintenance Logs.
Rotax 2-stroke Aircraft Engine Bing Carburetor Configurations
| |
Carburetors |
Intake Silencer |
Main Jet |
Idle Jet |
Needle Jet |
Jet Needle |
Needle Clip |
Air Screw Turns |
| Rotax 277 UL |
1 |
No |
148 |
45 |
2.72 |
8L2 |
2 |
1 |
| 1 |
Yes |
140 |
45 |
2.72 |
8L2 |
1 |
1 |
| Rotax 377 UL |
1 |
No |
165 |
45 |
2.70 |
8O2 |
2 |
½ |
| 1 |
Yes |
155 |
45 |
2.70 |
8O2 |
2 |
½ |
| Rotax 447 UL |
1 |
No |
165 |
45 |
2.70 |
15K2 |
2 |
½ |
| 1 |
Yes |
155 |
45 |
2.70 |
15K2 |
2 |
½ |
| 2 |
No |
135 |
50 |
2.70 |
6G1 |
3 |
1 |
| 2 |
Yes |
128 |
50 |
2.68 |
15K2 |
2 |
1 |
Rotax 503 UL
up
to #3785371 |
1 |
No |
180 |
45 |
2.74 |
8G2 |
3 |
½ |
| 1 |
Yes |
158 |
45 |
2.74 |
6H2 |
3 |
½ |
Rotax 503 UL
after #3785372 |
1 |
No |
185 |
45 |
2.72 |
15K2 |
3 |
½ |
| 1 |
Yes |
165 |
45 |
2.70 |
15K2 |
3 |
½ |
| 2 |
No |
158 |
45 |
2.70 |
11K2 |
2 |
½ |
| 2 |
Yes |
148 |
45 |
2.68 |
11K2 |
2 |
1 |
Rotax 532 UL
582 UL |
2 |
No |
165 |
55 |
2.72 |
11G2 |
3 |
1 |
| 2 |
Yes |
145 |
55 |
2.68 |
15K2 |
2 |
½ |
| Rotax 618 UL |
2 |
No |
160 PTO
170 MAG |
50 |
2.68 |
9M10J |
2 |
1 |
| 2 |
Yes |
135 PTO
145 MAG |
50 |
2.68 |
9M10J |
2 |
1½ |
Adjusting Rotax 2-stroke Aircraft Engine Bing
Carburetors to atmospheric conditions
The fuel/air mixture the carburetor provides to the engine varies with
air density. Air density fluctuates with ambient temperature and altitude
above sea level.
It is sometimes possible to adjust the mixture by changing the position
of the needle clip, but for great variations in atmospheric conditions, a
change of main jet is necessary.
The formula for finding the required main jet is the following:
|
J2 = (D2 / D1) X
J1 |
D1 = Original density
factor
D2 = New density
factor
J1 = Original main
jet
J2 = New main jet
Refer to the chart below to find density factors.
|
| |
m |
0 |
500 |
1000 |
1500 |
2000 |
2500 |
3000 |
3500 |
4000 |
| °C |
°F/ft |
0 |
1600 |
3300 |
5000 |
6500 |
8200 |
10000 |
11500 |
13000 |
| -30 |
-22 |
104 |
103 |
101 |
100 |
98 |
97 |
95 |
94 |
93 |
| -20 |
-4 |
103 |
102 |
100 |
99 |
97 |
96 |
95 |
93 |
92 |
| -10 |
14 |
102 |
101 |
99 |
98 |
96 |
95 |
94 |
92 |
91 |
| 0 |
32 |
101 |
100 |
98 |
97 |
95 |
94 |
93 |
91 |
90 |
| 10 |
50 |
100 |
99 |
97 |
96 |
95 |
93 |
92 |
91 |
89 |
| 15 |
59 |
100 |
99 |
97 |
96 |
94 |
93 |
92 |
90 |
89 |
| 20 |
68 |
100 |
98 |
97 |
95 |
94 |
93 |
91 |
90 |
88 |
| 30 |
86 |
99 |
97 |
96 |
94 |
93 |
92 |
90 |
89 |
88 |
| 40 |
104 |
98 |
96 |
95 |
94 |
92 |
91 |
90 |
88 |
87 |
| 50 |
122 |
97 |
96 |
94 |
93 |
92 |
90 |
89 |
88 |
86 |
For example: your mixture was perfectly adjusted with a 158 main
jet to fly at sea level and a temperature of 20ºC, but you decide to use
your engine in a region at 1500m above sea level and a temperature of
30ºC. What main jet will you need?
J2 = (94 / 100) x 158 =
0.94 x 158 = 148.52
The result is rounded to the next available larger
main jet, in this case 150.
Rotax 4-stroke Aircraft Engine Bing Carburetor Configurations
| |
Main Jet |
Idle Jet |
Needle Jet |
Diffuser |
Jet Needle |
Needle Clip |
Air Screw Surns |
| Rotax 912 UL |
158 |
35 |
2.72 |
961200 |
961215 |
3 |
1½ |
| Rotax 912 ULS |
155 |
35 |
2.70 |
961202 |
961215 |
3 |
1½ |
| Rotax 914 UL |
cyl. 1/3 |
160 |
35 |
2.72 |
961200 |
961215 |
1 |
1½ |
| cyl.2/4 |
164 |
35 |
2.72 |
961200 |
961215 |
2 |
1½ |
| 
