Recommended Jetting Chart - Bing Carbs

Reprinted by permission of David loveman

The following is the factory recommended jet for Bing carburetors at sea level and 70F degrees. Apply the Bing Main Jet Correction Chart shown at the bottom of the page to compensate for temperature and altitude at your location.

Rotax Engines w/o Intake Silencer

Engine Type Main Idler Needle Jet Clip AirScrew
  Jet Jet Jet Needle from top
Rotax 277 148 45 2.72 8L2 2 1.0
Rotax 377 165 45 2.70 8O2 2 0.5
Rotax 447 165 45 2.70 15K2 2 0.5
Rotax 447 DC 135 50 2.70 6G1 3 1.0
Rotax 503 SC
Up to Serial #3785371		 180 45 2.74 8G2 3 0.5
Rotax 503 SC
After Serial #3785372		 185 45 2.72 15K2 3 0.5
Rotax 503 DC 158 45 2.70 11K2 2 0.5
Rotax 532 SC 195 55 2.74 15K2 3 1.0
Rotax 532/582 DC 165 55 2.72 11G2 3 1.0
Rotax 618 DC 158 55 2.72 15E5U 3 1.0

Rotax Engines with Intake Silencer

-NOTE-
I personally do not recommend the use of the intake silencer
it reduces horsepower and is generally ineffective in noise reduction !

Engine Type Main Idler Needle Jet Clip Airscrew
  Jet Jet Jet Needle  
Rotax 277 140 45 2.72 8L2 2 1.0
Rotax 377 155 45 2.70 8O2 2 0.5
Rotax 447 155 45 2.70 15K2 2 0.5
Rotax 447 DC 128 50 2.68 15K2 2 1.0
Rotax 503 SC
UP to Serial #3785371		 158 45 2.74 6H2 3 0.5
Rotax 503 SC
After Serial #3785372		 165 45 2.70 15K2 3 0.5
Rotax 503 DC 148 45 2.68 11K2 2 1.0
Rotax 532 SC 170 55 2.74 15K2 3 1.0
Rotax 532/582 DC 145 55 2.68 15K2 3 1.0
Rotax 618 DC 135 55 2.70 15E5U 3 1.0


Bing Correction Chart

 How to Use the Bing Main Jet Correction Chart

Step #1 - Assume Nothing!!! (ASSUME-makes an ASS out of U and ME) -Disassemble and check your carburetor(s) to verify the recommended jetting listed in the recommended Bing jetting chart is installed in your Carb(s). This is the most up to date information available at the time of this publication.

Step #2 - Because air density varies with temperature and altitude changes, a main jet correction may be necessary. This chart was calculated at sea level with an air temperature of 60F or 15C.

Step #3 - Apply the multiplication factor shown to the main jet size recommended in the chart at the top of the page.

Step #4 - Your operating conditions will vary by the change of seasons. If your EGT T temps vary and your engine experiences performance difficulties, a review of your jetting may be necessary. Return to step #2.

Step #5 - Humidity is also a variable in determining air density. A high humidity means a lower air density of air to be consumed by combustion. Because we are generally not equipped with a way of easily reading the % of humidity present, this can be read in to this chart by adding altitude on high humidity days and subtracting altitude on in very dry climates. An EGT gauge should illustrate changes in these conditions under lull throttle readings.


Main Jet Correction Chart ................ Example: 160 x 0.89= 142 Main Jet

Altitude - Meters 0m 500m 1000 1500 2000 2500 3000 3500 4000
- Feet 0' 1500' 3000' 4500' 6000' 7500' 9000' 10500' 12000'
Temperature                  
-22F -30C 1.04 1.03 1.01 1.00 0.98 0.97 0.95 0.94 0.93
-4F -20C 1.03 1.02 1.00 0.99 0.97 0.96 0.95 0.93 0.92
14F -10C 1.02 1.01 0.99 0.98 0.96 0.95 0.94 0.92 0.91
32F 0C 1.01 1.00 0.98 0.97 0.95 0.94 0.93 0.91 0.90
50F 10C 1.00 0.99 0.97 0.96 0.95 0.93 0.91 0.90 0.88
59F 15C 1.00 0.99 0.97 0.96 0.94 0.93 0.92 0.90 0.88
68F 20C 1.00 0.98 0.97 0.95 0.94 0.93 0.91 0.90 0.88
86F 30C 0.99 0.97 0.96 0.94 0.93 0.92 0.90 0.89 0.88
104F 40C 0.98 0.96 0.95 0.94 0.92 0.91 0.90 0.88 0.87
123F 50C 0.97 0.96 0.94 0.93 0.92 0.90 0.89 0.88 0.86

Note:
Before operating the engine again at lower altitudes, reinstallation of the original jetting is necessary or engine damage or failure may occur!

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