Bing 54 carburetor service, servicing the Bing 54 carburetor used on Rotax two stroke aircraft engines.

Servicing the Bing 54 carburetor used on Rotax aircraft engines.

Maintaining and servicing the Bing  54 Carburetor used on Rotax Aircraft engines. If you check the Rotax maintenance sheet you will find recommendations for servicing the Bing carb at 50 hours and rebuilding them at 100 hours. While this may seem like a daunting task to the "weekend flyer" it is really not that hard to do.

Cleaning the Bing 54 carb, is very easy, and checking for wear is a snap if you know,  where and what to look for.  But in most cases pilots will not be servicing the carb(s) because of use - mainly it will be from lack of use or improper storage!  

In fact if the engine has been stored improperly it may be necessary to replace the carb(s) which can be very expensive - or rebuilding them which is considerably cheaper.

The first thing you'll need to rebuild your carb is a carb rebuild kit. 
You'll need one rebuild kit for each carb. Here is a list of the parts that are included in the carb rebuild kit:

Top O Ring - this larger O ring  goes under the top of the carb  this seals the carb and prevents air from entering and leaning the mixture out.
Air Screw O Ring - this O ring that seals the idle air mix screw, and helps lock it in place so it does not go out of adjustment
Bowl Gasket-  gasket seals the float bowl to the body of the carb, keeping the fuel in and air out.
Needle valve -  small valve, and even smaller spring clip which controls the flow of fuel into the float bowl.
Hinge Pin - the float arms ride on this pin, and signs of wear will show up on the pin.
Sieve Sleeve  - this stops foam from entering the main jet, that is when you pass foam through a screen like this it turns back into liquid
Cable Grommet - the grommet prevents water from entering the top of the carb via the throttle cable and following it down into the float bowl.These are the parts that wear over a period of time, and need to be  replaced. This wear can cause your float bowl to leak or overflow, provide an improper fuel mixture to your engine, or allow air or water to enter your carburetor(s).

While it is possible to clean your main jets, idler jets, replacement is the better choice if they are badly "gunked up" or have a lot of hours on them. The jet holes are used to "meter" fuel into the engine, over time these can become enlarged, with the passage of fuel through them, giving you a rich mixture. 

Or if they have been clogged up they can lean the mixture out. In a recent test case main jets from a 582 Rotax engine with 368 hours on it were measured against new - the jets with 368 hours on them were 4% larger than the new ones. 

While the low speed or idle jets were 7% smaller.

The needle jets, jet needles, and clips are also an area of concern. A number of pilots have had accidents when their engines have failed or lost power in flight when needle/clip have failed and the needle has dropped down into the main jet blocking off the fuel.  These are replacement items if found to be worn. If they are the older style they should be updated!

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The floats in the Bing carb have also been updated, with the new system having two separate floats rather than two floats joined together on a float arm. The new floats should be examined for damage around the area where the pin guide goes through the center of the float. 

They should also be checked for floatation. To do this fill you float bowls about 3/4 full and place the floats on their pins. Allow them to sit for about 30 minutes and then check to see if they  are both level with each other.

On older model carbs there were two vent tubes, one coming out each side of the unit. The latest carbs have one vent tube connected to the two venting outlets - with breather holes in the center section of the vent tube.

Apparently in the older style of venting system air could enter one vent line and exit the other causing havoc with the float metering system. The new system prevents this giving a more stable fuel supply.

This new style of vent can be made from a piece of primer line and putting two side by side holes in the BOTTOM of the line in the center, these holes are about 30% of the diameter of the primer line. Too small and they will not allow the carb to breath properly.