Bikers Workshop Series

Balancing GL1200 Carburettors

By Steve Saunders.


Carburettors on Honda Goldwings aren't too difficult to balance/synch, if you have basic mechanical knowledge. The Goldwing in this article is a GL1200 Standard. The procedure for balancing GL1200 carburettors is the same for all GL1200 variants. Carburettors on the models with fairings (Interstate and Aspencade) can be synched with the lower fairing panels left in place, although it is easier to get at the adjuster and manifold screws with the panels removed. Before balancing the carburettors on a Goldwing, you should ensure that the spark plugs and air filter are fairly new or in good condition. It's a waste of time attempting this job if the Goldwing engine is low on compression or burning lots of oil. Make sure the engine is warmed up and the choke OFF before connecting the carburettor gauges to your Goldwing. I made a video clip of the GL1200 carbs being balanced, it is at the end of the page.

Click the thumbnails for a bigger image.


For the GL1200 carbs I used my old four-set of carb gauges, available cheaply.




With the chromed GL1200 carb covers removed, start the engine and let it warm up to normal temperature. Adjust the idle speed to between 900-1000rpm.



When the engine is warmed up fully, remove the manifold blanking screws. Careful, they may be hot after the warm-up.




Insert the vacuum gauge adapters into the manifolds.




Now attach the hoses from the vacuum gauges onto the adapters, manifold number 2 shown here.


Start the Goldwing engine. Some or all of the gauge needles will fluctuate. Gently adjust the dampers to steady the needles. When they are all steady, you will see how much out of synch the carburettors are.



I usually synch the carbs on the left side of the GL1200 Goldwing first, but you can start on either side. The two gauges on the left are connected to the two left carbs and are now being adjusted in synch with one another. It may not always be possible to get them 100%, but as close as you can get will be good enough. The idea is to get the needles to line up at whatever part of the scale they will, while giving a stable idle. If you try to get both needles into another part of the scale just because it looks better, you may end up with a stuttering engine and have to start again. When you have them as close as possible, give the engine a sharp rev up to about 2000-3000rpm and then close it. Do this a couple of times and check if the gauge needles for each carb keep a common position. If they are way off, you may have a problem with the carburettors that will need to be checked.



With the left side carburettors on the GL1200 synched, we can adjust the right side. Same procedure as before until you get them as close as possible.



As you work, keep an eye on the engines idle speed, and adjust it to 900-1000rpm if needed. If the radiator fan kicks in, it may affect the idle speed. Wait for the fan to stop before continuing with the carb balancing. Some Goldwing mechanics keep a large electric fan blowing cool air to the engine and radiator, to keep the fan from kicking in. When you are happy that you have the carbs as close as you can get them, give the engine a sharp rev up to about 2000-3000rpm and then close it. Do this a couple of times and check if the gauge needles for each carb keep a common position.



Now the two carburettors on the left of the Goldwing need to be brought into synch with the two on the right. The adjuster screw for this is on carburettor number 3. Slowly adjust as before, keeping an eye on the idle speed as usual.



When you are finished, again rev the engine up a couple of times to check that all the gauges hold the same readings. This one worked out well.






If the Youtube video above  isn't working, you can download the clip directly;

GL1200 carburettor balancing video tutorial (MP4 format). 5 minutes, 27 seconds playing time. 34.5 megabytes file size.