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Balancing carbs

10239 Views 13 Replies 9 Participants Last post by  Abes_CW
I had seen some discussion of carb balancing before the forum moved over here, but I had never found a full "how to" on it. Can someone point me towards one?

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I found lots of info on making my own tuning tool with ATF & clear Hose. Just wasn't sure where I was hooking the hose up to and what I was adjusting.

Here are a few pictures to show you where the vacuum tubes go from the balancer that you choose. The tubes that go into the intake manifolds have M5 X 0.8 mm threads. You could buy a long brass bolt and drill the center of it out after cutting the head off it to connect the vacuum lines to.

As for the restrictors Shep is referring to, they usually go into the tip of the vacuum hoses. Mine have a .025 hole in them to cushion the strong vacuum signal. It smooths it out so you'll be able to get an even reading when the engine is running. If they are not restricted the indicator in the tube will bounce up and down and you won't be able to read it accurately.

As stated above when your balancing the carbs it only takes a tiny amount of movement on the center adjustment screw to make a difference in the balance. When you loosen the lock nut, (just enough to let the center screw move), turning the adjuster counter clockwise will raise the vacuum for the right side carb and the indicator will rise higher in the tube. Turning the adjuster screw clockwise will lower the vacuum for the right carb letting the level go lower in the tube.

Don't be tempted to get a balanced level with the nut loose and then tighten it up. Adjust in very small amounts and then tighten up the lock nut. Then snap the throttle a few time so the connecting linkage between the carbs centers itself before you take the reading. It needs to settle again in it's centered position after you have moved it around with the screw driver and 8mm wrench/tool. As Shep mentioned, you can get small amounts of adjustment by tightening the nut a little more. But it won't do much if the balance is way off. And be careful you don't strip the nut tightening it up too much. It's just holding the screws position, not holding the wheel on the bike. Go firm enough to do the job.

Be patient. It takes a while sometimes to get it correct. It can get frustrating when your doing it for the first time.

Cool, thanks! The pictures help immensely.
A quick tip that worked for me - instead of an auxiliary tank, I placed my regular tank back back where the seat normally goes, and used a 2 foot piece of fuel line to go from the petcock to the carb. Bungee cord the tank down and have at the balancing act.

Good Idea, I think that will be easiest.
What year is your bike?,if it is an 81 or 82 it probably has a vacuum petcock that would also need to be hooked up. Also if it has a vacuum petcock and you use an auxiliary tank, you need to block off the vacuum port to balance the carbs.

Its an '80
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