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synchronize butterflies without removing carbs
- Thread starter marp68
- Start date
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- Tags
- carburetors
Usually it's done with gauges of some sort if the carbs are mounted. What carbs are you dealing with? Later linked type or early separate carbs with two throttle cables? Sync procedures differ slightly between the two types.
OK, then you don't have any place to attach gauges unless you've installed newer style manifolds with the vacuum nipples. About the best you can do is set the idle speed adjusting screws so that they are an equal number of turns in. Turn each one in until it just touches the cable arm, then give it one full turn in from there. Start the bike and dial the idle speed in to 1200 RPM by adjusting BOTH idle speed screws equally. In other words, turn each screw in/out the same amount so their "turns open" setting remains matched. This is step one.
Now you have to match the amount of freeplay in the cables to one another so both butterfly plates begin to open at the same time and will be open the same amount at any given throttle opening. I do this by setting the left carb freeplay where I want it (about 1/8") and locking it down. I then loosen the right carb's cable even more, so it visibly has more freeplay. I then roll the throttle open slightly, just enough to take up all the freeplay in the left cable but not enough to start lifting the cable arm. While holding the throttle there I adjust all the extra freeplay out of the right cable.
Now you have to match the amount of freeplay in the cables to one another so both butterfly plates begin to open at the same time and will be open the same amount at any given throttle opening. I do this by setting the left carb freeplay where I want it (about 1/8") and locking it down. I then loosen the right carb's cable even more, so it visibly has more freeplay. I then roll the throttle open slightly, just enough to take up all the freeplay in the left cable but not enough to start lifting the cable arm. While holding the throttle there I adjust all the extra freeplay out of the right cable.
The steps for syncing the two cable carbs is in the Clymer book page 20. I do this with both cables unhooked. Once I get the carb adjustments right I then hook the cables up. Then do as step 5 indicates.
Leo
Leo
I know how to sync the throttle cables freeplay already. I do it with the plastic cards method.
But I may have misunderstood the butterfly mechanism. I thought they were connected to each other on a shared rod and prealigned. But they are not, right? That's why there are two throttle cables that need to be synchronized.
The prealigned and connected butterflies refer to the single throttle carbs, right?
Sorry about the question
But I may have misunderstood the butterfly mechanism. I thought they were connected to each other on a shared rod and prealigned. But they are not, right? That's why there are two throttle cables that need to be synchronized.
The prealigned and connected butterflies refer to the single throttle carbs, right?
Sorry about the question
Yes, the connected butterflies are only on the later linked carbs. But even though those later carb butterflies are connected, they're not prealigned. You have to adjust the right side one to match the opening on the left side one using the sync adjusting screw on the linkage.
