GL1000 Carb Mystery Parts

[cfairweather]

I am working on some old GL1000 carbs and had to make some parts. Can you tell me what I am going to do with these things and why?

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[cfairweather]

These these are to plug the shaft ends on carbs #1 and #2. I ran into a couple of carbs that were missing the blank washer plug that Honda used to cover the choke shaft end and one was missing the brass cap. I decided to make these out of TPU.

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In the process, I learned some things that might surprise you. Did you know that Honda only used one casting design for the 4 carbs? Yes, I have concluded the same casting was slightly modified to make unique #1, #2, #3 and #4 carbs. I have concluded they took the generic carb body and made these changes:

#1: They drilled a hole for the vacuum line that goes to the air cut valve. They installed the brass cap and blank washer on one side to cover the shafts. This is the side with the brass elbow.

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#2: They installed the brass cap and blank washer on one side to cover the shafts. This is the side without the brass elbow.
#3: A groove was added to the linkage side to allow for a wire clip to attach the choke linkage. This is on the side without the brass elbow.
#4: A groove was added to the linkage side to allow for a wire clip to attach the choke linkage. This is on the side with the brass elbow.

There is probably a groove under the brass caps on #1 and #2. Honda must have saved a lot of money by designing the carbs and heads like this. They made one design and made them able to function in different ways with minor modifications. Some very smart people made this motorcycle and I am very impressed with how they did it all.

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[pidjones]

They have evolved a bit from the original automotive carbs:

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[Old Fogey]

There's no groove under the brass cap on #1 and #2

[redglbx]

PID, Are those carbs in your photo from an automotive application? They sure look different than the oe’s. Maybe all accelerator-pump bowl castings ?

[Old Fogey]

I think those are pictures of the original prototype carbs on Wing #2 that Pistol Pete restored.

[cfairweather]

John and PID- As I look at those carbs again, I now understand why some of the early carbs have an unused hole. I am doing a set of 755A carbs right now and a couple of the carbs have a vacuum hole that would support the individual cut valves. This hole is covered by the edge of the GL1000 float bowl, so it doesn't have any real use today. Here is the hole:

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[Old Fogey]

I've noticed that hole before on a few carbs, but never knew what it was for. Now we know: Accelerator pump for the the Civic carbs.