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Discussion Starter · #1 ·
Hi everybody,

My first post! Before I get into a much longer post about my new(old) motorcycle and its issues, a quick question that hopefully someone with 450 carb experience should be able to answer. I bought her with some Keihin CB450 carbs on. The left one is a 723a with 145 main jet, the right one is a 723b with 150 main jet. I've taken them apart to look over, and I noticed a huge difference in the springs in the vacuum piston on top.

This may sound stupid, but are those even supposed to be there? The schematics on both bikebandit and the Clymer manual show no springs in the top of those 450 carbs. I know the 723a and 723b are slightly different, but its a HUGE difference between these two springs. The 723b(right side) spring measures 3/4in diameter by 3.5in long and is gold, while the 723a measures 7/8in by 2.5in and is a greyish color. The amount of pressure the 723a spring takes to move the cylinder and needle up is about 5 times what the right one does. If they are supposed to be there, does anyone know if these are the correct sizes? Any help is much appreciated. Thanks!
 

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Sensei
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There are NO springs in any 5-speed 450 carb....... There was an attempt to cure the early carbs (4-speed) with a kit that had springs, but it didn't work very well......
 

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Discussion Starter · #3 ·
Thanks 66Sprint! I figured those didn't belong in there. No clue how they got there.

Next question then, would having said springs in there possibily limit my otherwise great running bike to about 50mph??
 

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There is the possibility that someone had some early Goldwing carb experience and used the springs from the GL1000 carbs.

The carb caps will swap between the GL1000's and the 450's (I've done it) and I think the slide will as well although I haven't investigated that yet.
 

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Sensei
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Yes.... Take the springs out and try it!.....
 
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