Carbeurtor Butterfly shaft mods


XS400 Enthusiast
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Toronto Ontario
Hey there ,

I’m going back and working on these carbs. They’re for a 650 but I have the brackets for the 400. Only issue is the shafts need to move about 6 -8mm . I think I’ve got 3 options to get these to work.

1. cut away these red areas . Only issue is the piece may not be strong enough and will snap . This also might not be able to give me enough room.

2. Drill and tap new holes where the dots are and cut away the rest in red . There’s an “elbow where the tapped one would be so I’m worried that would cause issues . Not to mention how fine the threads are.

3. Cut the shaft and washer and then reattached the “L” piece . I’m worried this will be the hardest. Does anyone know how these are attached ? Brazed ? Or peened?
It may be easier to adapt at the other end of the cable and leave that alone. Use 650 cable and maybe even hand throttle assembly.
The linkage end plate is peened on, the dent in the center of it does it. Grind the protrusion to dead flat and the plate will peel off the shaft, it can be heli-arced carefully back on. With the shaft removed from carb of course. I've re-peened them before as well.

You will likely not find the screw thread tap for those super fine threads, commonly they are machine tool supply available only as the public never uses them and they cost megabucks since they are unobtanium.
I’d go with No1. Looks plenty strong enough. No 3 means cutting the carb body, hmm, and No 2 looks too close to the fold to tap.