BS38 Needle Plates coming loose

Anybody have the problem with Needle Plates coming loose on carbs? The needle plates are the plastic button shaped dohickey that keeps jet needle in position, inside the slide and diaphragm, under spring. When I bought this '76 kz750, one of the carbs had the plate halfway up the slide. Last week (2 years after buying bike) the other one had come loose enough that needle came out of jet and rested beside jet. Looking for someone to commiserate with me and possibly suggest some sort of prevention. Thanks!
MTG

Do you have the correct needles in them? this is what Kawasaki shows: 16009-070 Jet Needle, 4JN19
The plastic washer should stay put by spring pressure, this is its only retainer besides the adjustment clip. The only way I can see it pushing up like you say is to have shorter needles, lifting out of the jet. Then as the slide comes back down it pushes the needle up into the slide.

That makes sense but I have no way of knowing. I am assuming I got the correct rebuild kit since everything else worked. It may be a coincidence that the first carb was before rebuild and had same problem.

muddytailgate wrote: Anybody have the problem with Needle Plates coming loose on carbs? The needle plates are the plastic button shaped dohickey that keeps jet needle in position, inside the slide and diaphragm, under spring. When I bought this '76 kz750, one of the carbs had the plate halfway up the slide. Last week (2 years after buying bike) the other one had come loose enough that needle came out of jet and rested beside jet. Looking for someone to commiserate with me and possibly suggest some sort of prevention. Thanks!
MTG

The BS-38 used two different types: the ones in mine use the metal clip which holds the plastic button from sliding down so it can't do that.

The other type (shown in the picture) might, I have not worked with those.

It's possible they may be assembled wrong or have the clip in the wrong slot? As said above. the spring should hold the plastic washer in place against the clip that snaps into the needle slot.

Is the clip tight in the slot?

NOTE: the needle should not be moving up and down with respect to the slide body in operation, the spring should hold it all the way up. The "floating" needle assembly with spring is so the needle can move around and match the position of the jet as the float rises and falls. Needle should not be moving around in the slide.

huh, funny. As i recall: needle clip on needle, needle into slide, plastic button over needle, spring over button. Maybe when I rebuilt them, I didnt press button down all the way. i noticed last night there seemed to be a false bottom at first, but I am really grasping. I was sure I would get a bunch of "oh, yeah, happens all the time" replies. Thanks guys.