Replaced all essential parts in 1990 Keihin CV carb, but didn't solve the overflow. With float bowl off, the float (checked for leaks), the new float valve shuts the supply correctly; float level set according to manual at 18mm, later raised to 20mm. The float chamber drain seals well. Mounting the float bowl again causes overflow. Using transparent overflow tube, it appears that the level reaches the tip of the overflow tube, causing the overflow. Can't find the cause for the float needle not shutting off supply with chamber installed, unless float is restricted in movement with chamber on, but doesn't look that way. Any suggestions other than the usual? (new needle valve on clean seat, new gaskets, o-rings, accelerator pump diaphram, etc.) Any way of checking float movement with chamber installed?