i tried yesterday, and it seems not fit.
still dont know where it belong.....
here is the rear brake pic, it does not fit:
Good catch - and further investigation shows Suzuki has a different P/N for the caliper bleeder cap (59122-46H00) and the front master cylinder bleeder cap (59122-01A00). I don't see a bleeder cap for the rear master cylinder in the parts fische.You're right about the size - the inside opening seems to be about 5/16" diameter (worse on the metrics than I thought, ha). The shape is still not like the pic on the yellow caliper or the one you found - more short and squared off than slightly conical.