It is set to 100khz. You can change it with inline C.
B4X:
Sub Process_Globals
Public Serial1 As Serial
Private master As WireMaster
End Sub
Private Sub AppStart
Serial1.Initialize(115200)
Log("AppStart")
master.Initialize
RunNative("SetWireClock", 400000) '400khz
End Sub
#if C
void SetWireClock(B4R::Object* o) {
Wire.setClock (o->toULong());
}
#end if