MIDI is a standardized set of messages that enables MIDI equipped devices to communicate
with each other. It was first introduced in 1983. It's bread and butter use is to tell a
sound generating device to play particular note/s and when. It can also communicate
utilitarian messages and the one I think that you probably need is MIDI clock - which
synchronizes the tempo of a device with the MIDI clock sender.
You need something
that generates MIDI clock. I haven't tried this but this looks like it might fit the bill
(you have a computer and the cheapest MIDI clock is a free one):
need a MIDI interface - you get get cheap USB ones like for instance:
and connect the MIDI out cable on that (or whatever else) to your Mopho
MIDI in socket.
I can't guarantee that will work the way you want it to but it's the
right kind of idea, if MIDI indeed can sort your issue out.
With a DAW you
can record MIDI information from your keyboard and send 'recorded' or sequenced MIDI to
your keyboard to tell it what to play.