Engine sounds like a sewing machine on start-up

Doesn't happen all the time but just to get the old adrenaline running my lovely little Mazda Eunos likes to sound like a hyperactive sewing machine. The sound stops pretty fast but I was wondering if anyone else has had the same problem or could figure out what's happening.

does the RPM revv higher?

At the moment it being a typical freezing cold British winter the RPMs are always higher until the engine warms up, in fact, come to think of it, I never heard that particular sound during the brief summer. What do you think?

hmm i don't know what it is...??

try minor stuff like a tune up..