would a monogram speedy look ok with a black motorcyle jacket?

Yes but be careful of rub off! I wore a black bomber jacket with my NF and it got black marks on the vachetta (part of the reason I sold it). My jacket wasn't even leather but it was black and it rubbed off. If you put the handles over your jacket just be aware that this could happen. If your bag has a nice patina it might not be a problem. My bag was brand new when I wore it with a black jacket.
 
your bag is an accessory.. it should stand out... YES WEAR IT! I have used mine while wearing a black winter coat and black leather jacket....

its a neutral and goes with EVERYTHING!
 
Yes absolutely, like bag fetish said, it's an accessory. I have a balenciaga leather moto jacket that I wear with speedies and all bags that I have. Don't over think it!
 
The print works with black motorcycle jacket...but I'd be selective with the style. Speedy 30 is ok, for instance, but I'd not wear a Tivoli PM which looks dressier/more feminine.