For what it's worth connecting one battery to your bike backwards will not cause a spark unless something is on/shorted and in that case would have sparked even if connected correctly.
Reversing leads when jump starting is another can of worms but still shouldn't blow fuses.
I think what Dizzy is hoping, is that when you say temporarily, you mean "for test purposes". We better not find you riding around with tin foil fuses!!Connected the contacts with some foil temporarily. It's getting juice so no damage! Whew...
Thanks for the assistance.