Depending on the brand of the battery - they are sometimes not strong enough to supply the cca (cold cranking amps) required for starting a motorbike. Certainly the larger AH rated batteries will work, but it seems you are after something that you can mount in any direction.... if it's a ups it may not be up to your task... look at the battery specs closely.
To get away from the lousy little connectors on these batteries - solder/heatshrink some decent cable on them and on the cable ends put your normal nut/bolt connection - with appropriate spark protection (larger heatshrink)..