This part is not about alarms, but it is related to the topic, tangentially...If you tour on your bike, an easy way to discourage looky-lou's at your motel/hotel, is to put a cover over your bike. It will keep people from looking it over, and it will keep the seat dry, should it rain. An alarm, as discussed by Mark, is even better, but combining the two, is probably the best option.
Now for something directly related to your posting...Regarding electrical loading of an alarm system, look up the specifications on its current draw. It likely is quite low. The standard battery for a CB750 is 14 Amp-hours, which means it will supply 1 Amp of current, for up to 14 hours, or 1/10 of an Amp (100 mA), for up to 140 hours, 1/100 Amp (10 mA) for up to 1400 hours, etc., before it is drained. As long as you do not leave the alarm activated for several days, continuously, it should not harm your battery,
if the alarm system has a low current draw (see examples above, for current draw, and time). Cheers!
1979 CB750K (sold, 2012, but not forgotten)
1983 Kawasaki 440 LTD Belt Drive (sold, 2011)
1993 Kawasaki Voyager XII