You should be able to, especially with the LED lights, as LED lights draw less current then a typical incandescent bulb (as in, your typical OEM lights).... so you'll actually have more amps left over potentially to power such things as a motorcycle jacket per se'. However, since the LED lights draw less current then the typical bulbs, you may notice the flash rate of your turn signals will noticeably quicken. This can be solved in many ways, as there are lots of etailers that make LED specific turn signal relays that will solve this. There are many other ways to deal with this, but I seriously wont get into those as I'll be here for a while, and a lot of it would be over most peoples heads.
Its not the battery capacity to really have to worry about, its the amperage the alternator puts out. If the current draw of your heated jacket exceeds the amount of amps your alternator can put out, the power will have to come from somewhere, which will then be drawn from you battery.
Obviously you don't want that to happen. Not only will the excess current draw cause your alt to overheat, but the added requirement for amps to heat your jacket will fully discharge your battery, so when you shut the bike off, you wont be able to restart it without boosting it. If this happens, you'll likely kill the battery if this happens more then a few times. Each time a battery is discharged until its dead, it loses about 20% its capacity.
I don't know how many watts your jacket will consume as you never said which make it is, or style (etc), but I searched online, and I assume it'll need between 90 to 110 watts.
Now using a calculator such as this... http://www.the12volt.com/ohm/ohmslawcalculators.asp#current
^ at 110 watts, it'll draw a total of 8.46 amps for the typical 13 volts of current. This should be fine, but I wouldn't recommend putting any additional load on the alt, as in a more powerful headlight or the like. EDIT: do the same thing with your gloves as well.
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