Motorcycle Repair: 1977 Yamaha XT500 Carb & Battery, spark plug fouling, yamaha xt500

Question
Hello again Chris,  I have a 1977 Yamaha XT500 enduro.  Problem 1 the 6 volt battery on this bike is bad.  Does the bike need a working battery to run since the bike is a kick start?  Is this battery used for more than powering the headlight/tail light & turn signals?  Problem 2 I seem to be fouling out spark plugs and there is gas occasionaly pouring out of the overflow tube.  Is the spark plug fouling related at all to the carb overflowing?  What should I do to resolve these problems?  
Once again, I thank you in advance for your time & advice.  If you have any helpful info that would help me keep this fun bike on the road I would greatly appreciate it!
Thanks again,
Shawn

Answer
Hi Shawn.
 The battery may or may not be needed.  It depends completely on how the electrical system on that bike is set up, but my guess is that it does require the battery as part of both the charging system as well as the rest of the electrical system.

 As far as the plugs fouling and the overflow, that sounds like the carbs have sticking floats.  This is a bad thing.  You may want to pull and do a superficial cleaning of the carbs.  Do not pull the needle valves.  Check the floats for proper function as well.

Start there and see what you find.
Good luck.
FALCON