It could be your voltage regulator. Do you have a volt meter? If not go to Wal-Mart and pick up a cheap digital one for about $15. With your quad running it put the leads on each battery post it should be putting out around 14 volts give or take a little. Mine was putting out to much power and I was boiling my batteries dry.
92 warrior, Wiseco +.040, ALBA pipe, K&N, 36MM round slide carb,Ti valve springs, Maier plastic, 14 tooth sprocket, Bandits, Douglas .190's, Fly alum. bars, DG bumpers and nerf bars,oil cooler by Mascman
04 KFX 400