Hi Joel, what generator aren you using ? Several years ago I installed a sealed lead acid battery on a friends chief. On a long test ride the battery failed, and pulling over to the side of the road, I discovered the battery had blown up like a balloon, an the case was starting to crack.
Turns out that generators with the original style mechanical voltage control will not stop overcharging completely, and the system will effectively control excess charging by boiling the battery a little. This is why so many battery boxes, trays and chaingurds on antique bikes are rotted with battery acid. A seled lead acid battery has nowhere to vent, so will distort and fail thru internal pressure from the acid producing gas. In the case of my friends chief, which was fitted with an original autolite , I suspect it was minutes away from exploding.
The easy cure if this is the case is to fit a solid state voltage regulater. Gene Harper makes one such item that will fit inside the cap of a DU7.
Adjustments can be made to lower the voltage of a three brush generator too, and using full running lights will help with a Splitdorf, the charging system only supplies lights and horn, so a fully working genny will boil a battery if lights are not used or the bike is run with led lighting.
Antonio esteves makes a repro DU7 generator that comes with the solid state regulator. I do not recommend any of the alternator models designed to look like a Splitdorf, in my opinion they have too stron a pu on them for the generator drive mechanism.
Let us know how you go with your investigations.
Tim