Stuart,
I wouldn't mind sticking with the 6 volt system, but that 6 volt battery can barely turn the engine. It's rated 625 cold crank --- greater than the 12 volt! I wonder if it's a bad battery? I charged it up completely. The 12 volt gets drained after 6 or 7 cranks of 10 seconds each. That seems a large power draw, doesn't it? Maybe the engine is so tight it's hard for the batteries to turn it. It did start though.
