For ignitions that are the same except one kis a single and the other is a twin, the twin doesn’t need more voltage. Most Chinese ignitions, even the early ones were rated for a range of voltages, usually from 4.8 to 6V. Later ones have significantly broadened that recommended voltage range upward with most of the recent ones not working on 4.8v at all. I’d try at least 6 to 6.6 volts. What do you have to lose? It isn’t working now.