I just got one for $150 that seems to be in similar shape to yours. mine also doesn´t fire without the battery, but i´m not sure if that´s normal or not for this bike. it runs great with a charged battery. you might try that first, that would also help me know if i´m looking at a bad magneto or something, or just a limitation of the bike (although both bikes might have the same busted part, i guess).