You shouldn't have any probs but that wire is probably old which means the copper will be starting to oxidise slightly. THis means it will change colour and the resistance of your connection will increase.
Generally not an issue but if you have say 2A going through 0.5 ohms you have 1V across it. If the joint goes bad due to old age copper and oxidising then it might increase to say 3 ohms. THis will give you 6V exaggerated but you get the picture.

I would buy some new wire with a new crimp lug and you will avoid a potentially annoying fault. The beast would likely run with the old wire, but if you're not getting full volts on the coil then your spark will be weaker with reduced performance.