has spark and fuel, wont start.

a friend has been helping me doing research, and found a 10 page post somewhere that explains how to convert. he was telling me i NEED the 4 pin resistor. whats weird is that i worked just fine with the 2 pin resistor for a good while. and just stopped working after sitting for a few hours. anyways, if this is the case that i need the 4 pin resistor, should the box still be okay? i mean i get spark out of the plug, just seems very weak? would this make sense to do so?