When you changed out your motor did you set your battery on the garge floor?Concrete will drain a battery and when you leave them without a charge for a long time they get sulfated.Have you gotten your battery checked out?If not run down to a parts store or shop and thell usually do it for free.If thats not the case then check the resistance of your battery ground,motor ground, and positive cable to your relay and your starter.If any of them has a higher ohm then 0.1 perf foot then its probably bad.get your battery checked and check your cables and be sure your motor ground is hooked up.