David TW125

Hello everyone, I have an issue. A bike issue. I've got a Yamaha TW 125 great engine 11k, healthy. I needed a replacement harness, and last year when I got a used one turns out its, for the 200cc TW. Connecting it up, when the key is on the starter button makes the starter relay click, but when the key is off that relay now turns the engine over, but no spark. Its like, the ignition is backwards. Any help greatful thx