[Harrisonweare]

So I bought a 1/4 throttle for my wpb 160 2 win, I tried installing it onto the bike with the cable it came with and when I started the bike it was as if the throttle cable was too short, as soon as the bike started, it would jump up to high revs and then hold it there, so after messaging the guy I bought it from they said a 13cm excess would be needed, so I ordered the cable and now it's as if the cable is too long? The throttle doesn't snap back like it should, please help I'm out of ideas 💡