Half throttle or a certain rpm? This one often seems to escape people, but it'd be far more likely to make a rattle at the same rpm all the time since it'd happen at the same harmonic, if that makes sense. For instance, my friends last motorbike would always get a buzzy little vibration at about 11,000 rpm that'd make the girls happy
![Gap :gap:](https://board.marlincrawler.com/Smileys/marlin/gap.gif)