New to the bike world, just bought myself a new 22 RC390. Been riding it around gently to break in the engine, and keep noticing that lower RPM (around 4k) in 4th gear will have a scraping or sliding sound. Almost like plastic/metal on metal. Is this because the gear is straight cut and therefore just noisier? Pretty annoying because 4th gear 4k rpm is a really comfortable spot for cruising in town but the scraping noise is pretty noticeable. Any ideas on what it could be?