problem

hello I'm new to rideing and im haveing a problem with the wheel it will spin freely for 90% the chain will be very lose then it will get very tight and be hard to move idk what this means I was thinking it must be the chain itself any opinions? I'd love to hear them thank you

Hi, I did a track day yesterday on my stock rc 390 2015 and during the third session I started having an issue only in 4th gear accelerating hard above 6.5k rpm, where it feels like the gears are jumping or slipping or something. If I accelerate gently I can go right to the limiter in 4th no...