Bike bogs down (not engine) and noisy only when moving

[gaz73]

Ive just spent a lot of money on my Italjet Formula 50 LC scooter but ive always had a problem ive ignored as it comes and goes and I usually just pull over and wait for the problem to go away after a few minutes.

What happens is it bogs down (not the engine) as if there is about 30% brake being applied and at full throttle im getting 30 mph and i cant get up hills. I suspected the rear brake pads but the problem happens even when I dont use the rear brake at all or if I remove the pads, when i coast to a stop it feels just like a brake is slowing me down.

Next problem that could be related is there is a strange scraping noise coming from the transmission when im moving along, theres no noise when im stationary, its most noticeable when coasting to stop with no throttle and the sound is very similar to those old and loud coffee peculators.

Would anyone know what the heck this is? had this for the past 11 months now ever since I got it.