I ride a Honda Rebel 250 motorcycle and over the past few days I find that the bike is losing power when accelerating fast.
When I twist the throttle to accelerate quickly (in any gear) I hear the engine sound increasing in pitch by a lot more than I'm used to hearing, but the motorcycle doesn't seem to respond and performance is very poor. If I then twist it back to a position of slow acceleration, the engine noise returns to I'm used to hearing (still the accelerating noise but a lot lower pitch) and the performance also seems to be appropriate to that level of acceleration.
What could be wrong with the motorcycle?