I filled up the tank, to about half full. All the acceleration came back for the whole day till the end of the day, the acceleration died out again.

Seems the lower the gas, the more i'll lose acceleration.. or something of the sort. I haven't a clue. I'll try and check the spark plug, not easy to access

 

Take the plastic off the front and check the vent tube off the top of the tank to the steering stem, sounds like gas tank vent tube is plugged, loosen the cap next time and see if it runs .

 

i have a similar problem anyone have any ideas except even with full tank now the bike wont go faster than 15-25 mph