Wolf Islander 50cc issue

[Two Wheeled Varmint]

Hi.
Wolf Islander w 3500 Miles.
Initial problem was very jerky acceleration above 35 mph.
Changed variator (old rollers were shot) with set that included 6.5 gm rollers.
Jerky acceleration stopped, but now bike is struggling to get above 35 mph on flat road......when functioning properly I'd easily hit 40+.
Do I need heavier (8gm) rollers??
Please Help!!