Honda Vision 1986, Tuning help
 

I have just purchased myself a 1986 Honda Vision 50cc, Its fully stock and only does 31MPH i was wondering if there are any big bore kits like 70s, 80cc etc, I have done some research and found the honda spree 50 is also got the same enigne, Anybody know what big bore kits would fit or where i could buy one :Dplz, Thanks in advance