Need help with moped cylinder!!?

hi, i have a betli xr2 moped, its a 49cc 2stroke single cylinder air cooled, motor and its about 1 year old, lately i have been trimming it to extreme levels, after i switched the powerbox i made it go around 70MPH's, so about 2 days after switching the powerbox i was driving on the highway, and it just turns off, i take it to the shop, and it turns out the 49cc cylinder broke, so a 49cc engine is too small to handle those high RPM's, if i bought a 70cc do you think that is stronge enough to handle doing 70MPH?