What's the biggest bolt on bore up kit for a 50cc engine?

[Motocrf50]

how big can you go before you have to bore cases etc?

[Ste_13]

51.5cc

its a monster

[Ste_13]

im sorry

72cc i think, comfortably anyway

[englishjenny]

i no the honda 50 engines can be bored out to more than that a lad up cowms is now 124cc

[thumpstar 2010]

72cc i'm sure of it.

[Motocrf50]

That's what i was thinking, but AJS offer an 85cc kit for there DD50 which use the same type of engine as pit's so i was thinking a 90cc may be possible. does anyone have a 90cc cylinder which they could measure the base size of to see if it can fit? was also thinking it might be possible because if u look at the Honda cub it comes in 50,70 & 90cc , and if im correct the only difference is the cylinders, heads and pistons?