- Thread starter I AM B17
- Start date

66 * 66 * 3.1415 = 13684.374.....add 900mm*2 = 14584.374..... divide by 3.1415 = 4642.487, take the square root = 68.136mm

68.136mm is the max allowed bore, Stock bore is 66mm.

http://www.mk5cortinaestate.co.uk/calculator2.php

Dont mean to nit pick Ted, but 68mm bore will yield a 261cc capacity. Also most 250's after 2001 are 66.4 stock bore and 72 stroke.

66 * 66 * 3.1415 = 13684.374.....add 900mm*2 = 14584.374..... divide by 3.1415 = 4642.487, take the square root = 68.136mm

68.136mm is the max allowed bore, Stock bore is 66mm.

Actually Tim, thats a really good point to argue. I hope you also argue the case of 450mx competing with the 250mx 2 strokes in AMA. Also that the 125's couldnt even get a look in until they allowed the 144cc conversion.

http://www.mk5cortinaestate.co.uk/calculator2.php