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Message: [QUOTE="Vytas, post: 293820, member: 25479"] Whyz, The displacement on the CR80 right now is at 83cc. With the allowable 0.080" overbore the displacement will now be 90cc. This configuration can still be run in the 80cc class. If you go with the Big Bore kit then the bike would have to be raced in the modified class, 80-100?. I do not remember off hand the exact class. Volume(cc) = ((Bore(mm)*0.5)^2*pi*Stroke(mm))/1000 So in stock configuration the CR80 has a bore and stroke of 47x47.8 using these number in the above equation yields a displacment of 82.9cc. By adding 2.03mm(0.080") to the bore you can deterimne the new displacement. [/QUOTE]