here you go from some of the discussion.
[quoted from biggiecamp]
[By that theory it would be a 27.4 with +2mm stroker crank instead of 27.2
The displacement isn't alway a direct addition. There's a formula for it. One of these guys probably knows it.
34mm jug (stock 26 cc) with....
stock crank =25.4
+1 crank = 26.3
+2 crank = 27.2
36mm jug with.....
Stock = 28.5
+1= 29.5
+2= 30.5]