Here are some possible (and impossible) configurations for the  FZR 400. 


Engine  Bore x Stroke
---------------------
FZR400: 56.0 x 40.5 mm
FZR600: 59.0 x 54.8 mm
YZF600: 62.0 x 49.6 mm
ZX6R:   66.0 x 43.8 mm
TT600:  68.0 x 41.3 mm

 
Stroke    Bore        cc's
---------------------------
FZR4     FZR4+1mm   413.38
FZR4     FZR4+2mm   428.02
FZR4     FZR6       442.9
FZR4     FZR6+1mm   458.05
FZR4     FZR6+1.5mm 465.71
FZR4     FZR6+2mm   473.44
FZR4     YZF6       489.09
FZR4     YZF6+1mm   504.99
FZR4     ZX6R*      554.23
 
FZR6     FZR4       539.89
FZR6     FZR4+1mm   559.35
FZR6     FZR4+2mm   579.14
FZR6     FZR6+1mm   619.77
FZR6     FZR6+1.5mm 630.15
FZR6     FZR6+2mm   640.60
FZR6     YZF6       661.78
FZR6     ZX6R*      749.92
FZR6     TT600*     796.07
 
YZF6     FZR4       488.86
YZF6     FZR4+1mm   506.27
YZF6     FZR4+2mm   524.19
YZF6     FZR6       542.42
YZF6     FZR6+1mm   560.96
YZF6     FZR6+1.5mm 570.35
YZF6     FZR6+2mm   579.82

 (* don't think this config. would work - just browsing)