Bore and stroke mean very little to a factory race team.
There are many BxS combos that will fit in under the 450cc limit. Even MX teams play with bore and stroke to move the revs and torque around.
That is what Doug Dubach did for Yamaha in the 90s....years of testing different combos until they had what they tought worked the best.
KTM factory team could take an RFS or SXS or Xc4 motor and change the BxS as easily as most of us could do a valve adjustment...
Anyone have a pic of any of the last Dakar bike motors?
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