Originally Posted by KASUYAHO
It will be interesting to see what way they decide to go with the engine to get 450cc seeing there keeping to same size bore.
Great to see guys / girls thinking outside of the box
Good luck Jenny
102x84.5 is 690 specs
so 102 bore with 55 mm stroke is 450 cc
so they will lengthen the rod and drop the wrist pin to make up 30 mm in stroke. It sounds like they are doing mostly rod lengthening because they are going to use the same basic piston as a hi comp 690 piston (close to stock wrist pin location therefore)
This should keep the scrutineers scratching their scalps