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Old 01-29-2013, 09:36 AM   #73
greglewis
Adventurer
 
Joined: Sep 2011
Location: Oak Park, Illinoisistan - the straight road state
Oddometer: 66
Quote:
Originally Posted by ktmmitch View Post
Our initial donor engine is an 08 motor,so 654cc.This is 102mm bore x 80mm stroke.
Our initial attempt is to keep the std bore,and gudgeon(wrist) pin height,then move the crankpin 12,5mm nearer to centre of crank,giving the 25mm reduction in stroke needed to achieve 102 x 55= 450cc
But,because of the reduction of swept volume,we have to "lose"approximately 20cc from the head volume to maintain the same compression.That will be the difficult bit,as we will be running the rally cam,so there will have to be quite a pronounced dome on the piston to up the compression,but still miss the valves.

Onward & upwards..........
Thanks - I couldn't ask for a more informed response. Please keep posting the progress of the build, and the best of luck!

Greg
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