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Having had the benefit of being able to think about this without a hangover (!) it's boot out of gob time! I would, therefore, like to apologise...shortening the rod will indeed increase the cylinder capacity but the CR (compression ratio) will also fall so the power increase (if any) might not be what you would expect...increasing the swept volume is really the way to go but of course you then have to use spacers etc. to ensure the piston at TDC clears the head and to maintain the correct CR.

Regards

Jan



Umm, yes and no. Shortened rods will increase the swept volume, which is the volume disolaaced by tthe movement of the piston plus the extra volume above the piston at TDC. In otherwords, it increases the compression area by extending the combustion chamber down into the cylinder. A 780CC engine would still displace 780CC, but the compression ratio would be reduced. An undersirable side effect of shorter rods is a les favourable stroke:rodlength ratio. The longer the rod is relative to the length of the stroke, the less engine torque will be diverted to trying to push the piston sideways through the cylinder wall.
If one were to find it possible to increase the stroke of his bike engine, it is better to try to find pistons with the wristpin (gudgeon) holes higher or to get a stroker plate made and fit it between the crankcase and cylinders.

Let's hope there's intelligent life somewhere in space 'cause it's buggar all down here. -- Monte Python