Originally Posted by
chunk t
Marcus,
The 14mm obviously has a slightly longer stroke. As the stroke lengthens you could (might) see a bit more torque at the low end... but that will also depend on the port timing, deck height, bubble volume and compression ratio the mfg'r chose. In reality a longer stroke engine is a bit more forgiving to tuning, & I bet that was the mfg'rs ultimate goal for the mill your referring to.
chunk
14mm refers to the diameter of the cranks barrel, not its stroke. The reason some motors have gone to a 14mm crank is strength. When a good mod'er starts grinding on a crank inlet it can get pretty thin and some were breaking. The added mass can take a little bottom end punch away, though with really aggressive onroad clutch set-ups it can actually give more snap on the bottom.