what is the difference between the stage 2 103 pistons vs the stock 103 pistons? are the stock 103 pistons dished or are they already flat tops? just curious for reference in they dyno numbers. thanks for the info.

 

2012 HD Screamin' Eagle Parts catalog, Page 13;

http://www.harley-davidson.com/en_US..._SE12_Full.pdf

B. Screamin’ Eagle Big Bore Stage II Kit
for efi Models – 103 cubic inches*
the Stage II Big Bore Kit provides the parts you need to
increase the horsepower of your eFI-equipped model. the
kit increases the displacement of your twin Cam-equipped
model from 96 cubic inches (1584cc) to 103 cubic inches
(1690cc). Includes Stage II (Se-255) cams, Big Bore cylinders,
Big Bore flat top pistons, rings, pins, clips, and a Stage
I Air Cleaner Kit with one-piece back plate, integral breathers,
all mounting hardware, and gaskets.

The difference in dyno numbers would be the installation of the SE255 cams versus the stock cams in a 103.

 

i get that the stage 2 pistons are flat tops for the 96 kit. but are the factory 103's already flat top pistons? so the compression for the 96 stage 2 vs. the factory 103 should be the same unless thin head gaskets are used? i'm guessing.

 

Yes.

No. Like I said before, the increase in corrected compression is dictated by the cams used. In this case the stock intake valve on both a 96" and 103" factory cams close at 30* After Bottom Dead Center, or ABDC, for a corrected compression of 9.42:1.
Installing the SE255's, which have an intake valve close of 25*, in a stage II 96" engine, and the corrected compression goes to 9.55:1. This is with the stock head gasket thickness.
If you were looking for even more compression, then you start exploring milling the heads and thinner head gaskets.