Other design features intended to reduce noise include an offset piston pin
position and the incorporation of a steel strut into the piston - both of which target reduced piston slap - along with improvements in engine gearing.
The two-piece design consists of a forged steel crown and cast aluminum skirt with a large diameter floating piston pin
and with a rectangular intermediate piston ring and a keystone top ring.
To lessen piston-generated noise, the piston pin
is offset and the Art single-piece aluminum piston incorporates a specific profile designed to accommodate thermal deformation of the cylinder and reduce piston slap.
To allow removal from above, the reentrant piston is attached to the piston pin
by an axial set screw countersunk into the center of the piston crown, within the re-entrant "pip." According to Hatz, this positioning does not interfere with the piston's re-entrant gas flow effect.
"With the Monotherm design, there is less material between the top of the piston and the piston pin
. The shorter pin reduces weight and gets the piston on par weight-wise with an aluminum design.
To maintain reliability with the higher output, internal components have been strengthened with a stronger piston pin
, larger connecting rod, larger rod journal and redesigned oil control ring.
A connecting rod is inserted into the piston pin
bore, a pin is inserted to attach the connecting rod to the piston, the piston rings are added, and the entire subassembly is oiled.