S&S Cycle Combustion Chamber Modification Instructions (Late Chamber) - Manual (Page 3)

NOTE: This modification is necessary to reduce the compression
ratio when increasing the displacement to avoid detonation and
potential destruction of the pistons. An increase of about 3.5ccs
to the combustion chamber volume making a total of 54.5ccs
can be expected. This change coupled with S&S
® special dished
dome #92-2440 series pistons and Harley-Davidson ® head
gaskets, H-D ® #16770-84B, which are .065” thick result in a
compression ratio of about 9.4 to 1.
*All reference to Harley-Davidson ® part numbers is for
identification purposes only. We in no way are implying that any
of S&S
® Cycle’s products are original equipment parts or that
they are equivalent to the corresponding Harley-Davidson ® part
number shown.
3
Place this side of template up for either head.