From: emory!chaos.lrk.ar.us!dave.williams (Dave Williams)
X-Source: The Hotrod Mailing list
Date: Feb 1993
Subject: shortening rods
While perusing a 1977 issue of Cycle Magazine, I found something rather
interesting - an article on Powroll's 541 stroker kit for the Yamaha
TT500 single. The TT500 used a built-up crank, so Powroll merely bored
the crankpin holes further out, sleeved them back to the right diameter,
and pressed it back together. Since this popped the piston out the top,
they were faced with either a custom high-pin piston or a custom short
rod. Since torque was the word, they went to a shorter rod.
They shortened the stock rod.
There is a photo of a shortened rod, with discoloration and a visibly
thickened area at the center of the beam. The process evidently
involved putting the rod on a fixture, heating it until it got soft, and
(probably) using something like a portable hydraulic ram to shorten the
rod. The article mentioned no laboratory testing had been done, but
Powroll had sold several thousand rods over a two year period with no
Nowadays we'd see about mixing and matching rods out of something else,
perhaps narrowing or bushing one end or the other if required, but the
Powroll method is quite interesting. Maybe someday I'll have to use it
[They were doing that trick in the early 70s. We used to use their 125 cc
bore/stroker kit for the Honda 70 minibike. I always marveled that they
could just inductively heat the rod and squish it up and have it work.