All Harley cylinders can be machined to accept oversize pistons in order to give them a new lease of life when they eventually wear out. Some cylinders, such as 883 Sportster and the stock bore Twin Cam can also be machined substantially larger to give a useful capacity increase and resultant performance gain.
The popular 883-1200 Sportster conversions are done this way, as are Twin Cam 88-95 and Twin cam 96-103 upgrades. In fact, it is now proven that the Twin Cam 88 can be bored out to 98" and the Twin Cam 96 to 107", all using the stock cylinders as start point. We have pistons available for all applications.
These upgrades are more economical than fitting new cylinders and also offer three distinct engineering advantages. Firstly, even a lightly used cylinder will have undergone a number of heat cycles, which makes it more stable and much less likely to distort in use. Secondly, our Harley specific boring and honing techniques, coupled with our own designed and manufactured torque plates and Auto Stroking Powerhone machine, holds bore size and geometry to plus or minus one tenth of a thousandth of an inch (.0001"). Thirdly, we impart the correct cross hatch pattern and plateaued surface finish onto the cylinder wall which gives very fast piston ring seal, minimum oil consumption and a long service life.
It is also an unfortunate fact that many new cylinders, out of the box, are badly sized, particularly with regard to out of roundness and taper. By prior arrangement and subject to work load, we can normally offer a same day turnaround on this service. Please note that we do not bore and hone cylinders to suit pistons purchased elsewhere.
For an in depth description of each of the stages in the boring & honing process including an overview of our highly accurate method of measurement, read our boring & honing technical article.