HB 125 Install
 

Hydraulic primary chain tensioner

http://www.hdforums.com/upfiles/2318...24569FE25B.jpg

Here's a link to the installation of the HB 125 primary chain tensioner, the difference between this and other tensioners is that the HB 125 has a hydraulic piston that dampens chain movement that uses primary oil to do it.

http://www.sohotbikes.com/downloads/instructions.pdf

The best price I found to date is .... HERE