38 tooth Primary gearing change
 

 
As mentioned, a common gearing change for the U.S. and international XR1200s with the 34-57 tooth primary gearing, is to change to the alternate 38 tooth primary gear  that is used on the Brazilian and Japanese models.  The parts are optional XR1200 parts from the HD parts manual  (HD part number 30029-08 with 96-link primary chain 40147-04), and are easily purchased in the U.SWith this change, the speedometer remains accurately calibrated.
 

Although not for everyone, this is a nice change for an XR with engine improvements that has more power and can pull the gearing, or for XR tourists who want to drop their rpm at highway cruise speeds.

 

The below shows calculations for this gearing...

 

XR120038572868w180GearingChart3000rpm.jpg
38-57-28-68 at 3000 rpm

 
 
As can be seen in the following chart, with the 38 tooth primary gear installed, the top speed of the XR1200 increases by about 15 mph at 6,800 rpm over a XR1200 with the 34 tooth primary gear.
 

XR120038572868w180GearingChart6800rpm.jpg
38-57-28-68 with 180 tire at 6800 rpm

 
 

Enter supporting content here