The 575XR Upgrade
 

 
It always seems like one of the first mods people look for on a Harley is camshafts.  The XR is no exception.  At this point, the only company that I know that is making aftemarket camshafts for the XR1200 is Zippers.  Zippers' Redshift 575XR cams are a relatively simple way to gain about 6 HP and about 6 Ft-lbs of TQ.   The 575XR cams work nicely with stock heads, as well as with heads that have been ported and modified.
 
Here are before and after dyno charts of my XR with Zippers 575XR cams.  These charts are off of a Dynojet 150 dyno.  (This is from Zippers engineering dyno, which is a little conservative, but compares nicely with a Dynojet 250i at an indepent shop that I sometimes use.)  A Thundermax ECM is installed - and while there was no extensive tuning done, the TMax had been allowed to "learn" its fuel adjustments for both cams.  The exhaust is a drilled stock exhaust.  ( I also have dyno charts for these cams in my engine, with ported heads and higher compression pistons, which I have posted separately.)
 

XR1200stockvs575XRDyno.JPG
XR1200 (Stock) vs 575XR Dyno

 
The 575XR cams are as close to a "bolt in" cam as is possible.  The stock HD camshaft is spec'd as a .550 lift cam, although Zippers measured out closer to .510 lift.  To install the 575XR cam, the case needs to be clearanced for the taller cam lobes.  Also, Zippers uses a different base circle, so the stock pushrods will not work with the cam.  Either adjustable pushrods or custom measured pushrods are needed.  (I started out with adjustables, and later measured for one-piece pushrods and reinstalled my one-piece pushrod tubes.)  Another significant thing to note is that the stock valve spring seats and locks are too brittle to use with a more aggressive/higher lift cam.  They will crack and drop valves.  So, either a new valve spring set, or higher quality seats and locks need for the stock valves need to be installed.  And of course, once the cams are installed - if you are not running an autotuning ECM - the bike will need to be re-tuned.
 
One other consideration is the fact that the XR1200's camshafts are unique and will not interchange with other Sportster motors.  Also, there is not a huge market for aftermarket cams for the XR1200.  Therefore, Zippers ordinarily makes their Redshift cams for the XR1200, off of customer cores.  This can affect the timeline of a build including a cam upgrade.
 
All in all, once the cam installation is done, the bike does pull stronger through the whole RPM band.  It is a nice upgrade!
 

 
Comparing the Cam Specs
 

 
For comparison, here are the specs on the stock Harley XR1200 cams, and on the Zippers Redshift 575XR cams...
 

 
Stock XR1200 Camshaft Specifications
 

   

Lift

Open

BTDC

Close

ABDC

Duration

Overlap

Lobe Center

ATDC

Lobe

Sep

Lift

TDC

Cam

Offset Deg

XR1200 Camshaft

     (25271-08)

Int

Exh

0.550

0.550

25

60

48

13

252

252

38

101.0

114.0

107.5

?

?

0

Stock (1.62)

   

(Measured
 at
 .510 by Zippers)

BBDC

ATDC

   

BTDC

   

Rocker Ratio

 
Redshift 575XR Camshaft Specifications
 

   

Lift

Open

BTDC

Close

ABDC

Duration

Overlap

Lobe Center

ATDC

Lobe

Sep

Lift

TDC

Cam

Offset Deg

Zippers Redshift

     575XR

Int

Exh

0.575

0.575

26

44

38

20

244

244

46

96.0

102.0

99

0.204

0.172

0

Stock (1.62)

   

.........................

BBDC

ATDC

   

BTDC

   

Rocker Ratio

 
Camshaft Diagrams
 

 
I don't have any pictures of the camshafts themselves, but here are some drawings from the HD Sportster Service Manual showing the camshafts...
 

 
The XR1200's camshafts are unique.  They do not interchange with a regular Sportster.  Hence the reason that Zippers generally makes 575XR cams off of customer cores.
 

Gearcase and Valve Train Components: XR Models
XRCamsincaseblowup.JPG
* From harley Davidson Sportster Service Manual

 
Zippers has a nice stock of cam lobes for the XR cam upgrade.  The 575XR cam is obviously available.  They can also make any other Sportster grind for the XR, e.g. the 567 or 585.  I do not have dyno charts for those cams though.
 

1-camblank.JPG
Camshaft Lobe Blank


 
 
Here is another look at the Xr1200's cam gears, as the camshafts are installed and the timing marks aligned.
 

Cam, Pinion Gear and Timing Mark Indexing: XR Mode
XR1200CamIndexing.JPG
* From Harley Davidson Sportster Service Manual


 
Right now I'm running the 575XR with Zippers CNC ported heads.  The only problem with the build is, I hate to get off the bike at the end of each ride!



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