The Pro Flow oil pump for 1991-up Sportsters was developed by Zippers according to Buz Buzzellie's Sportster Performance Handbook. ¹⁾
Billed as compact Cad/Cam design, made of 6061 aluminum, O-ring sealing throughout and modular construction.
The ProFlow oil pumps and accessories for XLs, BTs and TCs in the year 2000 at least were sold thru Zippers Performance as well as Zodiac International B.V. (The Netherlands)

These pumps are no longer in production. ²⁾ There were two versions for Sportsters; a 3 stage and a 4 stage.
In 2000, the pump was redesigned with improvements, one of which was the addition of an oil strainer cap / cover over the cam chest port. ³⁾
The drive gear and gerotor systems were improved for less drag while maintaining reportedly superior scavenge and feed rates.

The 3-stage pump uses 3 independent gear sections for oil delivery to and fro.
The different stages as starting from the top down;

• The top section has a gerotor stage to scavenge the cam chest. Oil is sucked through the neck by the gerotors in the top section of the pump.
  • Cam chest strainer cap holes: The strainer cap over the cam port has holes in it's upper section for oil intake. There were 3 variations of this strainer; ⁴⁾
    • Street use: holes are pre-drilled in circumference of the upper portion of the cap.
    • Racing: the holes were punched lower down the cap to scavenge all of the oil in the cam chest.
    • Custom: the strainer cap was left blank with no holes so the builder could drill holes to suit needs of the build.
• The middle section has a high volume spur gear stage to scavenge the crankcase sump.
  There is also an extra suction port into the spur gear cavity that is plugged with a 1/8“x27 NPT pipe plug.
  That port can be used if someone for example wants to connect the pump via external plumbing to the sump.
• The bottom section has a gerotor stage that feeds oil to the engine and plumbed just like the OEM pump feed section.
  

Fitment:
This pump is a direct “bolt-on” for 1991-up Sportsters.
It can be installed on 1986-1990 engines with the addition of a feed fitting kit to plumb to the feed passage in the bottom of the engine.
It can also be installed on 1977-1985 engines with the addition of the feed fitting kit which includes feed line plumbing and also an inline check valve.
Further plumbing is the responsibility of the builder.

Click on a pic to enlarge:

Pro Flow 3 stage oil pump. 5)

More pics of the Pro Flow 3 stage oil pump ⁶⁾

The 4 stage pump has an additional set of gerotors utilizing 4 independent gear sections for oil delivery to and fro.
The 4th stage can be used for various things.
Basically, it has 3 independent scavenge sections (draining the rocker boxes, draining a turbo or whatever the engine builder wants)
It is also possible to use the additional stage to pump more feed oil into the motor with additional plumbing.

The different stages as starting from the top down;

• The top section has a gerotor stage to scavenge the cam chest. Oil is sucked through the neck by the gerotors in the top section of the pump.
  • Cam chest strainer cap holes: The strainer cap over the cam port has holes in it's upper section for oil intake. There were 3 variations of this strainer; ⁷⁾
    • Street use: holes are pre-drilled in circumference of the upper portion of the cap.
    • Racing: the holes were punched lower down the cap to scavenge all of the oil in the cam chest.
    • Custom: the strainer cap was left blank with no holes so the builder could drill holes to suit needs of the build.
• The next section down has a high volume spur gear stage to scavenge the crankcase sump.
  There is also an extra suction port into the spur gear cavity that is plugged with a 1/8”x27 NPT pipe plug.
  That port can be used if someone for example wants to connect the pump via external plumbing to the sump.
• The next section down is the additional gerotor (4th) stage and it is plumbed the same as the bottom feed section.
  It has it's own “in and out” fittings separate of the other sections. Plumbed just like the OEM pump feed section.
• The bottom section has a gerotor stage that feeds oil to the engine and plumbed just like the OEM pump feed section.
  

Fitment:
Bolt-on fitment is the same as the 3 stage pump but due to the additional stage, the frame rail has to be modified to accept the taller oil pump.
This pump is a direct “bolt-on” for 1991-up Sportsters.
It can be installed on 1986-1990 engines with the addition of a feed fitting kit to plumb to the feed passage in the bottom of the engine.
It can also be installed on 1977-1985 engines with the addition of the feed fitting kit which includes feed line plumbing and also an inline check valve.
And of course, further plumbing is the responsibility of the builder.

This oil pump is comparable to the 2007-up Sportster oil pump (26204-91A) with the taller scavenge gerotors.
However, the parts in this pump will not interchange with the factory oil pump. The gerotor and middle spacer dims are different.
Click Here to view parts dims for the factory 07-up oil pump.

* Noticeable markings:
… Cover has CL stamped into the bottom center.
… Cover reads RPLS 26204-91A

• Features
  • Cast aluminum body with steel gears and shaft
  • Raw cast aluminum finish
  • Gaskets and seals included
  • (2) mounting bolts and hose clamps (sold separately)
  • (2) 1/8“-27 x 3/8” hose bibb fittings (for feed inlet and return hose attachments) (sold separately)
  • (1) 1/8“-27 x AN5 feed hose fitting (sold separately)

Notes:
Parts Europe lists the flow rate as “standard” ⁹⁾