See also in the Sportsterpedia:

• Bendix basic carb information
• Bendix Carb Functions, Adjustments, Tuning

There are a lot of Sportsters out there that do not have their original Bendix carb attached to them.
Consequently, this page will try to bring to light at least some the differences in these carbs.
One could say it's a blessing that Bendix carbs for Harleys will interchange.
One could also say it's a curse.
Bendix carbs for Sportsters were set up for Sportsters.
Bendix carbs for other HD models were set up for the needs of those motors.
Changing the jetting alone (on other intended model carbs) to Sportster specs may still not give the results intended.
The 27155-72A Sportster carb has another number stamped into the ID pad (13732).
This Bendix part number denotes a certain configuration carb body and / or internal parts.
Change Letters:
You may have noticed a letter beside the HD part number or it may be arbitrarily stamped in the ID pad away from the HD number.
Carbs with changes made during the build phase had the change letter included at the end of the HD stamped part number.
Carbs with changes made at the dealership (customer owned bikes) had the change letter stamped into the existing ID pad…somewhere.
This explains the arbitrary location of some of the change letters.

Bendix model 13479:

The model 13479 carb was used on FLP, FLH and FX model Harley Davidsons.
The letters A, B, C, D, E and F stamped near the basic Bendix part number (13479) are change letters.
Meaning they denote certain changes made per carb model.

The following changes are noted in Technical Service Bulletin (614A). ¹⁾

• Change for 13479A:
  • The float setting was changed from 1/8“ to 3/16” to remedy a rich condition occurring at steady speeds.
  • The clearance between the float tang and the wire clip on the needle decreased.
    It should be .005“-.010” between the top of the tang and bottom of the portion of spring that hangs over the tang.
• Change for 13479B:
  • A new choke valve has detents with a spring loaded plunger engaging the detents to provide positive positioning throughout the choking range.
  • New part (27664-71 choke shaft replaces 27664-70.
  • New part 27665-71 plunger added.
  • 27666-71 plunger spring added.
• Change for 13479C & 13479D:
  Changes were made to correct over-rich mixtures in the intermediate (off idle) speed range.
  • A new idle jet has two .06mm holes instead of one .08mm hole near the screw end.
    • New part (27725-71) idle jet has the letter 'A' stamped on the screw end and replaces 27723-71.
    • The air bleed hole in the carb body was enlarged from 3.35mm to 3.60mm (app. 9/64: in diameter).

Bendix Sportster carbs:
There were three Bendix carburetors, designated in the parts catalogs, that were installed on Sportsters.

Additionally:

• 27152-71A (13732) - 38mm, was reportedly factory installed on a '74 XLH delivered from the dealer in July 1974. ⁷⁾
• 27152-71 (13479) was a factory Shovelhead carb. ⁸⁾

The venturi size is cast into the venturi. ⁹⁾
Looking in the carb from the air cleaner end, the numbers are on the venturi at 12:00 o'clock on the radiused entry.
They are small but every bendix should have the number stamped there.

¹⁰⁾

Both of these carbs are stamped 27152-71.
One has a '36'.
The other has a '38' stamped inside the venture.

27152-71A (13732) - venturi stamped '38' 11) 12)

27152-71A (13479) arbitrary 'A' - venturi stamped '36' 13)		27152-71 (13479) and an arbitrary 'E' 36mm, fixed jet 14)

27152-71E (13479) arbitrary 'E', 38mm, adjustable jet 15)

Side by side comparison of 36mm and 38mm Bendix carbs.
Aside from the venturi size, the other main difference that might affect the way it runs is the number of secondary idle discharge ports.
These are the holes that get uncovered by the throttle plate at part throttle settings.
The 38mm has 3 (in addition to the idle adjustment screw hole).
The 36 has 2 (in addition to the idle adjustment screw hole).
The air cleaner screw bosses on the 36mm are smaller.

(Left) 38mm, (Right) 36mm 16)	36mm doesn't have a bowl vent hole here 17)	(L) 38mm has a flat corner, (R) 36mm is round 18)

The 36mm carb has 3 idle passages. ¹⁹⁾
The 38mm carb has 4 idle passages.

One feature of an adjustable main jet, (besides the number), is the holes near the bottom that are drilled at about a 45° angle. ²⁰⁾
Note that on the adjustable main jet shown below (R), the top of it looks identical to the fixed jet. ²¹⁾

²²⁾

Some have converted their fixed main jet setup to an adjustable jet.

The C66-157 fixed main jet came standard on a 1974 Sportster.

Bendix Carb Main Jet C66-157 - 1.10mm 23) 24)

The C66-184 adjustable main jet has the tube extending beyond the taper. ²⁵⁾

Bendix C66-184 adjustable main jet 26)

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