See also in the Sportsterpedia:
Bendix / Zenith I6P12 (1972-Early 1976) | |
27155-72 1) | 1972- |
27155-72A 2) | 1972-Early 1975 |
27155-72B3) | 1975-Early 1976 |
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.
For example, an “A” stamped into the ID pad away from the HD part# is a Bendix modification letter, not a suffix letter to the HD part#.
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). 4)
Bendix model 13609 and 13731
There were three Bendix carburetors, designated in the parts catalogs, that were installed on Sportsters.
Sportster Year Model | HD Part # | Bendix Part # | Venture Size | No. of Idle Discharge Holes | Idle Tube |
E1972 | 27155-72 5) | 13609A | 36mm | 3 | (A) 27749-72 |
27155-72 6) | 13609B | 36mm 7) | 4 8) | (B) 27750-72 (E72-73) |
|
L1972-1974 | 27155-72A 9) | 13731 | 38mm | 4 | |
1975-Early 1976 (also '71-'75 FL/FLH/FX models) | 27155-72B 10) 11) 12) | 13731 | 38mm | 4 | integrated w / carb body no letter designation not meant for replacement |
Bendix model 13732
Other known Bendix ID information:
HD Part # | Bendix Part # | Venture Size | No. of Idle Discharge Holes |
27152-71 14) | 36mm | ||
27152-71 15) | 13479A | 36mm | 3 |
27152-71 16) | 13479E | 36mm | |
27152-71A 17) | 13732 | 38mm | |
27152-72 18) | 38mm | ||
27155-72B 19) | 36mm | ||
27155-72B 20) | 13731C | 38mm |
Zenith 13859A | Also has the word Andpro. Andrews Products used to sell a Bendix carb. No HD markings |
The venturi size is cast into the venturi. 21)
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.
27155-72 (13609B), arbitrary 'B', venturi stamped 36mm 23) | ||
27155-72B (13731C), arbitrary 'C', venturi stamped 38mm 24) | |
Both of these carbs are stamped 27152-71.
One has a '36' and the other has a '38' stamped inside the venture.
27152-71 (13479A) arbitrary 'A' - venturi stamped '36' 27) | |
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.
The 13609A 36mm carb has 3 idle passages. 33)
The 13609B 36mm carb has 4 idle passages. 34)
The 38mm carbs have 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. 35)
Note that on the adjustable main jet shown below (R), the top of it looks identical to the fixed jet. 36)
Some have converted their fixed main jet setup to an adjustable jet.
The C66-157 fixed main jet came standard on a 1974 Sportster.
The C66-184 adjustable main jet has the tube extending beyond the taper. 40)
Bendix C66-184 adjustable main jet 41) | |
Alternate references include intermediate / idle / low speed jet. The original idle tubes are designated with either an A, B, or C marked on top. 42)
Tube sizes:
These are removable (threaded) jets.
Both the A and B tubes were used on the early 27155-72 (13609B) and 27155-72 (13731) carbs.
Neither the screw type “C” tube nor it's successors were ever installed on a Sportster carb (officially anyway).
72-74 Sportster Fixed Idle Tube: (screw in type - no adjustment)
46) 47)
75-E76 Sportster Fixed Idle Tube: (pressed in type - no adjustment)
Note: Measurements taken on used / removed idle tube from carb #27155-72B (13731C)
48) 49)
Here’s another, and more significant difference. 53)
The cable attachment to the throttle shaft is in a different position which changes the geometry of the cable action.
With the 36 mm carb, the cable pulls from over center with the stock outer jacket bracket.
As you can see in the left picture, even with a modified bracket, the geometry isn’t great.
The picture on the right is the same 36mm carb with the correct throttle shaft and return spring for a 38mm carb added.
The throttle return spring is substantially stronger than the original (for the 36mm).
It also required an additional spring to properly return.
The standard (38mm style) bracket was used to support the outer jacket of the cable.
27155-72B (13731) fixed jet (hidden under welch plug). Also has stampings 'C' and '5 95' 69) | |
Parts listed from the 1962-1973 Sportster Parts Catalog Supplement (99451-73)
Part# | Item | Year |
1214HW | SCREW, No. 10 x 24 x 3/4“ fillister head | 1972 |
3738 | BOLT, throttle cable clamp, 1/4” x 28 x 1/2“ Hex Head | 1972 |
6316W | WASHER, carburetor to manifold stud, 5/16” x 5/8“ x 1/16” (2) | 1972 |
7036 | LOCKWASHER, throttle cable clamp bolt 1/4“ | 1972 |
7725 | LOCKNUT, carburetor to manifold stud, 5/16” x 24 (2) | Late 1972 |
7739 | LOCKNUT, carburetor to manifold stud, 5/16“ x 18 (2) | Early 1972 |
20014-67 | STUD, carburetor to manifold (2) | Early 1972 |
27021-71 | INTAKE MANIFOLD | 1972 |
27023-71 | GASKET, carburetor to intake manifold | 1972 |
27060-55 | 0-RlNG, intake manifold (2) | 1972 |
27063-57 | CLAMP, with screw and buckle (2) | 1972 |
27065-57 | BUCKLE, clamp (2) | 1972 |
27132-71 | REPAIR PARTS AND GASKET KIT | 1972 |
27155-72 | CARBURETOR | 1972 |
27164-71 | ROLL PIN , accelerator pump | 1972 |
27271-71 | SCREW, throttle stop, #8-32 slotted hex head | 1972 |
27272-71 | SPRING, throttle return | 1972 |
27281-71A | THROTTLE SHAFT AND LEVER | 1972 |
27282-71 | THROTTLE PLATE | 1972 |
27326-71 | 0-RlNG | 1972 |
27341-71 | LEVER, accelerator pump | 1972 |
27342-71 | SCREW WITH LOCKWASHER, #1/8-40 (4) | 1972 |
27389-71 | BOOT, accelerator pump | 1972 |
27396-71 | SCREW WITH LOCKWASHER, #4-36 | 1972 |
27403-71 | WASHER, main jet (fiber) | 1972 |
27404-71 | WASHER, idle jet (fiber) | 1972 |
27449-72 | BRACKET, throttle cable with clamp | 1972 |
27612-71 | MAIN JET, 0.90 | 1972 |
27613-71 | SPRING, throttle stop screw | 1972 |
27614-71 | MAINJET, 0.95mm | 1972 |
27618-71 | MAIN JET, 1.00mm | 1972 |
27619-71 | MAIN JET, 1.05mm (standard) | 1972 |
27630-71 | FLOAT | 1972 |
27631-71 | PIN, float | 1972 |
27641-71 | IDLE ADJUSTING SCREW | 1972 |
27642-71 | SPRING, idle adjusting screw | 1972 |
27645-71 | BOWL | 1972 |
27646-71 | GASKET, bowl | 1972 |
27659-71 | SPRING, float | 1972 |
27663-71 | CHOKE PLATE | 1972 |
27664-71 | CHOKE SHAFT AND LEVER | 1972 |
27665-71 | PIN, choke friction spring | 1972 |
27666-71 | FRICTION SPRING, choke | 1972 |
27686-71 | SCREW, wire block, #8-36 (2) | 1972 |
27737-71 | CLIP, fuel valve | 1972 |
27748-71 | FUEL VALVE, with clip | 1972 |
27749-72 | IDLE JET | Early 1972 |
27750-72 | IDLE JET | Late 1972 |
27762-71A | ACCELERATOR PUMP | 1972 |
27763-71 | BOWL DRAIN PLUG | 1972 |
33298-65 | STUD, carburetor to manifold (2) | Late 1972 |
38679-72 | CLAMP, throttle cable bracket | 1972 |
63578-52 | INLET FITIING | 1972 |