== carb ID#   S C O O T E R S   a n d   M O T O R C Y C L E S
  8. PA 29C-D  1984-87 Honda NQ50, NB50 xxxxx   30 mph TS
14. PB 15A-A  1982-83 Honda C70 Passport xxxxx  xxxxx  OHC

Scooters

8. Keihin PA 29C-B on #GK8 ‘84-85 Honda NQ50 Spree (US)
8. Keihin PA 29C-D on #GK8 1985   Honda NQ50 Spree (US)
8. Keihin PA 29D-A on #GK8 ‘84-85 Honda NQ50 Spree
8. Keihin PA 29D-B on #GK8 1985   Honda NQ50 Spree
8. Keihin PA 29H-A on #GE8,GN2 1983-85 Honda NB50 Aero 50

1983 Honda NB50M Aero

1985 Honda NQ50 Spree

#0 16100-GK8-673 Keihin PA 29C-D

#0 16100-GN2-601 Keihin PA 04H-A

#0 16100-GN2-633 Keihin PA 046-A

#0 16100-GE8-013

Flange Mount: The flange mount holes on ’84-87 Spree carburetors are spaced 35mm, center-to-center. That is different from ’74-78 PC50 32mm, ’82-83 NC50-AA 36mm, ’77-83 NC50 38mm, ’79-on Z50 32mm, and ’76-78 Z50 38mm.

These were zippy 50cc two-stroke automatic scooters that maxed out at 30mph to meet many US state’s moped laws. They have electric start so there is 12 volt battery power to operate an automatic electric choke. They also have a gas gauge and an automatic vacuum petcock on the gas tank. You don’t have know very much to operate one. They had a CVT variator that continuously changes the belt drive pulley size ratio, for very quick acceleration. 

Idle Mixture Screw: The idle mixture screw is an “air screw” that blocks off an air channel.

Main Jet: The main jet is a screw-in, recessed-type, M6-0.75 thread, size 68 (0.68mm).

Pilot Jet: The idle jet is not replaceable. It is inside the upper end of the brass tube, pressed into the main body, on the engine side of the main jet.

Float Seat: This carb does not have a replaceable float needle valve seat. The seat is part of the main body, and must be cleaned and polished with a spinning Q-tip.

Float: non-stirrup type white plastic 16013-147-004 see 6-4.0b, non-stirrup needle valve 16155-883-005 see 6-2.0b

Top Cap: M18 x 1 thread

The float bowl gasket in the illustration looks like the NC50-type, but it’s not. The actual gasket has an additional loop, for a vent and overflow. 

 quantity
o# ⇓⇓⇓⇓       Keihin PA (a)29C-B  (b)29C-D   (c)29D-A   (d)29D-B
o# abcd price  Honda part#x  Spree carburetors
o0 1000  N/A  16100-GK8-671
o0 1000  N/A  16100-GK8-672 PA29C-B ’84-85 NQ50, NQ50-A (US)
o0 0100  N/A  16100-GK8-673 PA29C-D      ’85 NQ50, NQ50-A (US)
o0 0010  N/A  16100-GK8-731
o0 0010  N/A  16100-GK8-732 PA29D-A ’84-85 NQ50-AA (US 25 mph)
o0 0001  N/A  16010-GK8-733 PA29D-B      ’85 NQ50-AA (US 25 mph)
o0 1000  N/A  16100-GK8-871 PA000-0      ’86 NQ50-A
o0 1000  N/A  16100-GK8-881 PA000-0      ’86 NQ50-AA
o# abcd price  Honda part#x  Spree carburetor parts
o1 1111  $21 16010-GE8-305 gasket solo-set   1b 1c 1g 1v 1w
o1 1111  $21 16010-GK8-003 gasket solo-set   1b 1c 1g 1v 1w
o1 1111  $22 16010-GE8-315 gasket multi-set 1b 1c 1g 1v 1w 1x
1b 1111  $$8 00000-000-000 top rubber washer 13 x 16.5 x 1
1c 1111  $$2 00000-000-000 intake o-ring 2 x 20 (24 od) 
1g 1111  $$2 00000-000-000 drain plug o-ring 1.5 x 4 (7 od)
1v 1111  $19 00000-000-000 float bowl gasket  2.5 x 1.5 with loop
1w1111    $2 00000-000-000 choke bystarter o-ring 1 x 16 (18 od)
1x 0000  N/A  00000-000-000 choke o-ring (some) 1 x 12 (14 od)
20 1100  N/A  99101-187-0680 jet 68   30mph versions
20 0011  N/A   99101-187-0650 jet 65   25mph version AA

o0 0000  N/A 16100-GE8-672
o0 0000  N/A 16100-GE8-673 carburetor PA040-0 ’83-84 NB50M (US)
o0 0000  N/A 16100-GE8-003 carburetor PA040-0      ’84 NB50M (DK)
o0 0000  N/A 16100-GE8-013 carburetor PA040-0      ’84 NB50M (DK)
o0 0000  N/A 16100-GE8-601 carburetor PA040-0      ’84 NB50M (UK)
o0 0000  N/A 16100-GE8-611 carburetor PA040-0      ’84 NB50M (DE)
o0 0000  N/A 16100-GE8-621 carburetor PA040-0      ’84 NB50M (FR)
o0 0000  N/A 16100-GE8-671 carburetor PA040-0      ’84 NB50M (CA)
o0 0000  N/A 16100-GN2-601 carburetor PA040-0      ’85 NB50M (UK)
o0 0000  N/A 16100-GN2-602 carburetor PA04H-A      ’85 NB50M (UK)
o0 0000  N/A 16100-GN2-621 carburetor PA040-0      ’85 NB50M (FR)
o0 0000  N/A 16100-GN2-622 carburetor PA040-0      ’85 NB50M (FR)
o0 0000  N/A 16100-GN2-633 carburetor PA046-A      ’85 NB50M (US)
o0 0000  N/A 16100-GN2-671 carburetor PA040-0      ’85 NB50M (CA and US)
o0 0000  N/A 16100-GN2-672 carburetor PA040-0      ’85 NB50M (US)
o0 0000  N/A 16100-GN2-871 carburetor PA040-0      ’86 NB50
o0 0000  N/A 16100-GN2-872 carburetor PA04P-A      ’86 NB50 (US)
o0 0000  N/A 16100-GN2-762 carburetor PA04W-A      ’87 NB50 (US)

Motorcycles

14. Keihin PB 15A-A on #GB4  1982-83 Honda C70 Passport (US)

Keihin PB15A-A

Flange Mount: 36? mm hole spacing

   quantity
o# ⇓       Keihin PB (a)15A-A
o# a price  Honda part#x  description xxx specs
o0 1  N/A 16100-174-673 carburetor PB 15A-A 1980   C70  Passport (US)
o0 1  N/A 16100-174-772 carburetor PB 15A-A 1981   C70  Passport (US)
o0 1  N/A 16100-GB5-671 carburetor PB 15A-A ’82-83 C70 Passport (US)
o1 1  N/A 16010-GB4-013 gasket solo-set
o1 1  N/A 16010-141-305 gasket multi-set

== carb ID# =========  M I N I   C Y C L E S  =========
  9. PA   Z502  1968-71 Honda Z50A Mini Trail xx 00 mph OHC
10. PA 655-A  1972-75 Honda Z50A Mini Trail xx oo mph OHC
10. PA 674-A  1970-75 Honda QA50 xxx oooo xx 00 mph OHV
11. PA 03A-A  1976-78 Honda Z50A Mini Trail xx oo mph OHC
11. PA 03C-A  1979-81 Honda Z50R
11. PA 03D-A  1982-85 Honda Z50R
11. PA 03F-B  1986-87 Honda Z50R
12. PA 03H-A  1988-91 Honda Z50R
12. PA 03H-B  1988-91 Honda Z50R
12. PA 03M-A  1992-99 Honda Z50R
12. PA 03N-A  1992-99 Honda Z50R
13. PA 42A-C  2000-03 Honda XR50R
13. PA 42A-C  2004-09 Honda CRF50F

9. Keihin Z50A on #045 1968-69 Honda Z50A Mini Trail up to Z50A-255950
9. Keihin Z502 on #045 1969-71 Honda Z50A Mini Trail after Z50A-255950 

Keihin Z50A, Z502

Keihin Z50A, Z502 on 1968-71 Z50A

1968-71 Z50A carb kit

Flange Mount: 32mm hole spacing, 2 x 18 (22 od) o-ring

Main Jet: This carb has a screw-in main jet size 50.

Pilot Jet: It also has a screw-in idle (pilot) jet size 38.

Float Seat: It also has a screw-in float needle seat, replaceable.

Float: no-stirrup metal-tip needle valve, metal swinging float

The Z50A and Z502 carbs are the same except for the needle jet #12 and rubber cable pipe #10.

10. Keihin 655-A on #130 1972-75 Honda Z50A Mini Trail
12. Keihin 674-A on #114 1970-72 Honda QA50
12. Keihin ceto and #129 1973-75 Honda QA50

Keihin 655-A on 1972-75 Z50A

1974-75 Z50A carb kit, missing the drain plug o-ring and jet pad disk.
1970-73 Z50A carb kit also had a float seat and a float seat washer.

Flange Mount: 32mm hole spacing, no o-ring groove on carburetor. Instead the o-ring groove is on the intake manifold. Since the 2 x 18 (22 od) intake o-ring is not part of the carburetor, it is not in the Honda gasket set 16010-114-004, or the multi-app set 16010-114-305.

Main Jet: This carb has a “long” press-in jet, with a rubber pad disk under it.

Pilot Jet: The idle jet is not replaceable. It is inside the upper end of the brass tube, pressed into the main body, on the engine side of the main jet.

Float Seat early: The 1970-73 carburetor had a screw-in float needle seat, that was replaceable, like in the illustration.

Float Seat late: The 1974-75 carburetor did not have a replaceable float needle valve seat. The seat was part of the main body, and must be cleaned and polished with a spinning Q-tip.

Float: no-stirrup metal-tip needle valve, swinging float 16013-114-004

Top Cap: M18 x 1.0 thread

Drain screw: 1970-73 chamber set 16015-114-004 had a M4-0.7 thread drain screw with a 2 x 4 (8 od) o-ring. 1974-75 had a M6-0.75 thread drain screw with no o-ring. 1976-78 had a M6-1.0 thread drain screw with a 2 x 2.5 (6.5od) o-ring. 1979-later had a 1.5 x 4 (7od) drain screw o-ring.

Keihin 655-A, 674-A

   quantity
o# ⇓⇓    (a) 655-A  (b) 674-A
o# ab price  Honda part#x  description xxx specs
o0 10  N/A 16100-120-010 carburetor 655-A Ø?? ’72-75 Z50A
o0 01  N/A 16100-000-000 carburetor 674-A Ø?? ’70-75 QA50
o1 11  $24 16010-114-004 gasket solo set 1d 1e 1h 1n 1p 1r
o1 00  $24 16010-114-305 gasket multi set 1d 1e 1h 1n 1p 1r 1q
1d 11 0$2 16176-551-004 main jet o-ring 1 x 3 (5 od)
1e 11 $13 16197-063-004 jet support disk Ø7.5 x 1.8
1h 11 $$2 00000-000-000 intake o-ring 2 x 18 (22 od)
1n 11 0$3  16173-063-004 float bowl o-ring 1.5 x 40 (43 od)
1p 11 0$5 16171-044-004 top rubber washer 10 x 15 x 1
1r  11 0$5 16175-001-004 drain screw o-ring 2 x 4 (8od)

16010-114-004

1972 Z50A drain screw

11. Keihin (10 mm) PA 03A-A on #130 1976-78 Honda Z50A Mini Trail
12. Keihin (11 mm) PA 03B-A on #181 1979-79 Honda Z50R up to 5022291
12. Keihin (11 mm) PA 03C-A on #181 1979-81 Honda Z50R after 5022291
12. Keihin (11 mm) PA 03D-A on #181 1982-85 Honda Z50R
12. Keihin (11 mm) PA 03F-B on #181 1986-87 Honda Z50R  

In 1979 the model name changed from Z50A to Z50R, and the name Mini Trail was dropped.

#0  16100-130-642
Keihin PA 03A-A
for 1976-78 Z50A
from cmsnl.com

#0  16100-165-004
Keihin PA 03B-A
for 1979 Z50R

#0 16100-165-014
Keihin PA 03C-A
for 1979-81 Z50R
from cmsnl.com

#0  16100-181-751
Keihin PA 03D-A
for 1982-85 Z50R

#1 16010-181-832
Keihin PA 03F-B
for ’86-87 Z50R
from cmsnl.com

1976-78 Z50A carb kit
D348 thick needle, #58 push-in jet. 
The drain screw and jet support pad are missing.

1979-81 Z50R carb kit
D117 thin needle, #58 screw-in jet. Left to right: drain screw, needle jet (emulsion tube), idle air screw, idle speed screw, float needle

Flange Mount: 38 mm hole spacing 1976-78.  32 mm hole spacing 1979-87.

Pilot Jet: The idle jet is not replaceable. It is inside the upper end of the brass tube, pressed into the main body, on the engine side of the main jet.

Main Jet:  For some reason in 1979 Honda wanted to make their jets tamper-proof. It’s funny that they went from one extreme to the other, from jets that fall out too easy, to jets that never come out. Both the NC50 and the Z50 changed to “fixed” jets (not replaceable) in late 1978 and 1979. After 1981 the jet was a screw-in, thankfully, like in the illustration

Float Seat: This carb does not have a replaceable float needle valve seat. The seat is part of the main body, and must be cleaned and polished with a spinning Q-tip.

Carb Kit: Beware of low-cost carburetor kits. In the kit at the right several things are wrong or made badly. 1) it is missing the press-in jet pad disk, 2) the jet o-ring was too big to allow the jet to press in. You can see it seems big in the photo. It was size 1.5 x 4 instead of 1 x 3, 3) the float needle was longer than stock, and the wire stirrup was bent badly in two ways. The throttle (jet) needle was D117 thin instead of D348 thick.

Float: In 1979 the float and float needle changed, from stirrup-type needle valve with black foam float, to no-stirrup needle valve 16155-883-005 with white plastic float 16013-147-004. Like before, the float needle has a rubber cone upper tip and a spring-loaded lower tip. 

Float Bowl: The 1979-later float bowl no longer has a press-in jet support pad disk 7.5 x 1.8mm.

16010-081-004

#1  16010-143-305

#1  16010-081-014

#1 16010-165-621

#1 16010-181-305

PA 03A, 03B, 03C, 03D, 03F

   quantity
o# ⇓⇓⇓⇓    PA(a)03A-A  (b)03B-A  (c)03C-A  (d)03D-A  (e)03F-B
o# abcde price  Honda part#x  description xxx specs
o0 1o0oo  N/A 16100-130-641 use 16100-130-642
o0 1o0o0  N/A 16100-130-642 carburetor PA 03A-A Ø10 x 38 ’76-78 Z50A
o0 o1000  N/A 16100-165-004 carburetor PA 03B-A Ø11 x 32 ’79-79 Z50R
o0 o0100  N/A 16100-165-014 carburetor PA 03C-A Ø11 x 32 ’79-81 Z50R
o0 oo010  N/A 16100-181-751 carburetor PA 03D-A Ø11 x 32 ’82-85 Z50R
o0 00001  N/A 16100-181-830  16100-181-831 use 16100-181-832
o0 00001  N/A 16100-181-832 carburetor PA 03F-B Ø11 x 32 ’86-87 Z50R
o1 1o000 $28 16010-081-004 gasket solo-set   1a o d e f o h i
o1 10000 $28 16010-143-305 gasket multi-set 1a c d e f o h i
o1 01100 $22 16010-081-014 gasket solo-set   1a o o o f g h
o1 00011 $23 16010-165-621 gasket solo-set   oo o o o f g h o l
o1 01111 $23 16010-181-305 gasket multi-set 1a o o o f g h o l
1a 1o000 $$3 00000-000-000 top rubber washer 10 x 18 x 1
1d 1o0o0 0$2 16176-551-004 main jet o-ring 1 x 3 (5 od)
1e 10000 $13 16197-063-004 jet support pad disk Ø7.5 x 1.8 
1f  11111 $18 00000-000-000 float bowl gasket  Ø1.5 NC50-type
1g o1111 $$2 00000-000-000 drain screw o-ring 1.5 x 4 (7 od)
1h 11011 $$2 00000-000-000 intake o-ring 2 x 18 (22 od)
1i  10000 0$2 16175-260-004 drain screw o-ring 2 x 2.5 (6.5 od)
1l  01111 0$4 16110-181-831 top rubber washer 13 x 19 x 1
02 10000  N/A 16012-130-640 needle set 03AA
02 010o0  N/A 16012-165-014 needle set 03BA use 16012-181-831 
02 00111  N/A 16012-181-831 needle set 03CA, 03DA, 03FB
03 1o000  N/A 16013-099-691 use 16013-143-620
o3 1o000  $46 16013-143-620 float set 3a oo 3c 3d black stirrup
o3 o1111 $28 16013-147-004 float set oo 3b 3c 3d white regular
3a 1o000  N/A 00000-000-000 float bare, solid black foam stirrup
3b o1111 $21 00000-000-000 float bare hollow white plastic regular
3c 11111 $$4 00000-000-000 hinge pin substitute Ø2 x 18.5
3d 11111 $$3 0-93600-04006 hinge screw M4x6 sunk phillips
o4 11100  N/A 16014-130-640 top set with pipe 4a 1a M18-1.0
o4 00011  N/A 16014-GB1-912 top set with pipe 4a 1l M20-1.0
05 1o000  N/A 16015-130-640 chamber set 5a 1e 1f 5b 1g
05 o1110  N/A 16015-099-691 chamber set 5a oo 1f 5b 1g
05 o???1  N/A 16015-130-641 use 16015-130-641
05 o???1  N/A 16015-165-621 chamber set 5a oo 1f 5b 1g
6a ????1  N/A 16016-165-621 use 16016-165-505
6a ????1  N/A 16016-165-505 idle air screw set
6b ????1  N/A 16208-GC8-004 idle speed screw set
07 ?????  N/A  slide set
09 ?????  N/A  rubber cable pipe cover
10 1o0oo  N/A 16011-143-620 use 16011-881-741
10 1o0oo $21 16011-881-741 float needle valve  stirrup
10 o1111 $22 16155-883-005 float needle valve regular
11 22222 0$1 93892-04012-08 screw & washer M4x12 pan phillips
14 10000 $16 99201-081-0580 main jet push-in #58 0.0228″
14 01100  N/A fixed needle jet and main jet pressed in 0.0228″
14 00011 0$7 99101-187-0580 main jet screw-in #58 0.0228″
18 11111  N/A (not sold separately) idle jet press-in tube 0.015″ pinhole

12. Keihin PA 03H-A on #GW8 1988-88 Honda Z50R up to JS900485
15. Keihin PA 03H-B on #GW8 1988-91 Honda Z50R after JS900485
15. Keihin PA 03M-A on #GW8 1992-93  Honda Z50R
15. Keihin PA 03N-A on #GW8 1994-99  Honda Z50R

#0 16100-GW8-682 Keihin PA 03M-A

#0 16100-GW8-305  Keihin PA 03N-A  from cmsnl.com

Flange Mount: 32mm hole spacing

Main Jet: screw-in #58, M6-0.75

Float: no-stirrup type white plastic 16013-147-004, needle valve 16155-883-005

Top Cap: M20-1.0 thread

Idle Mixture Screw: For the entire Z50A and Z50R year range 1968 to 1999, the idle mixture screw was an air type, not a fuel type. An idle air screw blocks an air tunnel, so tighter is less air (richer). An idle fuel screw blocks off a fuel tunnel. So tighter is less fuel (leaner). 

1992-98 Z59R carb kit

#1  16010-181-831
for PA 03H 03M 03N

#1  16010-181-305
for PA 03H 03M 03N

#5  16016-GW8-672
This idle air screw looks
like an idle fuel screw.

Keihin PA 03H-A, PA 03H-B, PA 03M-A, PA 03N-A

   quantity
o# ⇓⇓⇓⇓  Keihin PA (a)03H-A  (b)03H-B  (c)03M-A (d)03N-A
o# abcd price   Honda part#x   description xxx specs
o0 1000  N/A 16100-GW8-671 16100-GW8-672 carburetor PA 03H-A 1988 Z50R up to JS900485
o0 0100  N/A 00000-000-000  16100-GW8-673 carburetor PA 03H-B ’88-91 Z50R mix screw changed
o0 0010  N/A  -680  -681 000  16100-GW8-682 carburetor PA 03M-A ’92-93 Z50R
o0 0001  N/A  -780  -791 000  16100-GW8-792 carburetor PA 03N-A ’94-99 Z50R
o0 1111  N/A 00000-000-000  16100-GW8-305 multi-carb  PA 03N-A replacement
o1 1111 $23 16010-181-831  gasket solo-set   o0 1f 1g 1h 1l
o1 1111 $23 16010-181-305  gasket multi-set 1a 1f 1g 1h 1l
1f  1111 $18 00000-000-000  float bowl gasket  Ø1.5 NC50-type
1g 1111 $$2 00000-000-000  drain plug o-ring 1.5 x 4 (7 od)
1h 1111 $$2 00000-000-000  intake o-ring 2 x 18 (22 od)
1l   1111 0$4 16110-181-831  top rubber washer 13 x 19 x 1
02 needle set
03 float set
04 chamber set
05 idle air screw set
06 slide set
07 idle speed screw set
09 top set
10 float needle
11 float bowl screw
12 drain hose
13 drain hose clamp
14 main jet

13. Keihin PA 42A-C on #GEL  2000-03 Honda XR50R
16. Keihin PA 42A-A on #GEL  2000-03 Honda XR50R
16. Keihin PA 42A-A on #GEL  2004-09 Honda CRF50F

In 2000 the Z50R was replaced by the XR50R. The carburetor remained mostly the same.

Links to Images:
2000 Honda XR50R carburetor PA42A-C
2008 Honda CRF50F carburetor  The gasket for this was in use for over 34 years!

This carburetor looks the same as the previous Z50R ones, except the flange is thicker and has square corners, not rounded.

Flange Mount: 32mm hole spacing, thicker with square corners

Chinese re-makes of this carburetor are common on the internet, at incredibly low prices. Read several reviews before buying one. Try to re-use the original Keihin.

In 2004 the XR50R was replaced by the CRF50F. The carburetor remained mostly the same.

Service: Here is a good article about how to remove and clean the non-replaceable idle (pilot) jet.

https://thumpertalk.com/forums/topic/1047667-clogged-pilot-jet-on-a-crf50-success/

The CRF50F idle jet in that article did not crush when gripped lightly with a vise grip pliers. But some pressed-in idle jets have thin walls, or have a tighter fit that needs heavy clamping. Those require a close-fitting drill bit or solid wire, be placed in the hole first, to prevent crushing the tube with the vise grips. It’s a good idea to do that always. 

==============  K E I H I N   P A R T S  ===========
15. Float needles
16. Float bowls
17. Gaskets and O-rings
18. Jets 

15.  Float needles (valves)

Baby valves: These are the float needle valves for the smallest “baby” Keihin carburetors. Most other float needles are bigger than these, but look the same in photos.

16123-063-004 float needle valve $13  all metal type
On road models: 1969-70 Honda PC50, 1969-70 Honda PS50, 1970-72 Honda PC50K1, 1971-73 PF50 Amigo standard (FR DK NE), 1971-73 PF50 Amigo Graduate (UK), 1970-71 PS50K1, PS50K1 (NE), others

16011-881-741 float needle valve $21 stirrup type, 3-sided for 4.00 hole
supersedes 16011-143-62016011-147-004
On road models: 1977-79 Honda NC50 Express (with PA08B-A carb), 1978-79 PA50I and PA50II Hobbit, 1976-78 Z50A Mini Trail  Off road: 1976-78 Honda Z50A, 1977-79 XL75, 2004-07 CR80F, 1976-78 XR75, 1979-84 XR80, 1985-03 XR80R, 1977 CT125, 1976 TL125

16155-883-005 float needle valve $22 regular type, 3-sided for 4.00 hole
On road models: 1973-77 Honda PC50K1, 1973-78 Honda PF50 Amigo/Novio, 1978-83 Indian AMI-50, 1979-83 Honda NC50 Express (with PA08B-B carb), 1980-83 PA50II Hobbit, 1979-81 NA50 Express II, 1981-82 NX50 Express SR, 1982-83 NU50 Urban Express, 1980-83 C70 Passport, 1978-79 CT90 Trail 90, 1986 CT110 Trail 110, 1982 MB5, 1990 NS50, 1984-85 NQ50 Spree, 1988-90 SA50 Elite 50, 1985-91 CH80 Elite 80  Off road: 1979-99 Honda Z50R, 1988 ZB50, 2000-03 XR50R, 2004-12+ CRF50F, 2004-09, CRF70F, 1978-82 CT70, 1997-03 XR70R, 1978-79 Honda CT90, 1980-84 CT110

Valve seats: The seat is the hole that the needle tip seals against. These “baby” Keihin PA series carbs have non-replaceable valve seats. Most motorcycle carburetors have replaceable float valve seats that screw in or push in. The seat is normally replaced with the needle. With these the seat must be cleaned, polished and inspected. It’s a tiny round hole at the end of a dark small round tunnel. It’s hard to see. It must be perfectly circular with no nicks or scratches on the edge of the hole, where it seals against the rubber cone tip of the needle.  The walls of the tunnel must be clean, smooth and shiny or the float might stick open a little and cause an overflow leak.

Beware of low cost float needles (valves). These have to be made precisely the same as originals in order to function properly. In the photo, the left one is a 16011-991-741 generic low-cost replica, made incorrectly. The stirrup wire is bent and the needle is longer. The right and middle are 16011-991-741 Honda originals (or KL-made replicas) for comparison, made correctly. 

Chamber families 165, 147A, 191, GK8

16.  “baby” Keihin float bowls

Here the chamber sets from above are all listed together, along with the carbs and bikes they go on. A chamber set includes the float bowl, float gasket, drain screw, and drain screw o-ring. As a courtesy, here are the links to CMS in Netherlands where you can view their image and see their price and availability.

Families: A chamber set family is one or more chamber sets that can interchange.

Jet pad: Before about 1980 these carburetors had push-in main jets. The push-in main jet was supported by a pill size rubber pad. The jet pad was held by a circular wall in the bottom of the float bowl. You can see that in the image on the right. The second bowl is for a jet pad, but the first bowl is not.

Choke jet: Carbs with fuel enrichment  type chokes have a jet in one corner of the float bowl (2nd, 3rd, and 4th in the image). Carbs with air valve choke plates do not have a choke jet (first in the image).

  Float Bowls (chambers) with no choke jet  =================    chamber     gasket

16015-064-004                                064 family
cmsnl.com roundish shape, shallow for jet pad, no choke jet
on carbs C4A C5A C5B F4A F5A lever-plate choke
on bikes 69-70 PC50/PS50, 70-73 PC50K1/PS50K1, 71-73 PF50

16015-114-004                                114 family
cmsnl.com roundish shape, deep for jet pad, no choke jet
on carbs 655A 674A lever-plate choke
on bikes 72-75 Z50, 70-75 QA50

16015-081-004                                081 family
cmsnl.com NC50-shape, shallow for jet pad, no choke jet
on carbs PA00A PA01A lever-plate choke
on bikes 73-77 PF50R, 73-78 PC50K1

16015-130-640  
 cmsnl.com NC50-shape, shallow, for jet pad, no choke jet
on carbs PA03AA lever-plate choke
on bikes 76-78 Z50A, 79-81 Z50R and other Z50’s

16015-099-691                                165 family
cmsnl.com NC50-shape, shallow, for no jet pad, no choke jet
on carbs PAM0A PA03HA PA03HB PA03MA others lever-plate choke
on bikes 78-83 Indian, 88-99 Z50R, 04-05 CRF50F many others

16015-130-641 ⇒ 16015-165-621
 cmsnl.com NC50-shape, shallow, for no jet pad, no choke jet
on carbs PA03CA PA03DA lever-plate choke
on bikes 80-85 Z50R

same

16015-165-920 ⇒ 16015-165-621
 cmsnl.com NC50-shape, shallow, no jet pad, no choke jet
on carbs
on bikes

16015-165-621 ⇒ 16015-165-B10
 cmsnl.com NC50-shape, shallow, for no jet pad, no choke jet
on carbs PA03FB lever-plate choke
on bikes 86-87 Z50R

same

16015-165-B10
 cmsnl.com NC50-shape, shallow, for no jet pad, no choke jet
on carbs PA03?? lever-plate choke
on bikes 93-96 Z50J (Japan model)

  Float Bowls (chambers) with choke jet  =================    chamber     gasket

16015-147-004                                147A family
  cmsnl.com NC50-shape, shallow, for jet pad, with choke jet
on carbs PA08BA  black float, cable-enrich choke
on bikes 77-78 NC50

16015-147-014                                 147B family
 cmsnl.com  NC50-shape, shallow, for no jet pad, with choke jet
on carbs PA08BB 08EA 08EB 08DA white float cable-enrich choke
on bikes 78-80 NC50, 79-80 NA50

same

16015-187-043 use 16015-191-034  191 family
 cmsnl.com NC50-shape, deep, for no jet pad, with choke jet
on carbs PA13EA                 white float vacuum-enrich choke
on bikes 82-83 NU50, NU50M

16015-187-671 use 16015-191-034
 cmsnl.com NC50-shape, deep, for no jet pad, with choke jet
on carbs PA13BA                 white float vacuum-enrich choke
on bikes 81-82 NX50

16015-191-014 ⇒ 16015-191-024
 cmsnl.com NC50-shape, deep, for no jet pad, with choke jet
on carbs PA15AA PA16AA  white float vacuum-enrich choke
on bikes 81 NC50, 81 NA50

same

16015-191-024 ⇒ 16015-191-034
 cmsnl.com NC50-shape, deep, for no jet pad, with choke jet
on carbs PA15AA PA16AA  white float vacuum-enrich choke
on bikes 81 NC50, 81 NA50

16015-191-034   available soon
  cmsnl.com NC50-shape, deep, for no jet pad, with choke jet
on carbs PA15AA PA16AA  white float vacuum-enrich choke
on bikes 81 NC50, 81 NA50

16015-GA6-671 use 16015-191-034
treatland.tv NC50-shape, deep, for no jet pad, with choke jet
on carbs PA13EA                 white float vacuum-enrich choke
on bikes 82-83 NC50

16015-GK8-671                                GK8 family
  cmsnl.com  NC50 with outer loop, very deep, choke jet
on carbs PA29CD PA29HA others electric-enrich choke
on bikes 84-86 NQ50, 83-85 NM50

17.  Gasket Multi-App Sets (for several carburetors)

There are 100’s of vintage Honda carburetors. Many share the same gaskets, but have maybe one or two things different. To reduce the number of different gasket sets, Honda combines several sets into one multi-set. In a multi set there are extra “optional” gaskets, that may or may not be needed. These are in separate packages labeled A or B. There is a sheet of paper with a table of replacement gasket set part numbers, the specific part numbers they replace, and a number, usually 1 or 0, in the A and B columns, telling how many of each “optional” gaskets are required.  

16010-114-305

16010-114-305 $20
fits 1972-75 Honda Z50A (minus 2 x 18 o-ring)
fits 1970-75 Honda QA50
1p top rubber washer 10 x 15 x 1  
1q (A) drain screw washer 3 x 6 x 0.5
1d main jet o-ring 1 x 3 (5 od)
1e jet support disk Ø7.5 x 1.8? 
1n float bowl gasket 1.5 x 40 (43 od) 
1r drain plug o-ring 2 x 4 (8 od)

16010-143-305

16010-143-305 $28    
fits 1976-78 Honda Z50A Mini Trail, 1979-81 Z50R
fits 1977 NC50 Express and some 1978 (except for the drain plug o-ring)
fits 1970-77 PC50K1 and 1978-80 Indian AMI50 (except drain plug o-ring)
1a top rubber washer 10 x 18 x 1
1h (A) intake o-ring 2 x 18 (22 od) 
1c (B) intake o-ring 2 x 20 (24 od) 
1d main jet o-ring 1 x 3 (5 od)
1e jet support disk Ø7.5 x 1.8 
1f  float bowl gasket Ø1.5 NC50 type
1i  drain plug o-ring 2 x 2.5 (6.5 od)

16010-147-505

16010-147-505 $24 
fits 1979 NC50 and some 1978
fits 1979-80 NA50 and NC50
fits 
1b top rubber washer 13 x 16.5 x 1
1c intake o-ring 2 x 20 (24 od)
1d (A) idle fuel screw o-ring 1 x 3 (5 od)
1g (A) drain plug o-ring  1.5 x 4 (7 od)
1f  float bowl gasket Ø1.5 NC50 type
1i  (B) drain plug o-ring 2 x 2.5 (6.5 od)

16010-156-305

16010-156-305 $15   
fits 1978-83 Honda PA50
1c intake o-ring 2 x 20 (24 od)
1w intake o-ring 2.5 x 24 (29 od)
1g drain plug o-ring  1.5 x 4 (7 od)
1j float bowl gasket 2 x 50 (54 od)

16010-181-305

16010-181-305 $23  
fits 1979-86 Z50R, 2000-03 XR50R, 2004-11+ CRF50F
1a top rubber washer 10 x 18 x 1
1h intake o-ring 2 x 18 (22 od)
1l  top rubber washer 13 x 19 x 1 
1g drain plug o-ring  1.5 x 4 (7 od)
1f float bowl gasket Ø1.5 NC50 type

16010-GE8-315

16010-GE8-315   
fits 84 NB50M, 82-85 NJ50M, 84-86 NQ50, NQ50M
1b top rubber washer 13 x 16.5 x 1
1c intake o-ring 2 x 20 (24 od)
1y (A) o-ring 1 x 12.5 (14.5 od)
1z (B) o-ring 1 x 16 (18od)
1g drain plug o-ring  1.5 x 4 (7 od)
1k float bowl gasket 2.5 tall x 1.5 wide NQ50 type

16010-GF8-305

16010-GF8-305 $25  
fits 1981-82 NX50, 1982-83 NU50
1b top rubber washer 13 x 16.5 x 1
1h intake o-ring 2 x 18 (22 od)
1d (A) idle fuel screw o-ring 1 x 3 (5 od)
1t (B) o-ring 1.5 x 8.5 (11.5 od)
1u (B) nylon washer 6.2 x 11 x 0.8
1g drain plug o-ring  1.5 x 4 (7 od)
1k float bowl gasket 2.5 tall x 1.5 wide NQ50 type

1a rubber washer 10 x 18 x 1
1b rubber washer 13 x 16.5 x 1
1c o-ring 2.0 x 20 (24 od) 
1d o-ring 1.0 x 3 (5 od)
1e jet disk Ø7.5 x 1.8?
1f  float gasket Ø1.5 NC50 type
1g o-ring  1.5 x 4 (7 od)
1h o-ring 2.0 x 18 (22 od)
1i  o-ring 2.0 x 2.5 (6.5 od)
1j o-ring 2.0 x 50 (54 od)
1k float gasket 2.5 tall x 1.5 wide NQ50 type
1l  rubber washer 13 x 19 x 1 
1n o-ring 1.5 x 40 (43 od)
1p rubber washer 10 x 15 x 1  
1q fiber washer 3 x 6 x 0.5
1r o-ring 2.0 x 4 (8 od)
1s
1t o-ring 1.5 x 8.5 (11.5 od)
1u nylon washer 6.2 x 11 x 0.8
1v float bowl gasket  2.5 x 1.5 with loop
1w o-ring 2.5 x 24 (29 od)
1x o-ring 1.0 x 12 (14 od)
1y o-ring 1.0 x 12.5 (14.5 od)
1z o-ring 1.0 x 16 (18 od)

18. Jets

99201-081-0700

  ∅ 5   P U S H – I N    J E T S   ∅5.0 x 9.5 with o-ring 1 x 3 (5 od)
===========================================
 N/A 99201.081.0500 jet push-in 50
 N/A 99201.081.0520 jet push-in 52
 N/A 99201.081.0550 jet push-in 55 C4A C4B F4A C5A
$16 99201.081.0580 jet push-in 58 PA 03A-A
 N/A 99201.081.0600 jet push-in 60
 N/A 99201.081.0620 jet push-in 62 C5B F5A
$16 99201.081.0650 jet push-in 65 PA 01A
 N/A 99201.081.0680 jet push-in 68 
$16 99201.081.0700 jet push-in 70 PA 00A
 N/A 99201.081.0780 jet push-in 78 PA 08B-A
$23 substitute jet, #70 drilled to 78 PA 08B-A

99201-122-0750

  ∅ 5   P U S H – I N    J E T S   ∅5.0 x 9.5 with o-ring 1 x 3 (5 od)
===========================================
N/A 99201.122.0650 jet push-in 65 PA 06A
N/A 99201.122.0700 jet push-in 70
N/A 99201.122.0750 jet push-in 75 006A, PA 07A

99101-187-0700

M 6   S C R E W – I N   J E T S    M6-0.75 thread
===========================================
0$7 99101-187-0580 jet #58 PA03DA PA03FB 82-87 Z50R
 N/A 99101-187-0600 jet #60
 N/A 99101-187-0640 jet #64
0$7 99101-187-0680 jet #68 PA29CD PA29HA 84-87 NQ50
$$7 99101-187-0700 jet #70 PAMOA PA25A ? 78-80 Indian, 82-83 NC50I
0$7 99101-187-0750 jet #75 PA15A 16A 13BB 81-83 NC50, 81 NA50
0$7 99101-187-0760 jet #76
0$7 99101-187-0780 jet #78 PA13BA 81-82 NX50
0$7 99101-187-0800 jet #80
 N/A 99101-187-0820 jet #82 
0$7 99101-187-0850 jet #85 PA13EA 82-83 NU50

99101-124-0700

M 7   S C R E W – I N   J E T S    M7-0.75 thread
===========================================
$7.00 99101-124-0600 main jet 60 BB21A
$7.00 99101-124-0780 main jet 78 BB20A

19. Where else to get Keihin parts

Consolidated Motor Spares B.V. (CMS): This is an excellent online store from the bike-loving nation of Netherlands that has “every” Honda part. They have parts schematic illustrations for every Honda model worldwide, and photos of every part on every Honda, and not just motorcycles. And not just Honda, but also Kawasaki, Suzuki, and Yamaha. Much of the information of the Honda “Baby” Keihin carburetors came from CMS. https://www.cmsnl.com/ 

== carb ID# ============  M O P E D S  ===========
3. PA 00A-A  1973-77 Honda PC50K1, PF50R ooo 50 kmh OHV
3. PA 01A-A  1973-77 Honda PC50K1, PF50R ooo 40 kmh OHV
3. PA M0A-A  1978-83 Indian AMI50 4-Stroke xx  30 mph OHV
4. BB 21A-B  1978-78 Honda PA50-I Hobbit xxx   20 mph TS
4. BB 21A-F  1979-79 Honda PA50-I Hobbit xxx   20 mph TS
4. BB 20A-C  1978-78 Honda PA50-II Hobbit xx    30 mph TS
4. BB 20A-F  1979-83 Honda PA50-II Hobbit xx    30 mph TS
5. P 006A-A  1974-75 Honda MR50 Elsinore xxx   40 kmh OHC
5. PA 06A-A  1973-78 Honda PM50, PF50M xxxx   40 kmh TS
5. PA 07A-A  1975-78 Honda PF50M xxxxxxxxx    50 kmh TS

3. Keihin
size   carb   years  model code   models00xx   speed version
0∅9 PA 01A 1973-77 081 Honda PC50K1 00xxxxxx  40 km/h
0∅9 PA 01A 1973-78 099 Honda PF50 Amigo/Novio 40 km/h
∅10 PA 00A 1973-77 081 Honda PC50K1 00xxxxxx  50 km/h
∅10 PA 00A 1973-78 099 Honda PF50 Amigo/Novio 50 km/h
∅10 PA M0A 1978-81 000 Indian AMI-50 (US) xxxx   30 mph

  
1. ’73 Honda PC50K1, 2. ’80 Indian AMI-50 (US), 3. ’73-78 Honda PF50 Amigo line

   
1. ’75 Honda PC50K1, 2. ’80 Indian AMI-50 (US), 3. Keihin PA-00A carb, 4. Missing the jet pad #1e.

 
1. #0 16100-081-024 Keihin PA-00A carb, 2. #0 Keihin PA-M0A carb

Late PC50: In 1973 the PC50 carburetor changed from “donut” float to a swinging float, and a NC50-type float bowl and gasket. The 1973-77 PC50K1 and 1973-78 PF50 engine and carb are the same as the Taiwan remake engine and Keihin carburetor used on the 1978-83 Indian moped. So the carburetor parts are the same also, with some exceptions.

PA 00A (16100-081-024) and PA 01A (16100-099-693) have the same parts. The push-in jet size, venturi size and intake flange o-ring are the only difference. 

PA M0A (E210-20-50) has the same parts as PA 00A and PA 01A, except for 1) a screw-in jet instead of push-in, 2) no jet pad, 3) no jet pad holder in float bowl, 4) a white regular type float instead of a black stirrup type. 

Flange Mount: 32 mm hole spacing, 2 x 18 (22 od) o-ring 00A, 01A.

Indian AMI50: The Indian AMI50 Chief four stroke moped engine, OHV with pushrods and internal pedals, made from 1978-1984, is a Taiwan-made copy of a Honda PC50K1 or PF50 engine, OHV with pushrods and internal pedals, made from 1973-1978. The Indian had three different carburetors, Tillotson (some 1978), Keihin (some 1978, most 1979-80), Mikuni (some 1980, all 1981-84). Only the Keihin parts are listed here.

1. left, #0 Keihin PA-M0A carb, 2. right, #0 generic PA-M0A carb

   
1. #1  16010-081-004 carburetor gasket set for PA 00A and 01A
2. #1  16010-143-305 carburetor multi-set for PA 00A, 01A, 03A
3. #1  16010-081-014 carburetor gasket set for PA M0A
4. #1  16010-181-305 carburetor multi-set for PA M0A, 03C, 03D, 03E, 03F

quantity
o# ⇓⇓⇓    Keihin  (a)PA-00A  (b)PA-01A  (c)PA-M0A
o# abc price Indian part#  Honda part#    description        specs
00 100  N/A 0000-00-00 16100-081-024 carburetor PA 00A Ø10 E10
00 010  N/A 0000-00-00 16100-099-693 carburetor PA 01A   Ø9 E10
00 001  N/A  E210-00-50 16100-000-000 carburetor PA M0A Ø10
00 111 $75  E000-00-00 16100-000-000 carb generic new Ø10, jet 70 screw-in
00 111 $50  E000-00-00 16100-000-000 carb generic new no top, slide, needle
o1 110 $28 0000-00-00 16010-081-004 gasket solo-set   1a o d e f g h
o1 110 $28 0000-00-00 16010-143-305 gasket multi-set 1a c d e f o h i
o1 oo1 $22 E231-gasks  16010-081-014 gasket solo-set   1a o o o f g h
o1 001 $23 E231-gasm  16010-181-305 gasket multi-set 1a o o o f g h i  l
1a 111 $$3 E231-####00000-000-000 top rubber washer 10 x 18 x 1
1c 000 $$2 E231-####00000-000-000 intake o-ring 2 x 20 (24 od) 
1d 11o 0$2 0000-00-00 16176-551-004 main jet o-ring 1 x 3 (5 od)
1e 11o $13 E231-####16197-063-004 jet pad disk Ø7.5 x 1.8 
1f  111 $18 E231-02-00 00000-000-000 float bowl gasket Ø1.5 NC50-type
1g oo1 $$2 E231-11-00 00000-000-000 drain screw o-ring 1.5 x 4 (7 od)
1h 11o $$2 0000-00-00 00000-000-000 intake o-ring 2 x 18 (22 od)
1i  110 0$2 0000-00-00 16175-260-004 drain screw o-ring 2 x 2.5 (6.5 od)
02 110 $21 0000-00-00 16011-881-741 float needle valve  stirrup type
02 oo1 $22 E231-13-00 16155-883-005 float needle non-stirrup type
03 111  N/A E231-####16012-081-014 needle set 3a 3b 3c 3d
3a 111 $10 E231-09-00 00000-000-000 jet needle D348 thick Ø2 x 33
3b 111 0$2 E231-10-00 16157-044-004 needle e-clip substitute 1.5mm
3c 111 0$5 E231-08-00 16156-044-004 w-spring clip
3d 111  N/A E231-####16133-081-004 needle jet ∅3.95 ∅5 ∅3.9 ∅5 x 27
3d ooo 0$6 0000-00-00 ooooo-000 03A needle jet ∅3.95 ∅5 ∅3.9 ∅5 x 27
3d ooo 0$6 0000-00-00 ooooo-000 03B needle jet ∅3.95 ∅5 ∅3.9 ∅5 x 27
o4 110  N/A E231-####16013-099-691 float set black 4c 4d 4e PA 00A, 01A
4a 001 $28 E231-####16013-147-004 float set white 4b 4d 4e PA M0A
4b 001 $21 E231-06-00 00000-000-000 float bare white non-stirrup
4c 110  N/A E231-06-00 00000-000-000 float bare black stirrup
4d 111 $$4 E231-15-00 00000-000-000 hinge pin substitute Ø2 x 18.5
4e 111 $$3 E231-16-00 0-93600-04006 hinge pin screw M4 x 6 sunk
05 111 $30 E231-01-00 16014-081-004 top set 5a 5b 1a
5a 111 $23 E231-03-00 00000-000-000 substitute cap brass M20-1.0
5b 111 0$3 E231-####00000-000-000 cable adjuster male M6-0.75
06 11o  N/A E231-01-00 16015-081-004 chamber set 6a 6b 1f 1i
6a 11o  N/A 0000-00-00 16015-165-B10 float bowl bare for push-in jet
06 oo1 $67 E231-####16015-099-601 chamber set 6a 6c 1f 1g
6a oo1 $46 E231-01-00 16015-165-B10 float bowl bare for screw-in jet
6b 11o  N/A 0000-00-00 00000-000-000 bowl drain screw M4-0.70
6c oo1 $16 E231-23-00 00000-000-000 bowl drain screw M6-1.00
07 111 $15 E231-####16016-143-620 adjustment screw set 7a 7b 7c 7d
7a 111 $$9 E231-19-00 00000-000-000 idle air mix screw M6-0.75 special
7b 111 $$4 E231-21-00 00000-000-000 idle speed screw M4-0.70 special
7c 111 $$7 E231-20-00 00000-000-000 idle air screw spring Ø4.9 x 10
7d 111 $$2 E231-22-00 00000-000-000 idle speed screw spring Ø5.6 x 10
08 1o1 $34 E231-####16022-081-004 valve set 8a 8b Ø13 PA 00A
08 1o1 $00 E231-####16022-HB2-003 new #
8a 1o1 $22 E231-07-00 00000-000-000 throttle slide Ø13 #15A PA 00A
8b 1o1 $12 E231-17-00 00000-000-000 throttle spring Ø10 x 42 PA 00A
08 o1o  N/A 0000-00-00 16022-143-620 valve set 8a 8b Ø12 PA 01A
08 o10 $00 0000-00-00 16022-191-004 new #
11 111 0$2 E231-04-00 16118-086-004 rubber boot substitute Dellorto
12 222 0$1 E231-12-00  93500 – 04012 bowl screw M4 x 12 pan phillips
13 222  .25 E231-####   95002-02070 bowl screw lock washer
14 111  N/A E231-####   95001-35150 drain hose
15 111  N/A E231-####0-95002-02070 drain hose clamp
16 oo1 $$7 E231-18-00 99101-187-070 main jet #70 M6-0.75 screw-in
16 oo1  N/A E231-18-00 99201-187-0700 new #
16 11o $16 0000-00-00 99201-081-070 main jet #70 0.0275″ push-in
16 11o  N/A 0000-00-00 99201-081-0700 new #
17 oo1  N/A E231-01-00 00000-000-000 carb body bare
18 oo1  N/A E231-####00000-000-000 idle jet press-in tube 0.38 mm=0.015″

Indian PA MOA carb disassembled

Choke plate: These three carbs have a lever choke that swings a plate to block air flow. There is no enrichment fuel path or jet. So the float bowl has no choke jet. The other baby Keihins with cable or vacuum operated choke do have a choke jets in their float bowls. The choke (enrichment) fuel passes up through the sealed off corner of the bowl gasket.  

Float Bowl: The PA-03A and 03B chamber set (float bowl, float bowl gasket, drain screw and drain screw o-ring) from 1970’s Honda mini-cycles (Mini Trail or Monkey) interchanges with a PA 00A, 01A chamber set  from 1970’s Honda mopeds. The drain screw (4 or 6 mm) and its o-ring (2×2.5 or 1.5×4) are different. So if the float bowl is changed the drain screw must also be changed. 

Needle jet: The PA-03A and 03B mini-cycle needle jets (emulsion tubes) interchange with PA 00A, 01A, and M0A moped ones. These press out with taps from a hammer and punch from above. At first the punch tip needs to be bigger than the 4 mm tube end. Once the tube end gets below the floor a smaller 3.5 to 3.9 mm straight round bar is needed. It has to enter the 4 mm hole and contact the idle tube around the edge.

Keihin MOA parts

Idle jet: A little downstream from the needle jet is the idle jet. It is a pinhole 0.015″ at the upper end of a vertical brass tube about 20mm long. The idle tube is a press fit in the carb body. Some can be pulled out with just a pliers. Some might be tighter and require a drill bit be placed inside the tube to prevent crushing from the tighter pliers grip. This tube was never intended to be replaced and is not sold or included in any common carb kit. 

Air tunnels: In the front below the main air inlet are two small horizontal air tunnels. The center tunnel is main air and the side tunnel is idle air. The small amount of air sucked in through the main air tunnel passes through tiny holes in the emulsion tube and becomes thousands of microscopic air bubbles in the liquid gasoline that is being drawn upward. The tiny amount of air sucked in through the idle air tunnel passes around the idle air adjustment screw cone shape tip and goes to the vertical idle passage just above the idle jet. The idle air tunnel is the size of a regular paper clip 0.036 inch. A straightened paper clip cleans it perfectly.    

PA50 speed versions

4. Keihin
∅10 BB 21A-B #148 on 1978-78 Honda PA50 I  Hobbit (US) 20 mph
∅10 BB 21A-F #148 on 1979-79 Honda PA50 I  Hobbit (US) 20 mph
∅12 BB 20A-C #148 on 1978-83 Honda PA50 II Hobbit (US) 30 mph

1978 PA50II 30mph

1978 PA50I 20mph

1983 Honda PA50II

#0 16100-148-645  Keihin BB 21A-B

#0  16100-148-646 Keihin BB21A-F

#0  16100-148-708  Keihin BB 20A-C

Flange mount: 42 mm bolt hole spacing

Honda’s successor to the four-stroke PC50 was the two-stroke PA50, known in the USA as Hobbit, and in Europe as Camino. It was made in Belgium by Honda Benelux, so it had a mix of Japanese and European design and componentry. 

In US models, 20 mph versions were 1978-79 red. 30 mph versions were 1978-79 yellow, 1980 yellow, 1981-82 red, and 1983 black.

This Keihin BB type carburetor is not like any other moped carburetor. It looks more like a Honda generator carburetor. It is a very flat design. It has to be special because it swings up and down with the engine, and is very close to the frame at the place where you step through.  The BB type floats on PA50 are wider and flatter than NC50 or Z50 floats.  

#1  16010-124-760

#1  16010-156-305

Keihin BB-20A and BB-21A

  quantity
o# ⇓⇓⇓⇓  (a)BB 21A-B (b)BB 21A-F (c)BB 20A-C (d)BB 20A-F
o# abcd price  Honda part# x description xxx specs
00 1o00  N/A 16100-148-645 carburetor 21A-B ∅10 20 mph 1978 
00 01o0  N/A 16100-148-646 carburetor 21A-F ∅10 20 mph 1979
00 o010  N/A 16100-148-708 carburetor 20A-C ∅12 30mph 1978
00 o001  N/A 16100-148-708 carburetor 20A-F ∅12 30mph’79-83 
01 1111 $14 16010-124-760 gasket solo-set   1c 1g oo 1j
01 1111 $15 16010-156-305 gasket multi-set 1c 1g 1w 1j
1c 1111 $$2 00000-000-000 intake o-ring 2 x 20 (24 od)
1g 1111 $$2 00000-000-000 drain screw o-ring 1.5 x 4 (7 od)
1j  1111 $11 00000-000-000 float bowl gasket 2 x 50 (54 od)
o2 1010  N/A 16011-147-004  16011-147-305
o2 1010 $21 16011-881-741 float needle stirrup type
o2 0101 $22 16011-883-005 float needle regular type
03 1010  N/A 16013-124-760
03 1010  N/A 16013-124-762 float set black 3a 3c 21A-B, 20A-C
03 0101  N/A 16013-883-305 float set white 3b 3c 21A-F, 20A-F?
3a 1010  N/A 00000-000-000 float bare black stirrup type
3b 0101  N/A 00000-000-000 float bare white regular type
3c 1111  N/A 00000-000-000 hinge pin ∅2 x 23
04 1111  N/A 16016-148-611 screw set
04 1111  N/A 16016-890-015 screw set 4a 4b 4c 4d 4e
4a 1111 0$1 00000-000-000 idle speed screw M4 x 15 slot
4b 1111  N/A 00000-000-000 idle speed spring
4c 1111  N/A 00000-000-000 idle fuel screw
4d 1111  N/A 00000-000-000 idle fuel spring
4e 1111 0$3 00000-000-000 cleaning access plug M5 x 5 slot
05 1111  N/A 16024-124-760 drain screw set
07 1111  N/A 16110-148-010 choke lever cover
08 1111  N/A 16166-148-740 nozzle, main
09 1111  N/A 16199-148-611 vent hose ∅3.5 ∅6.5 x 65 gray
09 1111  .50 16199-148-sub substitute  ∅3.1 ∅6.3 x 65 clear
10 1111 0$2 0-93500-04008 cable pinch screw M4 x 8
11 2222 0$1 0-93500-04012 bowl screw M4x12 pan phillips
12 2222  .50 0-94111-04800 lock washer M4 split
13 1111  N/A 95001-35400-40 drain hose ∅3.5 ∅7.0 x 400 gray
13 1111 0$1 95001-35400sub substitute ∅3.1 ∅6.3 x 400 clear
14 1010 0$7 99101-124-600 main jet 60 21A
14 0101 0$7 99101-124-780 main jet 78 20A
15 1111  N/A 0-95002-02070 drain hose clamp B7 (for 7 not 6.3)
16 1111  N/A 0-95002-02065 vent hose clamp B6.5

PA50 carb removal

 Servicing: The best way to remove the PA50 carburetor is to hold the back of the bike up by either a rope tied to an overhead beam, or with a milk crate and blocks of wood. Remove the floorboards and side covers. Unplug the ignition wires from the coil at the right rear. Pull them through and move them out of the way. Disconnect the decompression cable and the spark plug cap. Loosen the wiring clamps so there is slack in the wires. Remove the lower rear shock bolts and the swing arm pivot bolt above the engine. Then the whole sub-frame can be moved away from the main frame, either by lifting the back of the bike up, or by swinging it around sideways.

Note that the float bowl can go on two different ways. The wrong way assembles normally, but causes the vertical brass overflow tube to contact the float. Honda designed all of the cleaning ports, drain screws, and adjustment screws to face the right side of the bike, which is the upper left in the exploded view. The drain hose spigot on the float bowl faces the same way as the adjustment screws. The other way to tell is by shaking the carburetor. If you can hear the float rattling inside then the float is not stuck so the float bowl is on correctly. 

While every other moped carburetor is a sliding throttle valve type, this one is a swinging plate throttle valve. The reason is to be flatter, to get more clearance from the bottom of the frame. The manual choke is also a swinging plate, with an automatic release.

Some servicing can be done with the carburetor installed. It is easy to clean the idle passages and jet by spraying a one second long burst of carb spray into the idle mixture screw hole, followed by compressed air. The running engine is allowed to consume the flammable solvent before the next burst is sprayed in, to prevent the engine from getting flooded.

1975-78 PF50M

5. Keihin
size carb model code years       Honda models
∅12   006A on #131 1974-75 MR50 Elsinore (US)
∅10 PA06A on #122 1973-75 PM50 Canguro, PM50 Novio  40 km/h
∅10 PA07A on #143 1975-78 PF50M, PF50MR (BE,NL,NZ) 40 km/h
∅12 PA07A on #143 1975-78 PF50M, PF50MR (FR,UK,CA) 50 km/h

1973 Honda PM50 Canguro

1974 Honda PM50 Novio

#0 16100-131-004 Keihin 006A

#0  16100-122-024 PA06B

#0  16100-143-620 Keihin PA07A

Flange mount: PA06A PA07A 32 mm bolt hole spacing
Spigot-mount: 006A

Cable-choke: The choke cable passes through the carb top along with the throttle cable.  

Float: These carbs have a black float 16003-114-004 but a non-stirrup type float needle. The float needle and seat are sold as a set 16011-122-004.

#1  16010-131-004

#1  16010-122-305

Keihin PA06A-A and PA07A-A

  quantity
o# ⇓⇓⇓    Keihin    (a)006A   (b)PA06A   (c)PA07A
o# abc price  Honda part# x description xxx specs 
00 10o  N/A 16100-131-004 carburetor ∅12 006A   74-75 MR50
00 o00  N/A 16100-122-004
00 o00  N/A 16100-122-014 carburetor ∅10 696A
00 o00  N/A 16100-122-024 carburetor ∅10 PA06B
00 01o  N/A 16100-122-690 carburetor ∅10 PA06A PM50 < 20101
00 01o  N/A 16100-122-691 carburetor ∅10 PA06A PM50 > 20100
00 01o  N/A 16100-122-692 carburetor ∅10 PA06A PM50 > 20100
00 o01  N/A 16100-143-620 carburetor ∅12 PA07A PF50M, PF50MR
00 10o  N/A 16010-131-004 gasket solo-set   5-piece 1a d e f o i
01 011  N/A 16010-122-004 16010-122-014
01 011  N/A 16010-122-305 gasket multi-set 7-piece 1a d e f h i s
1a 111  N/A 00000-000-000 top gasket Ø1.5
1d 111 0$2 16176-551-004 main jet o-ring 1 x 3 (5 od)
1e 111 $13 16197-063-004 jet pad disk Ø7.5 x 1.8 
1f  111  N/A 00000-000-000 float bowl gasket Ø1.5
1h 011 $$2 00000-000-000 intake o-ring 2 x 18 (22 od)
1i  111 0$2 16175-260-004 drain screw o-ring 2×2.5(6.5od)
1s 111  N/A 00000-000-000 float valve o-ring 1.5 x 5 (8od)
96 011  N/A 99201-122-0650 main jet push-in #65 PA06A
96 100  N/A 99201-122-0750 main jet push-in #75 006A PA07A?

== carb ID# ============  M O P E D S  ===========
1. 50A, 50B– 1966-68 Honda P50 xxxxxxxxxxxx  40 kmh OHC
1. 610 (50B) 1967-68 Honda P50 Little Honda     40 kmh OHC
2. C4B, C5B   1969-70 Honda PC50A xxxxxxx  40,50 kmh OHC
2. C5A, C5A   1969-70 Honda PC50 Little Honda   40 kmh OHC
2. S4A, S5A   1969-70 Honda PS50  xxxxooo x 40,50 kmh OHC
2. F4A, F5A   1970-73 Honda PC50K1, PF50 x  40,50 kmh OHV
2. S4B, S5B   1970-71 Honda PS50  xxxxxxxxooo  50 kmh OHV 

1. Keihin 
carb model code years  frame number range      models
50A-000 #044 1966-67 P25-A000001-00000 Honda P25
50A-610 #044 1967-68 P50-100001-148606 Honda P50
50A-610 #044 1967-68 P50-100001-148606 Honda P50 Little Honda (US)
50B-NL   #044 1967-68 P50-128651-148606 Honda P50 (Netherlands)
50B-000 #044 1968-68 P50-148607-000000 Honda P50
50B-000 #044 1968-68 P50-148607-000000 Honda P50 Little Honda (US)

1964 P25 (NL model)

1967 Honda P50

1968 P50 (US model)

Bore:  42.0 mm, stroke 35.6 mm, displacement: 49.3 cc. P50’s have down-draft carburetors, unusual.
50B carbs do not have a replaceable float valve. It’s part of, and only sold with, the float chamber cover.
50B has a larger carb size ∅11? and  jet #68 or 62. 50A has a smaller carb size ∅9? and jet #60 or 55.

#0  16010-044-004

#1  16010-044-680

Honda P50 carburetors

  =00 quantity   Keihin
0#=00 ⇓⇓⇓⇓   (a)50A(b)50A-610  (c)50B-N  (d)50B
0#=00 abcd  price   Honda part#   description        specs
00=00 1000  N/A 16100-044-030
00=00 1000  N/A 16100-044-315 carburetor 50A-000 ’66-67
00=00 0100  N/A 16100-044-405 carburetor 50A-610 ’67-68
00=00 1100  N/A 16010-044-004 gasket set 10-piece 4 12 13
00=00 1100  N/A 16010-044-004 15 20 20 20 24 27 32
00=00 1100  N/A 16151-044-681 jet needle
11=00 1100  N/A 16125-044-004 float valve set
12=00 1100  N/A 16173-001-004 rubber seal ring
13=00 1100  N/A 16188-044-004 valve fiber washer 7.2 x 10.5
16=00 1000  N/A 16133-044-004 needle jet
16=00 0100  N/A 16133-044-681 needle jet 2.6 x 1.55
17=00 1000  N/A 0-99144-03804 slow jet 38
17=00 0100  N/A 0-99144-03504 slow jet 35
24=00 1100  N/A 16123-044-004 jet access gasket
25=00 1000  N/A 0-99120-06014 main jet 60
25=00 0100  N/A 0-99120-05514 main jet 55
26=00 1100  N/A 16112-044-004 float chamber cover
30=00 4400 0$1 0-93600-04008 sunk-phillips screw M4 x 8
32=00 1100  N/A (not sold separately) choke shaft o-ring
=======================================
00=00 0010  N/A 16100-044-681 carburetor 50B-NL ’67-68
00=00 0001  N/A 16100-044-683 carburetor 50B-00 1968
01=00 0011  N/A 16010-044-680 gasket set 4-piece 4 15 20 27
1n=27 1111 0$3 16174-044-004 float o-ring 1.5 x 40 (43od)
1p=04 1111 0$5 16171-044-004 top rubber washer 10 x 15 x 1
1r=15 1111 0$5 16175-001-004 needle jet o-ring  2 x 4 (8od)
1i =20 3333 0$2 16175-260-004 jet/screw o-ring 2 x 2.5 (6.5od)
02=00 0011  N/A 16012-044-681 needle set 2a 2b 2c 2d
2a=06 1111 0$5 16156-044-004 throttle w-clip
2b=07 1111 0$2 16157-044-004 needle e-clip 1.5 for 2.0 needle
2c=00 0011  N/A 16151-044-683 jet needle
2d=00 0011  N/A 16133-044-683 needle jet 2.6 x 2.0
03=00 1111  N/A 16014-044-004 top set 3a 3b 1p
3a=03 1111  N/A 16119-044-004 carb top M16-1.0
3b=02 1111 0$3 16118-044-004 cable adjuster male M6-0.75
04=00 0011  N/A 16015-044-014 chamber/valve set 4a 1n
4a=00 0011  N/A 16112-044-014 chamber cover w/valve
05=00 1111  N/A 16016-044-014 screw set 5a 5b 5c 5d 1i 1i
5a=18 1111  N/A 16163-044-014 idle speed screw
5b=19 1111  N/A 16162-259-004 idle air screw
5c=21 1111  N/A 16182-011-004 idle speed spring
5d=22 1111  N/A 16181-202-004 idle air spring
06=00 0011  N/A 16022-044-680 valve (slide) set 6a 6b
6a=09 1111  N/A 16141-044-683 throttle valve (slide)
6b=05 1111  N/A 16185-044-004 throttle spring
10=00 0022  .80 00-93500-03008 phillips screw M3 x 8
13=00 0o10  N/A 99114-044-0681 main jet 68
13=00 00o1  N/A 00-99120-06214 main jet 62
14=00 0011  N/A 99203-044-5201 slow jet

Part Sets: Before 1968 most Honda parts were sold individually. That is how the top carb is listed and illustrated. Starting in 1968, many Honda parts were only sold in sets. That is how the bottom carb is listed and illustrated. 

Parts for the top carb that are the same as the bottom, are only listed in the bottom carb parts.

2. Keihin
size carb model code eng  years    frame number range      Honda models
0∅9  C4A on #063 ohc 1969-70 PC50-1000000 to 1057917   PC50 xxxxxx40 km/h
∅10  C5A on #063 ohc 1969-70 PC50-1057918 to 1060412   PC50 (1306302) 50 km
∅10  C5A on #063 ohc 1969-70 PC50-1060413 to 0000000   PC50 Little Honda (US)  
∅10  C5A on #064 ohc 1969-70 PS50-1000000 to 1001412   PS50 xxxxxx50 km/h
∅10  S5A on #064 ohc 1969-70 PS50-1001413  to 0000000   PS50 xxxxxx50 km/h
0∅9  C4B on #081 ohv 1970-71 PC50-2000000 to 2039616   PC50K1 xxxx40 km/h
∅10  C5B on #081 ohv 1970-71 PC50-2039617 to 0000000   PC50K1 xxxx50 km/h
∅10  S5B on #082 ohv 1970-71 PS50-2000000  to 0000000   PS50K1 xxxx50 km/h
0∅9  F4A on #081 ohv 1971-73 PC50-0000000 to 0000000   PC50K1 xxxx40 km/h
∅9 o F4A on #099 ohv 1970-73 PF50-1000000 to 0000000   PF50 Amigo  40 km/h
∅10  F5A on #081 ohv 1971-73 PC50-0000000 to 0000000   PC50K1 xxxx50 km/h
∅10  F5A on #099 ohv 1970-73 PF50-1000000 to 0000000   PF50 Amigo  50 km/h

1968 PC50A (Euro)
with OHC engine

1969-70 PC50 (USA) with OHC engine

1973 Honda PC50K1
with OHV engine

1969-70 PC50: Before April 1970, the PC50 had a OHC engine (over head cam). Bore 42.0 mm, stroke 35.6 mm, displacement 49.3 cc. The valves were operated by a cam in the head, driven by a cam chain.

Spigot mount: The Keihin C4A, C5A, C4B, C5B carburetors for the early 1969-70 PC50A were spigot mount type. They had a round float bowl gasket (with three flat sides when installed), a push-in jet, jet pad, completely round “donut” float, all metal float needle with replaceable float seat.

1970-73 PC50K1: After April 1970, the PC50K1 had a OHV engine (over head valve). The valves were operated by pushrods from a cam down in the case.

Flange mount: The Keihin F4A, F5A, carburetors for the 1970-73 PC50K1 were flange mount type with 32mm bolt spacing. There was a diamond shaped gasket rather than an o-ring like all later flange mount carbs. Everything else was the same, round float bowl gasket (with three flat sides when installed), a push-in jet, jet pad, completely round “donut” float, all metal float needle with replaceable float seat.

Keihin C5A carburetor

Keihin F4A carburetor

#1 16010-063-000
1d 1e 1n 1p     1r

#1 16010-063-004
1d 1e 1n 1p 1q   .

#1 16010-114-305
1d 1e 1n 1p     1r 1v

Keihin C4A, C4B, C5A, C5B

0o quantity
o# ⇓⇓⇓⇓⇓⇓  Keihin (a)C4A (b)C5A (c)C4B (d)C5B (e)F4A (f)F5A
o# abcdef  price   Honda part#    description       specs
00 100000  N/A 16100-063-690 carb. C4A   ∅9  69-70 PC50
00 010000  N/A 16100-063-004 carb. C5A ∅10  69-70 PC50, PS50
00 001000  N/A 16100-081-690 carb. C4B   ∅9  70 PC50K1 < 2039617
00 000100  N/A 16100-081-014 carb. C5B ∅10  70 PC50K1 > 2039616
00 000010  N/A 16100-099-690 carb. F4A   ∅9  70-73 PC50K1, PF50
00 000001  N/A 16100-099-600 carb. F5A ∅10  70-73 PC50K1, PF50
01 111011 $25 16010-063-004 gasket solo-set   1d 1e 1n 1p 1q
01 000100 $17 16010-063-000 gasket solo-set   1d 1e 1n 1p oo 1r
01 000100 $20 16010-114-305 gasket multi-set 1d 1e 1n 1p 1q 1r
1d 111111 0$2 16176-551-004 main jet o-ring 1 x 3 (5 od)
1e 111111 $13 16197-063-004 jet pad disk Ø7.3 x 1.9
1n 111111 0$3  16173-063-004 float bowl o-ring 1.5 x 40 (43 od)
1p 111111 0$5 16171-044-004 top rubber washer 10 x 15 x 1
1q 111011 0$9 16189-056-004 drain screw seal washer 6 x 8 x 0.5
1r  000100 0$5 16175-001-004 drain screw o-ring C5B 2 x 4 (8od)
02 001101  N/A 16012-064-004 needle set F5A 2a 2c 2d 2f
2a 111101  N/A 16051-063-004 jet needle C4A C5A C4B C5B F5A
2b 000010  N/A 16051-063-690 jet needle F4A
2c 111111 0$5 16156-044-004 needle w-clip
2d 111111 0$2 16157-044-004 needle e-clip 1.5 for 2.0 needle
2e 110000  N/A 16133-063-004 needle jet C4A C5A 2.1 x 2.5
2f  001101  N/A 16133-081-004 needle jet C4B C5B F5A
2g 000010  N/A 16133-081-690 needle jet F4A
03 111111  N/A 16013-064-004 float set 3a 3b 3c 3d 3e 10
3a 111111  $13 16123-063-004 float needle (all metal)
3b 111111  N/A 16122-063-004 float
3c 111111  N/A 16127-063-014 float arm
3d 111111  N/A 16126-063-014 float hinge pin
3e 111111  N/A 16196-063-014 float pin plate
04 111111  N/A 16014-064-004 top set 4a 4b 1p
4a 111111  N/A 16119-063-004 top with pipe
4b 111111  N/A 16118-045-004 cable adjuster female M6-0.75
05 111011  N/A 16015-064-004 chamber set 5a 5c 1n 1q
05 000100  N/A 00000-000-000 chamber set 5b 5d 1n 1r
5a 111011  N/A (not sold separately) chamber bare
5b 000100  N/A (not sold separately) chamber bare
5c 111011  N/A 16164-225-004 drain screw C4A C5A C4B F4A F5A
5d 000100  N/A 16162-304-004 drain screw C5B
06 111111  N/A 16016-063-004 adjustment screw set
6a 111111  N/A 16163-063-014 idle speed screw
6b 111111  N/A 16162-044-004 idle air screw & spring
6c 111111  N/A 16181-250-004 idle speed spring
07 111111  N/A 16022-063-004 throttle valve set
7a 111111  N/A 16141-063-004 throttle valve (slide)
7b 111111  N/A 16185-044-004 throttle spring
09 111111  N/A 16194-063-004 cable pipe cover
10 222222 $1.00 93500-0300500A phillips screw M3 x 5
11 222222 $1.00 93500-040120A phillips screw M4 x 12
12 111111 $0.50 94111-030000 spring washer M3
13 222222 $0.20 94111-04000 spring washer M4
15 101010  N/A 99201-063-0550 main jet #55 push-in see jets below
15 010101  N/A 99201-063-0620 main jet #62 push-in see jets below
18 111111  N/A (not sold separately) idle jet press-in tube 0.35=0.0138″

Keyster 0605 kit for PC50A has no #1e
for C4A except no 1e, C5A  except   15 1e
for C4B except 2f 1e, C5B except 2f 15 1e
for F4A except 2g 1e, F5A except 2f 15 1e

#5c #5d drain plugs

Zenith 11-HL on 1970’s Spanish Honda PS50

1970 Honda PS50