Best option to rebuild PD50Bs

If it's broken or just needs tweaked

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Totaled108
Posts: 65
Joined: Mon Oct 03, 2011 3:45 am

Best option to rebuild PD50Bs

Postby Totaled108 » Wed Jun 13, 2012 5:03 pm

I have tore apart fully the PD50B carbs since they were not getting fully clean enough. I willcontinue searching, but can't seem to find the rare rebuild kits for these boys.

What option should I look into if I'm un able to find any?

Totaled108
Posts: 65
Joined: Mon Oct 03, 2011 3:45 am

Re: Best option to rebuild PD50Bs

Postby Totaled108 » Wed Jun 13, 2012 7:17 pm

Just talked to Honda after some searching because it seems that there are no more kits sold other then by Honda. $50 and change per carb without float valve.

Fuel is the only issue with how this bike runs. I did a general cleaning minus pulling the slow jet (press, yet pulled them during this disassemply) and have the engine idling on 1, 2 and 4, while 3 remained cold. We eliminated air leaks and any spark issues. This is why I chose to have done with it and do a thorough job on the carb.

During the removal of the slow jets, #3's slow jet was very dry, and the other three slow jets had fuel on them. It was covered with crud, even though I could look through the main hole on that jet.

If I go through with this rebuild I want to know it will run for years to come. Or should I try to fit different carbs or with the cost come out in the wash?

I'm getting ready to do a full carb body dunk so there is no passage way clogged before the rebuild.

Totaled108
Posts: 65
Joined: Mon Oct 03, 2011 3:45 am

Re: Best option to rebuild PD50Bs

Postby Totaled108 » Wed Jun 13, 2012 7:18 pm

Also, the accelerator pump is torn so I hope these are around as well.

MiGhost
Posts: 379
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Location: South Central Mitten

Re: Best option to rebuild PD50Bs

Postby MiGhost » Thu Jun 14, 2012 12:30 am

I am getting ready to rebuild a set of PD50B carbs also. Rebuild kits are hard to find in stock anywhere.

I have tracked down the following info for parts interchange. Floats, Float bowl gasket, Needle valve, Mixture screw, and Float bowl drain screw will all interchange with 77-78 CB750A, and 77-78 CB750K carbs. This means that the cheaper more available kits for the 750A, or 750K carbs can be used. with one exception.

The 750A, and 750K carbs do not use a metal cross over tube for the accelerator pump, and fuel delivery curcuit, and do not contain the o-rings in the kit. All other o-rings, and brass pieces are included in the full keyster kits.
NOTE: The jets contained in these kits will most likely not be the correct jets.

Edit:Updated info on the o-rings
cgswss10 wrote:Oh by the way, those o-rings can be replaced by standard "dash" sizes. The fuel rail are "-010" and the acel pump rail take "-007" o-rings. Of course you have to use "fuel proof" o-rings which would normally mean "Nitrile" AKA "Buna-N" o-rings NOT regular neoprene rubber.

viewtopic.php?f=4&t=6013&start=15


Parts available from Sirius Consolidated INC.

HONDA CB650 KEYSTER CARB KIT 1979 KH-1204

HONDA CB750A CB750 AUTOMATIC KEYSTER CARB KIT 1976 - 78 KH-1260

HONDA CROSS OVER TUBE O-RINGS (1.5 x 6.6 & 1.8 x 3.7)
NOTE: I have not positively confirmed that theses are the correct cross over tube o-rings

CB650 CB750 LTD 1979 AIR CUT OFF VALVE

HONDA FLOAT BOWL GASKET (Single)

CB750 CARB FLOAT BOWL GASKETS (Set of 4) 1977 - 1978

HONDA FLOAT BOWL DRAIN SCREW (Single)

HONDA CX500 CB650 CB750 CB900 FLOAT BOWL DRAIN SCREWS (Set of 4)

HONDA CX500 CB750 AIR SCREW NEEDLE O-RINGS PACK of 25

HONDA CB550 CB750 XL80 XL185 CARB SLOW JETS (KHS-49A035)

HONDA CB450 SC CM450 CB750A CB750 ACCEL PUMP
NOTE: The pump rod may have to be trimmed to length on these. The pump diaphram is correct.
NOTE: The fuel pump rod for the CB750A is the correct length, and will directly interchange with the PD50 carbs.

Choke Shaft Seals
The felt seals can be obtained through OldSchoolCarbs.

Part interchange info:

Float Bowl interchange for gaskets

16010-393-305 GASKET SET
CB750A (76-78)
CB750K (77-78)

Carbs #1
16015-KFC-910 CHAMBER SET, FLOAT

CB125S (78-79)
CB550K (77-78)
CB650 (79-80)
CB750A (76-78)
CB750F (77-78)
CB750K (77-78)
CM185T (78-79)
XL100 (77-78)
XL125 (76-78)


#2 Carb w/Accellerator pump
16015-428-771 CHAMBER SET, FLOAT

CB650 A (79-80)
CB650C A (80)
NX250 A (88-90)
XL250R A (82-83)
XL250R AC (83)
XL250S A (80-82)
XL500S A (79-81)
XR250L A (91-96)
XR250L AC (91-96)

16023-393-004 CHAMBER SET B, FLOAT
CB750A A (76-78)
CB750K A (77-78)
Note: These float bowls are identical to the above, but include the accel pump.

#3 & #4 Carb
16015-KN4-A10 CHAMBER SET, FLOAT

CB550K A (77-78)
CB650 A (79-80)
CB650C A (80)
CB750A A (76-78)
CB750F A (77-78)
CB750K A (77-78)
CRF100F A (04-12)
NSF100 A (06)
XL100S A (79-85)
XL350 A (77-78)
XR100 A (81-03)

Float bowl vent "T" joint
16036-438-671 JOINT SET, THREE-WAY

CB650 A (79-80)
CB650C A (80)
CB900F A (81-82)

Float
16013-405-004 FLOAT SET

CB125S A (80-82)
CB550K A (77-78)
CB650 A (79-80)
CB650C A (80)
CB750A A (77-78)
CB750K A (77)
CM200T A (80-82)
XL100 A (77-78)
XL100S A (79-85)
XL100S AC (85)
XL125S A (79-85)
XL125S AC (84-85)
XL185S A (79-82)
XR100 A (81-84)
XR100R A (85)
XR185 A (79)
XR200 A (80-84)
XR200R A (81-83)
XR250R A (81-82)


Float Needle valve
16011-382-004 VALVE SET, FLOAT

CB125S A (78-82)
CB400A A (78)
CB400TI A (78-79)
CB400TII A (78-79)
CB550K A (77-78)
CB650 A (79-80)
CB650C A (80)
CB750A A (76-78)
CB750F A (77-79)
CB750K A (77-79)
CB750L A (79)
CM185T A (78-79)
CM200T A (80-82)
CM400A A (79)
CM400T A (79)
CX500 A (78-79)
CX500C A (79)
CX500D A (79)
XL100 A (77-78)
XL100S A (79-85)
XL100S AC (85)
XL125 A (76-78)
XL125S A (79-85)
XL125S AC (84-85)
XL185S A (79-82)
XL250R A (84-87)
XL250R AC (84-87)
XL250S A (78-81)
XL350 A (77-78)
XL350R A (84-85)
XL350R AC (84-85)
XL500S A (79-81)
XL600R A (83-87)
XL600R AC (84-87)
XR100 A (81-84)


The latest part that replaces this item is:
16011-KCK-910 VALVE SET, FLOAT


16011-KCK-910 VALVE SET, FLOAT (Float needle)
CRF150F A (03-07)
CRF230F A (03-07)
XL125S A (85)
XL125S AC (85)


Pilot Needle Screw
16016-KC2-970 SCREW SET A

CB1000C A (83)
CB1100F A (83)
CB125S A (80-82)
CB125S A (84-85)
CB125S AC (84-85)
CB400T A (80-81)
CB450SC A (82-83)
CB450SC A (85-86)
CB450SC AC (85-86)
CB450T A (82)
CB650 A (80-82)
CB650C A (80-81)
CB650SC A (82)
CB750C A (80-82)
CB750F A (80-82)
CB750K A (80-82)
CB750SC A (82-83)
CB900C A (80-82)
CB900F A (81-82)
CBX A (80-82)
CM200T A (80-82)
CM250C A (82-83)
CM250C AC (83)
CM400A A (80-81)
CM400C A (81)
CM400E A (80-81)
CM400T A (80-81)
CM450A A (82-83)
CM450C A (82)
CM450E A (82-83)
CX500C A (80-82)
CX500D A (80-81)
CX650C A (83)
FT500 A (82-83)
GL1100 A (80-83)
GL1100A A (82-83)
GL1100I A (80-83)
GL500 A (81-82)
GL500I A (81-82)
GL650 A (83)
GL650I A (83)
NX125 A (88-90)
NX125 AC (88-90)
NX250 A (89-90)
NX250 AC (90)
XL100S A (80-84)

Edit: Added carb specs. Thanx for the info usbear.
PD50 Carb Specs CB650 79-80, CB650C 80
PD50A JET, MAIN (#90) SLOW (#35) slide is 56 B (small air cut out) needle - 59 A (high clip position)
PD50B JET, MAIN (#90) SLOW (#35) slide is 81 B (larger air cut out) needle - 35 B ( lower clip position)
PD50D JET, MAIN (#95) SLOW (#35) slide ?? needle ??

Hopefully this helps.

edit: 6/17/12 corrected misinformation on #2 &#3 float chambers :oops:
edit: 7/25/13 added carb specs.
edit: 11/02/13 added choke shaft seal info.

Ghost
Last edited by MiGhost on Sat Nov 02, 2013 2:35 am, edited 6 times in total.
~ Ghost

PD50 Carb Info
82 CB650SC Brake Caliper Info

Stable
Wayward Son:1980 CB650C, RestoMod Period Custom Touring
Bad Moon: 1983 XJ750MK Midnight Maxim, Full Dress Tour Deluxe w/ X-1 Fairing
Nemesis: 1983 XJ750K Maxim, Old School style chopper

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Volker_P
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Location: southern Germany

Re: Best option to rebuild PD50Bs

Postby Volker_P » Thu Jun 14, 2012 6:24 am

Thanks, that's really great info! :D
BTW, accelerator pump is at carb #2. :wink:
Cosky's great (free) online manual: http://cosky0.tripod.com

forum links to common technical issues

Totaled108
Posts: 65
Joined: Mon Oct 03, 2011 3:45 am

Re: Best option to rebuild PD50Bs

Postby Totaled108 » Fri Jun 15, 2012 2:50 am

Great info! I'll try to re-use as many pieces as I can, the air cut offs are in good condition. Accel pump is shot. There is a place around here that specializes in O-rings that I will source from. After cleaning up the carbs thoroughly, no jets need replacing, even the plungers seem to be doing well.

All the carb bodies have been Chem Dipped, and jet sonic cleaned. Looking good. Just have to put everything together and make this thing run right. I have never done this before, I'm excited and worried all at the same time!

MiGhost
Posts: 379
Joined: Tue Jun 07, 2011 2:30 am
Location: South Central Mitten

Re: Best option to rebuild PD50Bs

Postby MiGhost » Sun Jun 17, 2012 3:10 am

Good catch Volker
Information corrected. :oops:

Ghost
~ Ghost

PD50 Carb Info
82 CB650SC Brake Caliper Info

Stable
Wayward Son:1980 CB650C, RestoMod Period Custom Touring
Bad Moon: 1983 XJ750MK Midnight Maxim, Full Dress Tour Deluxe w/ X-1 Fairing
Nemesis: 1983 XJ750K Maxim, Old School style chopper

MiGhost
Posts: 379
Joined: Tue Jun 07, 2011 2:30 am
Location: South Central Mitten

Re: Best option to rebuild PD50Bs

Postby MiGhost » Sun Jun 17, 2012 3:18 am

When you find out the O-ring sizes, Please post them here to complete the information.

Thanx
Ghost
~ Ghost

PD50 Carb Info
82 CB650SC Brake Caliper Info

Stable
Wayward Son:1980 CB650C, RestoMod Period Custom Touring
Bad Moon: 1983 XJ750MK Midnight Maxim, Full Dress Tour Deluxe w/ X-1 Fairing
Nemesis: 1983 XJ750K Maxim, Old School style chopper

cb650
Posts: 2911
Joined: Fri Mar 03, 2006 7:20 am
Location: Denver CO USA
Contact:

Re: Best option to rebuild PD50Bs

Postby cb650 » Sun Jun 17, 2012 2:49 pm

Volker I would suggest a locked thread with this info and the electric interchange list.
Did you clean the tank out?!?!?!?!

Totaled108
Posts: 65
Joined: Mon Oct 03, 2011 3:45 am

Re: Best option to rebuild PD50Bs

Postby Totaled108 » Mon Jun 18, 2012 9:49 pm

That place that I was told had O-rings, didn't have any of the sizes I needed. It was a place that specializes in hydraulic systems.

I was careful in taking all the O-rings off, so I'll be putting them in an oil bath while Isearch a few other places in the hopes that maybe another place may have this size.

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Volker_P
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Location: southern Germany

Re: Best option to rebuild PD50Bs

Postby Volker_P » Tue Jun 19, 2012 2:16 am

cb650 wrote:Volker I would suggest a locked thread with this info and the electric interchange list.

It's already in my internal technical links list.
One may also click on "forum links" in my signature to get there. :wink:
I may still compose something anyway.
Cosky's great (free) online manual: http://cosky0.tripod.com

forum links to common technical issues

Totaled108
Posts: 65
Joined: Mon Oct 03, 2011 3:45 am

Re: Best option to rebuild PD50Bs

Postby Totaled108 » Thu Jun 21, 2012 5:58 pm

Brief update. The accelerator pump passage ways were VERY clogged and had to run them through the sonic 'jewelery' cleaner again, now they flow freely.

Still unable to get O-ring sizes pin pointed, but have started assembling the carbs since the O-rings seem supple and able to seal. After these are fully assembled and the bike is running, I'll take the other set of PD50B carbs apart and get the O-ring sizes and post them.

Thanks for all the info.

Totaled108
Posts: 65
Joined: Mon Oct 03, 2011 3:45 am

Re: Best option to rebuild PD50Bs

Postby Totaled108 » Sat Jun 23, 2012 10:36 pm

While I will be doing another PD50B rebuild soon, the one that I did rebuild, I reused all but one O-ring.

Is ALIVE!!!!!!!!!!! I hooked it up today and had a fun time getting it all back together. With just a bench synch, premium fuel and a little hope it runs great. Took a second to come to life, but have taken it for a few miles around town. It pulls hard and smooth to 8,000 rpms, I just don't care to take it pass that. Also I'm looking at the road and smiling, so I have no Idea if I'm revving higher. I'm so glad I did a full carb rebuild!

After warming it up, hooked the synch tool up and found it was right on the money, no wonder it pulls so well. :)

We adjusted the valves, but it's still noisy. Fresh oil too. Do these engines have a sewing machine sound near idle?

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Volker_P
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Location: southern Germany

Re: Best option to rebuild PD50Bs

Postby Volker_P » Sun Jun 24, 2012 6:24 am

Congratulations! :D

Sewing machine at idle typically means valves too loose.

One may use a screwdriver as a stethoscope on the four rocker cams to get an idea if this is valve noise and to locate it at least to one out of two.
Of course it has to be cold for adjustment later.

If this seems all right, you may remove the center valve cover and verify cam chain tension directly at the chain with a screwdriver.
Sometimes it requires several efforts to get good tension, sometimes it gets even worse. Just don't give up until you can verify tension at the sprocket.

Depending on mileage, old engines are certainly noisier.
Cosky's great (free) online manual: http://cosky0.tripod.com

forum links to common technical issues

Totaled108
Posts: 65
Joined: Mon Oct 03, 2011 3:45 am

Re: Best option to rebuild PD50Bs

Postby Totaled108 » Sun Jun 24, 2012 9:19 am

Right on. I'll be doing some fine tuning today, including the timing chain.
We did do the valve adjustment with a cold engine.
The Odometer reads 47,xxx miles, is that 'higher' mileage for these motors?


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