Author Topic: Can float valve seats be replaced on PD Keihin carbs?  (Read 1034 times)

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Offline scotty

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Can float valve seats be replaced on PD Keihin carbs?
« on: January 13, 2014, 10:12:26 PM »
I screwed one of mine up, trying to clean it.  It will not stop leaking.   Can they be replaced?


Offline mrbreeze

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Re: Can float valve seats be replaced on PD Keihin carbs?
« Reply #1 on: January 13, 2014, 10:34:09 PM »
You can get a needle & seat alone or get it in a carb kit. Carb kit is the better deal.
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Offline scotty

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Re: Can float valve seats be replaced on PD Keihin carbs?
« Reply #2 on: January 13, 2014, 10:46:40 PM »
Cool.  Where is a god place to buy, and how do you get them out?  They don't unscrew

Offline mrbreeze

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Re: Can float valve seats be replaced on PD Keihin carbs?
« Reply #3 on: January 13, 2014, 11:00:50 PM »
I don't know of any carby that doesn't have a replacable float seat. What bike are we working on?
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Offline scotty

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Re: Can float valve seats be replaced on PD Keihin carbs?
« Reply #4 on: January 14, 2014, 12:00:36 AM »
It's a 77' CB550, but the carbs are from a 78'.   They are the PD Keihin.    How do you remove them? 

Offline 750K

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Re: Can float valve seats be replaced on PD Keihin carbs?
« Reply #5 on: January 14, 2014, 12:43:05 AM »
If the seats are like the pd's on the 750's they don't come out, the brass seats are pressed in. How bad did you damage it, I've read of guys using valve lapping paste to re lap the seat if its worn but usually replacing the rubber float tipped needle does the trick. Although sounds like you're dealing with something worse.
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Offline mrbreeze

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Re: Can float valve seats be replaced on PD Keihin carbs?
« Reply #6 on: January 14, 2014, 01:04:01 AM »
I'm not familiar with 550's or anything over 1976. 76' & before have screw ins.
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Offline scotty

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Re: Can float valve seats be replaced on PD Keihin carbs?
« Reply #7 on: January 14, 2014, 10:20:51 AM »
I looks to me like they don't come out, but I have no experience with them.  I got new needles and it wouldn't stop leaking.  Then I tried to clean it with steel wool and it seems to be leaking worse now.  What would you use to lap them them? 

Offline flybox1

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Offline scotty

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Re: Can float valve seats be replaced on PD Keihin carbs?
« Reply #9 on: January 14, 2014, 10:43:24 AM »
Great!  So, how to remove?  Just pull it out like a Tijuana dentist?

Offline flybox1

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Re: Can float valve seats be replaced on PD Keihin carbs?
« Reply #10 on: January 14, 2014, 10:55:19 AM »
just to prevent damage to the seat itself....Id add a little PB blaster around its edge, and let it sit for a bit.
wipe off the excess and then hit it with a heat gun.
should pull straight out.....
'78 750K (F3 engine) PD42b's -  modded stock airbox w/K&N  filter, #42/#120jets, 1 needle shim, Fuel screws @ 1 turn out. Wrapped 4-1 Kerker. ConeEngeering Quiet core slip on
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Offline scotty

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Re: Can float valve seats be replaced on PD Keihin carbs?
« Reply #11 on: January 14, 2014, 01:59:14 PM »
Thanks!  I'll give it a shot

Online bwaller

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Re: Can float valve seats be replaced on PD Keihin carbs?
« Reply #12 on: January 14, 2014, 04:21:40 PM »
I've used lapping compound on the end of a Q-tip to save them.

Offline harisuluv

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Re: Can float valve seats be replaced on PD Keihin carbs?
« Reply #13 on: January 14, 2014, 04:45:37 PM »
http://4into1.com/float-needle-valve-assembly-for-keihin-carbs-cb350-cb400-cb500-cb550/

Is this the right link?  It's to non PD style carbs, push in with o-ring.  The PD carbs have a pressed in seat as mentioned.
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Offline scotty

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Re: Can float valve seats be replaced on PD Keihin carbs?
« Reply #14 on: January 15, 2014, 06:47:12 PM »
I don't know if that is the right part.  I guess I'll have to remove them and have a look.  I haven't been able to find the PD style seats.   Maybe it's time to get the older style carbs.

Offline Bankerdanny

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Re: Can float valve seats be replaced on PD Keihin carbs?
« Reply #15 on: January 15, 2014, 06:51:53 PM »
All the needle seats are press fit. It comes out, it's just work. but since you are replacing the seat anyway you don't need to worry about damaging the old one.
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Offline harisuluv

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Re: Can float valve seats be replaced on PD Keihin carbs?
« Reply #16 on: January 15, 2014, 10:52:21 PM »
Banker I think you're talking about the older style carbs.  They are also "press fit" in that they have an o ring and you press them in and then they are held by a clip.

I think this guy is getting confused, his first assertion that his PD carb does not have a removable seat.  More importantly, there are no "replacement" seats for this style to my knowledge. 

You mentioned getting a different set, whatever variety that may be, however, you can just get a replacement body of the exact same type.
Check out my carb rebuild thread! http://forums.sohc4.net/index.php?topic=105640.0

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Offline tomkimberly

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Re: Can float valve seats be replaced on PD Keihin carbs?
« Reply #17 on: January 16, 2014, 06:42:58 PM »
The easy way polish the seat is to get some of those cotton swabs with wooden sticks. Trim to about 4 inches or so, install into a drill, dip the swab in some metal polish, insert into seat and let her spin. Do it 3-4 times.

Tom


Offline scotty

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Re: Can float valve seats be replaced on PD Keihin carbs?
« Reply #18 on: January 22, 2014, 01:25:39 AM »
It turns out there are no replacement seats for these carbs.  They are not meant to be removed.  It's the ones with the rubber tipped needles. 

I think the seat is not round anymore, and won't seal.  I have tried cleaning them and it didn't help.  I think I need to lap them smooth again, with something like the shape of a pencil, but metal.  Any ideas?

Offline flybox1

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Re: Can float valve seats be replaced on PD Keihin carbs?
« Reply #19 on: January 22, 2014, 07:20:46 AM »
New rubber tipped float valves should have cured the leak.
Tell us exactly how you checked that it still leaked.


If you put the carbs back on the bike and just turned on the fuel, you've got something else going on, like a stuck float or improperly set float heights.

If you took your bowls off one by one and tested your finger against the float valve to shut off fuel, with new rubber tipped float valves as you say, I bet you would have seen the fuel flow stop.

It's pretty difficult for rubber to wear brass out of round. Especially with the retainer wire around the tang preventing the float valve from spinning.
« Last Edit: January 22, 2014, 07:23:41 AM by flybox1 »
'78 750K (F3 engine) PD42b's -  modded stock airbox w/K&N  filter, #42/#120jets, 1 needle shim, Fuel screws @ 1 turn out. Wrapped 4-1 Kerker. ConeEngeering Quiet core slip on
Past Bikes
1973 CB350Four, 1983 Yamaha XS400K
77/78 cool 2 member #3
"Knowledge without mileage equals bullsh!t" - Henry Rollins

"This is my CB. There are many like it, but this one is mine…"

Offline lucky

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Re: Can float valve seats be replaced on PD Keihin carbs?
« Reply #20 on: January 22, 2014, 07:22:05 AM »
I looks to me like they don't come out, but I have no experience with them.  I got new needles and it wouldn't stop leaking.  Then I tried to clean it with steel wool and it seems to be leaking worse now.  What would you use to lap them them?

Just to cover the bases....
The metal float needles are NOT interchangeable with the rubber tipped float needles.
« Last Edit: January 22, 2014, 07:27:43 AM by lucky »

Offline harisuluv

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Re: Can float valve seats be replaced on PD Keihin carbs?
« Reply #21 on: January 22, 2014, 08:50:43 AM »
I got a great idea: How about a picture of this "damaged" seat or what you're talking about.
Check out my carb rebuild thread! http://forums.sohc4.net/index.php?topic=105640.0

Need carburetor parts?  http://forums.sohc4.net/index.php?topic=115539.0

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Offline scotty

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Re: Can float valve seats be replaced on PD Keihin carbs?
« Reply #22 on: January 22, 2014, 04:38:28 PM »
I don't think I can take a pic that small.  These float needles are pretty new, and it started leaking after it sat for a few weeks.  I screwed up and tried to clean it out with the wrong object, and now it leaks worse.  I got a new needle today and tried it, it didn't help.  I adjusted the float all the way up, and that didn't help.   I wouldn't have #$%*ed around with the seat, except I thought I could replace them if need be.  Not the case.  I does close the flow if you hold it up with finger pressure , but not by using the float.

Offline flybox1

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Re: Can float valve seats be replaced on PD Keihin carbs?
« Reply #23 on: January 22, 2014, 04:44:20 PM »
If it closes with your finger, it will likely close with the float.
Tell us about your float setting procedure and the float height you used.
'78 750K (F3 engine) PD42b's -  modded stock airbox w/K&N  filter, #42/#120jets, 1 needle shim, Fuel screws @ 1 turn out. Wrapped 4-1 Kerker. ConeEngeering Quiet core slip on
Past Bikes
1973 CB350Four, 1983 Yamaha XS400K
77/78 cool 2 member #3
"Knowledge without mileage equals bullsh!t" - Henry Rollins

"This is my CB. There are many like it, but this one is mine…"

 

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