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Author Topic: Carb Sync stumper -- 1976 CB550  (Read 2672 times)

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Offline carnivorous chicken

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Carb Sync stumper -- 1976 CB550
« on: August 16, 2015, 09:16:53 AM »
Hi All, working on a friend's bike over the weekend, 1976 CB550. I brought my sync tool for the carbs, but found out that the manifolds between the carb and the engine do not have the ports to plug in the sync tool. Nothing on the rubber boots either -- although his bike has some customization such as pods and it looked like the boots between the carb and intake and between the carb and filters may have been new/aftermarket. They appear to be correct 1976 carbs -- stamped with 087A. Did I miss something?

He bench synced the carbs and the bike runs well, especially after valves, points and timing. But I'm curious about the sync problem. Thanks in advance.
« Last Edit: August 16, 2015, 09:37:16 AM by carnivorous chicken »
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Offline carnivorous chicken

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Re: Carb Sync stumper -- 1976 CB550
« Reply #1 on: August 16, 2015, 09:33:16 AM »
Quick follow up: Part # search shows that the manifolds for 1975 and 1976 K models are the same part. Are these manifolds off a later bike?
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Offline carnivorous chicken

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Re: Carb Sync stumper -- 1976 CB550
« Reply #2 on: August 16, 2015, 09:37:48 AM »
Quote from: carnivorous chicken on August 16, 2015, 09:33:16 AM
Quick follow up: Part # search shows that the manifolds for 1975 and 1976 K models are the same part. Are these manifolds off a later bike? 1977 and 1978 CB550 manifolds are different part #s and do not show the sync tool inputs.
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Offline RevDoc

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Re: Carb Sync stumper -- 1976 CB550
« Reply #3 on: August 16, 2015, 09:58:41 AM »
Quote from: carnivorous chicken on August 16, 2015, 09:37:48 AM
Quote from: carnivorous chicken on August 16, 2015, 09:33:16 AM
Quick follow up: Part # search shows that the manifolds for 1975 and 1976 K models are the same part. Are these manifolds off a later bike? 1977 and 1978 CB550 manifolds are different part #s and do not show the sync tool inputs.

My '78 550 has stock PD46C carbs & inlet runners. There are vacuum synch ports.
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Dana

'78 CB550K--Angie
'82 CB750 Custom--Eva



As soon as you straddle a bike expect every other driver on the road to suddenly start competeing for the title "Dumbestsonofa#$%*inallNorthAmerica!!"

Offline carnivorous chicken

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Re: Carb Sync stumper -- 1976 CB550
« Reply #4 on: August 16, 2015, 10:00:20 AM »
Quote from: RevDoc on August 16, 2015, 09:58:41 AM
Quote from: carnivorous chicken on August 16, 2015, 09:37:48 AM
Quote from: carnivorous chicken on August 16, 2015, 09:33:16 AM
Quick follow up: Part # search shows that the manifolds for 1975 and 1976 K models are the same part. Are these manifolds off a later bike? 1977 and 1978 CB550 manifolds are different part #s and do not show the sync tool inputs.

My '78 550 has stock PD46C carbs & inlet runners. There are vacuum synch ports.

Ahh... interesting. Thanks for the response. Anyone else, ideas as to why my friend's would have no sync ports?
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Offline mrfish2

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Re: Carb Sync stumper -- 1976 CB550
« Reply #5 on: August 16, 2015, 07:26:55 PM »
Are you saying he doesn't have the screws on the inlets, circled here in red?

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1976 CB550K            1979 XS1100
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Offline jonda500

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Re: Carb Sync stumper -- 1976 CB550
« Reply #6 on: August 17, 2015, 05:50:53 AM »
I have a set of 78 cb550 inlet manifolds with no vacuum sync ports - I thought the PD carbs had the vacuum ports in them?
John
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Remember that an ignoramus is only someone who doesn't know something you just learned yesterday!

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Offline carnivorous chicken

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Re: Carb Sync stumper -- 1976 CB550
« Reply #7 on: August 17, 2015, 07:59:52 AM »
Quote from: mrfish2 on August 16, 2015, 07:26:55 PM
Are you saying he doesn't have the screws on the inlets, circled here in red?



That is correct.
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Offline carnivorous chicken

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Re: Carb Sync stumper -- 1976 CB550
« Reply #8 on: August 17, 2015, 08:05:47 AM »
Quote from: jonda500 on August 17, 2015, 05:50:53 AM
I have a set of 78 cb550 inlet manifolds with no vacuum sync ports - I thought the PD carbs had the vacuum ports in them?
John

Right. I'm thinking these might be later manifolds on a 1976 bike.
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Offline flybox1

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Re: Carb Sync stumper -- 1976 CB550
« Reply #9 on: August 17, 2015, 08:14:40 AM »
he'll either need a set of PD carbs, or a set of different manifolds.
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'78 750K (F3 engine) PD42b's, Modified airbox w/K&N  filter, 40/110 jets, 1 needle shim, IMS@ 1 turn out. Kerker + Cone 18" QuietCore

Past Bikes
1974 550K0 (stock), 1973 CB350F (stock), 1983 Yamaha XS400K (POS)
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"Knowledge without mileage equals bullsh!t" - Henry Rollins

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Offline carnivorous chicken

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Re: Carb Sync stumper -- 1976 CB550
« Reply #10 on: August 17, 2015, 08:24:14 AM »
Quote from: flybox1 on August 17, 2015, 08:14:40 AM
he'll either need a set of PD carbs, or a set of different manifolds.

Well... yeah.

He's ordered earlier manifolds with the sync inputs. Guessing that there won't be a fitment issue, but will post again if there is.
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Offline streak09

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Re: Carb Sync stumper -- 1976 CB550
« Reply #11 on: August 17, 2015, 09:48:59 AM »
You could always drill and tap the ones he has to make them work like what Mrfish has pointed out...
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Offline carnivorous chicken

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Re: Carb Sync stumper -- 1976 CB550
« Reply #12 on: August 17, 2015, 09:56:12 AM »
I mentioned that as a possibility. I've done it for other bikes (CB160). But he got a set of manifolds with the ports for $15 shipped so that made it a bit of an easier decision!

Thanks all for you responses! Much appreciated.
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Offline flybox1

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Re: Carb Sync stumper -- 1976 CB550
« Reply #13 on: August 17, 2015, 10:02:19 AM »
Quote from: carnivorous chicken on August 17, 2015, 09:56:12 AM
he got a set of manifolds with the ports for $15 shipped so that made it a bit of an easier decision!

Deal of the Day right there!  8)
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'78 750K (F3 engine) PD42b's, Modified airbox w/K&N  filter, 40/110 jets, 1 needle shim, IMS@ 1 turn out. Kerker + Cone 18" QuietCore

Past Bikes
1974 550K0 (stock), 1973 CB350F (stock), 1983 Yamaha XS400K (POS)
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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