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Author Topic: CB 650 inlet manifolds  (Read 1171 times)

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Offline themanxman

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CB 650 inlet manifolds
« on: May 22, 2016, 01:17:54 AM »
Good morning all you lovely people.
 I`m looking to replace the inlet manifold rubbers on a 1979 CB650 with the Khein PD51a carbs. All the ones I`ve found seem to be for the later CV type (won`t fit). The manifold stub is 38mm and the carb side is 35mm. Anybody know if these are available ?
I was wondering if the CB550 or 750 ones are the same ? (unlikely I know)
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Offline DaveBarbier

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CB 650 inlet manifolds
« Reply #1 on: May 22, 2016, 04:59:58 AM »
I don't know which carbs those are but I do know that the '79 650 can accept 750 carbs. I had a hard time finding carbs for my '82 650 as the spacing is different.

So, since the carbs fit, I assume the insulators would fit also.

Insulators from the 550 would be too small, I believe.

You might want to do a search for "Paulages 550 650 hybrid". He puts a 650 top end on a 550 with modifications and uses 750 carbs. He might mention which insulators he got.

Edit: So I just realized that the PD carbs you mention are the stock ones for that 650, right? So you're just looking to replace the factory insulators? Have you tried looking at the parts diagram at either Partzilla or CMSNL?
« Last Edit: May 22, 2016, 05:02:33 AM by DaveBarbier »
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Offline themanxman

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Re: CB 650 inlet manifolds
« Reply #2 on: May 22, 2016, 10:11:10 AM »
Thanks for that. Those suppliers are new to me, I will have a look. Yes they are the stock carbs. If the 750 ones go on then it`s happy days, as they are quite plentiful and not to dear.
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Offline themanxman

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Re: CB 650 inlet manifolds
« Reply #3 on: May 22, 2016, 11:31:38 AM »
The rubbers for the 750 may be the same sizes but they are splayed so no luck there, Partzilla lists them as discontinued but CMSNL have them! 17 euros each not to bad. Good bye to grumbly, lumpy carbs, hopefully.
Thanks again.
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Offline SOHC4 Cafe Racer Fan

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Re: CB 650 inlet manifolds
« Reply #4 on: May 23, 2016, 10:42:12 AM »
Quote from: themanxman on May 22, 2016, 11:31:38 AM
The rubbers for the 750 may be the same sizes but they are splayed so no luck there, Partzilla lists them as discontinued but CMSNL have them! 17 euros each not to bad. Good bye to grumbly, lumpy carbs, hopefully.
Thanks again.

I think you are correct -- that the spacing at the intake side of the head is different than a 750K, so you would likely need the 1979-1989 CB650 manifolds, even if they do end up reaching out to the same spacing as the 750 carburetors.
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Offline cb650

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Re: CB 650 inlet manifolds
« Reply #5 on: May 23, 2016, 11:37:38 AM »
79/80 are the only ones that will work.    750 wont.  Dont know about the 550 ones.
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Offline jonda500

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Re: CB 650 inlet manifolds
« Reply #6 on: May 24, 2016, 09:03:55 PM »
Don't know if this helps, but I found 750 carbs fit on a 500 by using 77/78 550 intake boots reversed (smaller 34mm side to engine, larger 36mm side to carbs) and 77/78 intake manifolds...
John

below are pics or it didn't happen right?
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Offline themanxman

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Re: CB 650 inlet manifolds
« Reply #7 on: May 25, 2016, 05:11:13 AM »
Well I have some on order now from Germany which claim to be for a 79-81 650. This is still a bit of a gamble as Honda seemed to have changed over to CV carbs by 81. Lets see....
I do have a rack of CV carbs from a later bike which I broke for parts, but the spacing between them is different.
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Offline onepieceatatime

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Re: CB 650 inlet manifolds
« Reply #8 on: May 25, 2016, 08:08:47 AM »
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1965 CA77
1972 CB750K Ol' Sarge
1974 CB450K7
1977 CB750K7
1977 CB750K7
1980 CB650C
1982 CM450A
1997 GL1500SE
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