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Author Topic: CB750 Exhaust Collar for Aftermarket 4-1  (Read 2104 times)

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Offline zeech

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CB750 Exhaust Collar for Aftermarket 4-1
« on: August 22, 2017, 12:44:16 PM »
I got a used 4-1 exhaust and am unsure on the brand, but I need to find some split collars that will work with it. The tube OD where it meets the engine is a touch over 1.5" and I haven't been able to find anything. I tried using the stock CB750 collars with the double lip, but they are too small to fit around it.

Anyone have ideas on where to get some or what this might be?



« Last Edit: August 22, 2017, 12:50:25 PM by zeech »
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Offline flybox1

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Re: CB750 Exhaust Collar for Aftermarket 4-1
« Reply #1 on: August 22, 2017, 12:54:40 PM »
you can contact  MACPerformance.  They can get you what you need.
IIRC, its Manny in the parts dept.  Just needs that OD...
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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

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Offline zeech

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Re: CB750 Exhaust Collar for Aftermarket 4-1
« Reply #2 on: August 22, 2017, 01:09:55 PM »
I called MAC and they said it is not their exhaust unfortunately and they don't have collars that will work.... don't know why but that's what they said... maybe I need to talk to Manny, cause this guy was not helpful.
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Offline calj737

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Re: CB750 Exhaust Collar for Aftermarket 4-1
« Reply #3 on: August 22, 2017, 01:34:13 PM »
If I recall, there will be a small gap with the stock split collars, and that's shouldn't be an issue. The stock flanges align to force the collars into the o-ring for a proper seal. Put together, what's the ID of the stock collars?
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Offline zeech

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Re: CB750 Exhaust Collar for Aftermarket 4-1
« Reply #4 on: August 22, 2017, 01:45:26 PM »
The stock collar diameter is too small and leaves a MAJOR gap between the pipe and collars surfaces. I would have to measure but it's significantly smaller.
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Offline flybox1

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Re: CB750 Exhaust Collar for Aftermarket 4-1
« Reply #5 on: August 22, 2017, 01:45:54 PM »
Quote from: calj737 on August 22, 2017, 01:34:13 PM
If I recall, there will be a small gap with the stock split collars, and that's shouldn't be an issue. The stock flanges align to force the collars into the o-ring for a proper seal. Put together, what's the ID of the stock collars?
^^ Correct. 

Dont tell them you dont have a MAC  ::) ;D  l
They'll sell them to you.  IIRC, mine were about $20 shipped.  fit perfectly.
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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…"

Offline zeech

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Re: CB750 Exhaust Collar for Aftermarket 4-1
« Reply #6 on: August 22, 2017, 07:30:36 PM »
ID on the stock split collars is 1.335"
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Offline zeech

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Re: CB750 Exhaust Collar for Aftermarket 4-1
« Reply #7 on: August 23, 2017, 11:01:03 AM »
Called again and they are sending me some that are 1 5/8 so I'll give those a try.
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Offline calj737

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Re: CB750 Exhaust Collar for Aftermarket 4-1
« Reply #8 on: August 23, 2017, 12:50:35 PM »
Too big. Thats 1.625 for your pipes that measure 1.49. Thats a greater delta than the "too small" ones at 1.335. Can you post a picture of the ones you have slipped on the pipe so we can see the major gap?
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"Of all tyrannies, a tyranny sincerely exercised for the good of it's victim may be the most oppressive. It may be better to live under robber barons than under omnipotent moral busybodies. The robber baron's cruelty may sometimes sleep, his cupidity may at some point be satiated, but those who torment us for our own good will torment us without end for they do so with the approval of their own conscience." - C.S. Lewis

Offline 754

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Re: CB750 Exhaust Collar for Aftermarket 4-1
« Reply #9 on: August 23, 2017, 12:54:52 PM »
 Gap does not not matter much, mainly you want the collars, to push the pipe end against the gasket.
« Last Edit: August 23, 2017, 12:56:44 PM by 754 »
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Offline zeech

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Re: CB750 Exhaust Collar for Aftermarket 4-1
« Reply #10 on: August 23, 2017, 01:00:22 PM »
My pipes are 1.53" so it's not that much bigger and I can trim them down to get the right fit of around 1.5 if I need to. And like 754 says I don't care if there is a gap, I just need them to hold the collars in place and compress the gaskets.
« Last Edit: August 23, 2017, 01:04:23 PM by zeech »
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Offline flybox1

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Re: CB750 Exhaust Collar for Aftermarket 4-1
« Reply #11 on: August 23, 2017, 01:02:33 PM »
Yeah...the ones they send you can be massaged to work.  They are just a spacer, so to speak. . .
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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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