Author Topic: I HATE to give up . . . but . . . UNCLE!  (Read 3055 times)

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Offline theofam

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I HATE to give up . . . but . . . UNCLE!
« on: March 03, 2012, 05:49:02 PM »
I'm really struggling with what should be an easy part of my build. . . the exhaust install.

I just unboxed a 4-2 Mac for my 1978 750.  I can't get the joints to tighten against the Mac exhaust.  Here's how I've installed it on the 1-2 exhaust ports, but the pipes were still just hanging there (to the point I could simply pull them off the bike) after tightening the joints against the collars against the gaskets against the head:



What am I missing?  I presume this is how you install the parts:



I can't grasp how the joint measuring over 45mm ID:



Can tighten/seal the exhaust pipe measuring 42mm OD:



I'm frustrated.  Help, before I kick my dog!


Offline mrrch

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Re: I HATE to give up . . . but . . . UNCLE!
« Reply #1 on: March 03, 2012, 06:24:42 PM »
Show a picture with all components on one pipe. If your pipe flange is between your copper gasket and split collar I think you are correct.
my build

1977 CB750K WITH 1976 CB750F ENGINE

Offline theofam

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Re: I HATE to give up . . . but . . . UNCLE!
« Reply #2 on: March 03, 2012, 07:19:37 PM »
I think I got it figured out thanks to this thread's scan of a Jardine exhaust's installation instructions:

http://forums.sohc4.net/index.php?topic=97959.0

I didn't realize the provided collars needed to be spread open:



To fit ON the pipe itself:



Thanks for weighing in, mrrch!

Offline Roach Carver

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Re: I HATE to give up . . . but . . . UNCLE!
« Reply #3 on: March 03, 2012, 07:49:37 PM »
The ones ive used are actuall two separate pieces. Dont know if it matters.

Offline theofam

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Re: I HATE to give up . . . but . . . UNCLE!
« Reply #4 on: March 03, 2012, 08:22:41 PM »
The two separate pieces are stock.  The Mac exhaust comes with the split collars I took a pic of above.  I imagine you can use either type.

Offline octagon

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Re: I HATE to give up . . . but . . . UNCLE!
« Reply #5 on: March 03, 2012, 09:19:22 PM »
you've got it - the flange carries the lip of the actual pipe against the copper crush ring. it's pushed in place by the heavy cast collars. when you torque the collars down, that makes the seal.
the stock honda flanges are split. i think with mac exhaust, a stock flange is too thick, because the mac exhaust tubing is a little wider diameter than stock honda tubing. looks that way in the pictures.
i'm sure this is true of rc engineering headers. i used stock split flanges to install a set of rc headers, but had to carefully widen them first, then grind them to fit the space between the head casting and the exhaust tubing. worked fine in the end but took some time.   

Offline Damfino

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Re: I HATE to give up . . . but . . . UNCLE!
« Reply #6 on: March 04, 2012, 03:24:02 AM »


How's the dog?... :D
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Offline hesselfuzz

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Re: I HATE to give up . . . but . . . UNCLE!
« Reply #7 on: March 04, 2012, 06:53:15 AM »
I think the split collar get flipped over the other way from what you have shown. The flanged end pushes against the flanged end of the exhaust pipe as the big cast finned piece is bolted in place and because of the taper everything wedges tight and seals.
Good luck
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Offline chickenman_26

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Re: I HATE to give up . . . but . . . UNCLE!
« Reply #8 on: March 04, 2012, 07:22:38 AM »
I think the split collar get flipped over the other way from what you have shown.
Nope. He's got it correct.

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Offline toytuff

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Re: I HATE to give up . . . but . . . UNCLE!
« Reply #9 on: March 04, 2012, 07:35:15 AM »


How's the dog?... :D

Yeah! Is the dog alright?

Priorities you know.

tt