Author Topic: Exhaust swap and they have different mounting systems...help!  (Read 2613 times)

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Offline brycegp

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Exhaust swap and they have different mounting systems...help!
« on: August 17, 2009, 05:37:51 PM »
Ok...I'm a newb building a '71 CB750K and will be starting my build thread very soon.  But I have done research on this problem but haven't been able to find an exact answer. 

I am swapping my exhaust.  Currently, it seems there was a cb750F header on that I just pullled off today.  And I had bought a 71 CB750 4 into 2 system to swap out.  But they mount differently.

Below are 3 pics.  First is the cb750F exhaust I just took off with the "lip" at the mounting point.  Second is the clamp that was used to mount the cb750F exhaust.  And third is the new exhaust headers that I am trying to put on.

So my question is what do I have to do?  What mods need done or what mounting clamps do I need in order to mount these new headers?
1971 CB750K/F - El Toro
El Toro Build Thread - http://forums.sohc4.net/index.php?topic=73552.0

Offline Old Scrambler

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Re: Exhaust swap and they have different mounting systems...help!
« Reply #1 on: August 17, 2009, 05:44:48 PM »
You will need the chrome-plated spigots and screws to mount to the head with new copper gaskets.  Then you will need a set of 4 clamps to hold the header pipes to the spigots.  Take a look at the parts book or shop manual for the K0-K4 motors...........
Dennis in Wisconsin
'64 Triumph Cub & '74 Honda CB750 Bonneville Salt Flats AMA Record Holder (6)
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Offline brycegp

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1971 CB750K/F - El Toro
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Offline Old Scrambler

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Re: Exhaust swap and they have different mounting systems...help!
« Reply #3 on: August 17, 2009, 06:11:43 PM »
I can't open easily because of a slow connection to the web..........the screws are the same thread as the studs but have flat topped philips heads in chrome.  Be sure to check the spigots for pealing chrome.  The clamps can usually be cleaned up with a soda wash.  Re-chromed clamps cost as much or more than new.  They are available from you HONDA dealer....plus the bolts.
Dennis in Wisconsin
'64 Triumph Cub & '74 Honda CB750 Bonneville Salt Flats AMA Record Holder (6)
CB750 Classic Bonneville Racer thread - http://forums.sohc4.net/index.php/topic,135473.0.html
'63 CL72 Project(s)
'66 CL77 Red
'67 Triumph T100C
'73 750K3 Owned since New
'77 750F2 Cafe Project
2020 ROYAL ENFIELD Himalayan

Offline Toxic

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Re: Exhaust swap and they have different mounting systems...help!
« Reply #4 on: August 17, 2009, 06:13:11 PM »
That's what you need, now don't forget the copper sealing gaskets.

Make sure you remove 4 used ones from the head.  You wouldn't be the first guy to leave one in there and end up stacking a second one on top of it.  Resulting in a poor fit.

Tip:
After you properly clean out the seating area in the head use a little dab of grease on the gasket to hold them in place while you position the header.

Offline brycegp

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Re: Exhaust swap and they have different mounting systems...help!
« Reply #5 on: August 18, 2009, 09:08:05 AM »
Well...if anyone has 4 spigots and 4 clamps available, I officially in the market.

And as far as getting the studs out...any tips in the easiest way to go about it?
1971 CB750K/F - El Toro
El Toro Build Thread - http://forums.sohc4.net/index.php?topic=73552.0

Offline ekpent

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Re: Exhaust swap and they have different mounting systems...help!
« Reply #6 on: August 18, 2009, 10:18:47 AM »
Start soaking those studs now with some PB Blaster or such now. Longer it sits the better. Guys will chime in but will probably say to use good heat,good vise grips,a hammer to whack them and be careful not to break them.

Offline brycegp

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Re: Exhaust swap and they have different mounting systems...help!
« Reply #7 on: August 18, 2009, 01:15:41 PM »
EKPENT:  the motor is still on the bike.  how would I soak them if that's the case?

on guy told me to put two nuts on it going opposite directions and back them out that way...
1971 CB750K/F - El Toro
El Toro Build Thread - http://forums.sohc4.net/index.php?topic=73552.0

Offline Toxic

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Re: Exhaust swap and they have different mounting systems...help!
« Reply #8 on: August 18, 2009, 01:23:29 PM »
Start soaking those studs now with some PB Blaster or such now. Longer it sits the better. Guys will chime in but will probably say to use good heat,good vise grips,a hammer to whack them and be careful not to break them.

+1 apply a whack directly to the end of the stud and then a sharp whack with the vise grips tightly clamped on.

Once you get it moving then I would use the double nuts to finish the job.

best of luck

Offline Old Scrambler

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Re: Exhaust swap and they have different mounting systems...help!
« Reply #9 on: August 18, 2009, 07:20:19 PM »
The double-nut system works well.  Yes, with the nuts both in place and the outer flush with the end of the stud, a good whack with a hammer will help to loosen things up.......especially if they have been sitting a long time. 

The clamp-collars come in pairs.......2-left & 2-right.  If you want them somewhat ruff but intact, I have a few at $5 each plus shipping but no bolts. I would have to check to see if I have correct pairs. New units are $25 each or more plus bolts. Check with your local dealer. 

 
Dennis in Wisconsin
'64 Triumph Cub & '74 Honda CB750 Bonneville Salt Flats AMA Record Holder (6)
CB750 Classic Bonneville Racer thread - http://forums.sohc4.net/index.php/topic,135473.0.html
'63 CL72 Project(s)
'66 CL77 Red
'67 Triumph T100C
'73 750K3 Owned since New
'77 750F2 Cafe Project
2020 ROYAL ENFIELD Himalayan

Offline brycegp

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Re: Exhaust swap and they have different mounting systems...help!
« Reply #10 on: August 20, 2009, 03:48:57 PM »
VISE GRIPS...sweet taste of success!!
1971 CB750K/F - El Toro
El Toro Build Thread - http://forums.sohc4.net/index.php?topic=73552.0

Offline MJL

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Re: Exhaust swap and they have different mounting systems...help!
« Reply #11 on: August 20, 2009, 04:07:41 PM »
Well...if anyone has 4 spigots and 4 clamps available, I officially in the market.

And as far as getting the studs out...any tips in the easiest way to go about it?
Cycle X has them.

http://www.cyclexchange.net/Exhaust%20System%20Page.htm

Scroll down almost all the way to the bottom.
No matter how fast or how far I rode, I couldn't leave her memory behind.