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Author Topic: Kerker fit up - HELP!  (Read 2563 times)

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Offline ev0lve

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Kerker fit up - HELP!
« on: February 21, 2009, 12:41:30 PM »
Hi there,

Picked up a used Kerker off of eBay for cheap. Here's the auction
http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=200290267038&sspagename=STRK%3AMEWNX%3AIT&viewitem=#ht_500wt_989

The seller says
FITS 1969-1978 HONDA CB750

which I'm thinking has to be a K cause there are no F's in 69.

Today I get the thing cleaned up and the headers wrapped and sprayed. Go to fit it up and can't make it work.

So the question is: A Kerker for a K should fit up without having to torque the pipes into place? Am I doing this wrong? Every other bike I've had with an aftermarket pipe was golden as soon as you got it into the right place (which might mean having the collector supported with you foot but if you got the flanges over the studs you were golden).

If not, did this #$%* sell me a pipe for an F model or DOHC? The only marking I can find is on the bracket to hang it from the shock. It says D.

So pissed off right now.

Any help very appreciated.
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Offline TheHun

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Re: Kerker fit up - HELP!
« Reply #1 on: February 21, 2009, 01:23:02 PM »
did you get new studs? maybe you got shorter one?
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1978 Honda CB750-K

CBR F3 Coils
Kerker 4.1 Header w/ turn down
Maxi-Dwell Ignition
Foam Air Filter Pods
Superbike bars
Starter Delete

CARB CLEANING/REBUILD: http://www.wix.com/TheHun/CarbCleaning-Site

Not Running to Running, doing the work yourself= Priceless

Offline Bodi

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Re: Kerker fit up - HELP!
« Reply #2 on: February 21, 2009, 01:27:47 PM »
The kerker (or any 4-1 set really) headers I've put on all needed a fair bit of persuasion to go into place. The only time I've had them slip right on like they actually fit correctly is after taking them off for repainting or engine work... I suppose they get relaxed into the "right" shape after being bolted there and heated/cooled a lot of times.
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Offline 75750SS

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Re: Kerker fit up - HELP!
« Reply #3 on: February 21, 2009, 01:46:11 PM »
+1 for Bodi.  I had to spread the pipes a bit to make them fit my 750F.
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Offline 75750SS

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Re: Kerker fit up - HELP!
« Reply #4 on: February 21, 2009, 01:50:59 PM »
and now after looking at your pictures, I used the new bolts that came with the header.  They're probably longer then the stock studs.
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Offline scondon

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Re: Kerker fit up - HELP!
« Reply #5 on: February 21, 2009, 02:42:53 PM »
That appears to be the correct pipe. There is just one type and it fits both F and K models, DOHC Kerkers have a different spread and the muffler is not the same.

  As Bodi points out, it may take a bit of persuasion. Trying to seat all four pipes at once will most likely not work. I generally start with #4, since I'm on that side anyway supporting the muffler. Wiggle it around a bit while pressing in against the head until it slips in all the way, then move down the line.

    Stock studs should work fine, providing they're installed the right way 'round. Just over 3/4" of thread on the end at the pipe.
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Give me..a frame to build a bike on, and my imagination will build upon that frame

KingCustomCycles.com

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Re: Kerker fit up - HELP!
« Reply #6 on: February 21, 2009, 02:45:32 PM »
I believe DOHC and SOHC are interchangeable regarding header pipe dimensions???
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Offline Alan F.

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Re: Kerker fit up - HELP!
« Reply #7 on: February 21, 2009, 02:53:22 PM »
Is it possible that a PO doubled up on the copper exhaust gaskets?  That would make your studs seem a bit short.
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Offline ev0lve

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Re: Kerker fit up - HELP!
« Reply #8 on: February 21, 2009, 02:57:41 PM »
Quote
Stock studs should work fine, providing they're installed the right way 'round. Just over 3/4" of thread on the end at the pipe.

ARG! I assumed (really, really, really have to stop it) that since the exhaust was cantilevered off the studs that I should put the long end into the head. So I did. I'll see if I can back them out of there and turn them around. They're brand new 78 model studs. Thanks for that tip.

Good to hear the fit is nasty business. I was ready to have hurt feelings about this but if it's just a chore then I'll adjust my attitude and continue.

Thanks for all the replies. It's a huge help.

« Last Edit: February 21, 2009, 03:01:40 PM by Iggy »
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Offline ev0lve

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Re: Kerker fit up - HELP!
« Reply #9 on: February 21, 2009, 03:00:19 PM »
Quote from: Alan F. on February 21, 2009, 02:53:22 PM
Is it possible that a PO doubled up on the copper exhaust gaskets?  That would make your studs seem a bit short.

Nope. I pulled the copper out of there personally this morning and replaced with new. I think I'm being a baby  ::) Back to it.
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Offline Bido

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Re: Kerker fit up - HELP!
« Reply #10 on: February 21, 2009, 03:19:19 PM »
No doubt they can be a #$%* to put on the first time I tried it I had the bike on the centerstand that was a mistake the pipe hits the centerstand and makes it almost impossible to get the pipes lined up correctly. My set was new and came with a flat bar that connects the muffler to the shock mount I thought that it was a #$%*ty setup but noticed that when you put the bike up on the centerstand the pipe hits the stand the hanger has some flex. I think it was designed for that reason.

Good Luck
Bido
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1978 CB750 Supersport F3
1981 CB750 K

Offline ev0lve

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Re: Kerker fit up - HELP!
« Reply #11 on: February 21, 2009, 06:11:34 PM »
Sorry for the whinging there. Just couldn't come to grips with the exhaust ports not visually lining up or having to take a rubber mallet to it. Replaced the studs with some I got from Tacoma Screw and they are plenty long.

Banged away at it and... it's on! Many many thanks for talking me off the ledge  ;D

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Offline ev0lve

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Re: Kerker fit up - HELP!
« Reply #12 on: February 21, 2009, 09:48:00 PM »
Quote from: Bido on February 21, 2009, 03:19:19 PM
No doubt they can be a #$%* to put on the first time I tried it I had the bike on the centerstand that was a mistake the pipe hits the centerstand and makes it almost impossible to get the pipes lined up correctly. My set was new and came with a flat bar that connects the muffler to the shock mount I thought that it was a #$%*ty setup but noticed that when you put the bike up on the centerstand the pipe hits the stand the hanger has some flex. I think it was designed for that reason.

Good Luck
Bido

Mine's on the centerstand and no issue there. Had the strap on initially and then removed it to be able to swing it around at will. Started on one side, found a few flanges had turned upside down, straightened them out and then just whacked it on the studs.

I think the metal memory thing (or whatever the right term is for that) had to be going on. Always had used bikes that already had the pipe on it so never new and never that had been off the bike for any considerable amount of time. This one's been in the garage since January and who knows how long before it got to me. Learn something (or 5 or 6 somethings) everyday  ;D
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