Topic: Time sensitive: need help, mocking up CR750 exhaust

[Doctor_D]

We're here in the shop getting ready to tack-up my exhaust and rearset mounts.

The exhaust is boggling our minds.  Simon, Mark or others... I need detailed pictures of the exhaust with the fairing removed.

How much clearance should there be to the rear axle from the megaphones?

The outside header pipes seem a bit splayed-out to get decent alignment with the megaphones.  Can I get a front-view minus fairing?

I have to lose my sidestand, don't I? Not the best on a dual purpose street/track bike. What are my options here?

Many thanks for everyone's prompt help...

[Doctor_D]

Jeez, thank for the help folks...

$1200 in labor today and we couldn't get the pipes right. All the collars on the swarbrick headers were welded crooked - canting slightly to the left. The blind arse who welded them better not run into me  in another life.

[Doctor_D]

Really, no one has anything to offer?  We've got 22 pages of homage to CR750's, and no one can show me the best way to mount the 4 into 4 pipes?

In Mick Duckworth's book, I can see a smallish tab, seemingly on a red M3 (referred to in the book as "M3's number one"), near the rear of the megaphones, joined by a pin that's retained by a cotter pin.  It looks also like the top megaphone has a bracket welded to it that is then mounted to the frame. Is one connection between the top and bottom megaphone sufficient?

The mega's appear to be welded to the headers and not clamped, true or false?

[napoleonb]

These are the pic's i have got.
None of the bike's are mine by the way, and i could not tell you which is the most original way of mounting.
Hopes it helpes you.


















These are original foto's:

[Doctor_D]

Thanks napleonb.

The pic from Simon's website has me curious - and I really wish he'd chime in here - as the #1 and #4 header pipes have torch marks on them.

http://www.moonpie.co.uk/cr750_exhaust.jpg

The resolution is so poor that I can't tell what I'm looking at.

Were they heated and bent? Cut and welded? (Am I correct in remembering that you can fill tubes with sand to keep the radius somewhat consistent while heating and bending them?)

[napoleonb]

As far as i understand headerpipes 1 and 4 indeed have to be modified in order to clear the fairing .


This can be done by bending and welding, i myself would not try to heat and bend the headerpipe into one piece not even with sand to fill the inside.
I have done quite some heating and bending with sand filled pipe's and you can do quite well when you have got a perfectly machting template over which to bend the pipe.
My choiche would be to bend several pipe's and weld them together.

The mufflers are connected to the bolt on which the brake and gear shifter rotate. (beneath the footrest)
As far as i know all the 4 mufflers have got a unique mounting plate attached to them, so two are always on top of each other.

Hopes this information will help, but as mentioned before i have not yet made an attempt to build and attach them myself.

[kos]

THE PIPES FROM SWARBRICK ARE NOT GOING TO FIT UP TIGHT AND "NESTLE" TOGETHER LIKE FACTOTY PIPES. EACH OF THE PIPES ARE DIFFERENT FROM THE OTHER WHEN YOU ARE SPEAKING ABOUT HONDA CR PIPES OR ROB NORTH PIPES.

THE TWO OUTER PIPES CURVE IN TO GO ON INSIDE OF THE FRAME DOWN TUBES AS SHOWN IN THE PICTURE POSTED BY NAPOLEONB.

EACH SET OF RIGHT AND LEFT SHARE A SINGLE BOLT MOUNTING AT THE REAR OF THE REASET BRACKET.

THEY WAY THE SWARBRICK MAKES THE PIPES IN ONLY TWO PIECES. FRONT PRIMARY PIPE AND THEN STRAIGHT MEGAPHONE WILL NOT MAKE FITMENT VERY EASY.

ROB NORTH FILLS PIPES WITH SAND AND MAKES EACH MEGAPHONE ON A BIKE TURNED UP SIDE DOWN. EVEN THE SAND HAS TO BE A SPECIAL  TYPE.

Ex flanges should not ever be welded to head pipe!.

You cannot use the center stand and or its mounts on frame.  Must be removed and ground smooth.



KOS

[MRieck]

Did the Heritage Honda use Swarbrick pipes?

[lordmoonpie]

Doctor D - first question is what swarbrick pipes do you have? The headers on my bike which accoutns for about half of the pictures Nap has posted up above are Swarbrick CR750 curved headers and they are absolutely bolt on parts, no modification other than shortening to get the megas to fit right. The megaphones I sell are curved and formed to weld or collar bolt to swarbrick headers. They require two small curved brackets to attache the megaphones to the correct CR750 footrest brackets but they DO NOT attach at the point where either the pedals or the footrests attach, they fix to a specific mounting hole close by.

If you have straight swarbrick megas and are trying to make them fit then it's a hell of a job. I know a fabricator who did it and did a great job but it took him well over 100 hours of tiny cuts and welds to make it fit. Formed megas take all this pain away. If you send me your email address on a PM I will post all the high res. pictures of my bike for you to see how I did it. I also have a handful of works photos too of for example the bike upside down to show routing etc.

Here's a few to start with...note that the lower mega is about 10mm away from the spindle end and spindle nut each side - it's very very tight.

[lordmoonpie]

Here's some bracket pics - lower res tan I have because of this site restriction...very hard to see the brackets but the lower is a double anchored bracket that comes together to form one thick plate - 3mm mild steel. The top mega uses a simple angle plate - 90 degree that meets up with the double thickness lower bracket to bolt near the footrest mount. This is the first pic...

[lordmoonpie]

These are my standard Swarbrick CR750 headers bolted on - the only reason you can see bare metal on the two middle pipes is where I had an extra inch welded in to clear my deep sum underneath. Otherwise these are exactly the same as they dropped out of the packet from Dave Swarbrick, bends in one and four pot as well which you can clearly see here. They run very close together...as you can see from the lower pics. Hope that gives you soem pointers. It could be that if you are trying to fit straight megas and making them fit you just have a mountain to climb...

[lordmoonpie]

Oh just one point on originality - although my pipes are newly fabricated they are copied off a full works system that the fabricator had in his hands at the time - I've not seen anything closer to the kit pipes than these...

[Doctor_D]

Simon, thanks for your detailed reply. I bought these parts from you in February of this year.

The set you sent have four identical headers.  Number 1 and number 4 do not tuck in like they do in your pictures.



Did I get a mismatched set?

[Sam Green Racing]

Hey Doc, sorry to be late coming in but a search might have helped.

http://forums.sohc4.net/index.php?topic=12070.0

Sam.

[lordmoonpie]

Doctor D - in that case it must be an incorrect pair of headers. Send them back to me and I'll get on to Swarbricks to get them replaced asap with correctly bent ones! PM sent with details, just let me know they're on the way and I'll have some replacement ones back out to you immediately you confirm.

[lordmoonpie]

David - just one further question, the headers should be numbered with black marker when they come out of the packing, did yours have any numbering on them?

[napoleonb]

Here's some bracket pics - lower res tan I have because of this site restriction...very hard to see the brackets but the lower is a double anchored bracket that comes together to form one thick plate - 3mm mild steel. The top mega uses a simple angle plate - 90 degree that meets up with the double thickness lower bracket to bolt near the footrest mount. This is the first pic...

Simon,

Could you sent me all the high resolution pictures you have got of the works racer?
The last pictures with the specifics of the mounting plate, are those original?

[Doctor_D]

David - just one further question, the headers should be numbered with black marker when they come out of the packing, did yours have any numbering on them?

No, they did not have any numbers on them out of the packaging.

I'm glad we cleared this up.

[lordmoonpie]

David, if the headers are not numbered there is clearly a problem with them. Send me the HEADER pipe that attaches to one and four cylinder and I'll send you a pair from my spares kit while I take it up with Swarbrick. You should have these from me by Monday so you can carry on and I'll have the interesting discussions offline. 
Sorry you've had this angst - it'll get sorted!

Note that the megas you have are identical - you may only need to trim the top mega by a few mm to get the look you want in terms of stacking the pipes and open ends. The routing differences are taken care of with the headers....when you have the right ones!

[lordmoonpie]

Here's some bracket pics - lower res tan I have because of this site restriction...very hard to see the brackets but the lower is a double anchored bracket that comes together to form one thick plate - 3mm mild steel. The top mega uses a simple angle plate - 90 degree that meets up with the double thickness lower bracket to bolt near the footrest mount. This is the first pic...

Simon,

Could you sent me all the high resolution pictures you have got of the works racer?
The last pictures with the specifics of the mounting plate, are those original?

Nap,

the old B&W pictures I posted are as high res. as I have them unfortunately. The later colour ones are of the mounting brackets on my exhausts but as mentioned they are copied off a works set of pipes that the fabricator had in his hands at the time so not authentic, but a great replica...

[scottly]

Napoleon, where is the next to the last picture from? Is this an advertisement for a CR kit? Zooming in, about 2/3 down on the right side, there appears to be a right hand "C" type caliper bracket, similar to what came on my Seeley.

These are the pic's i have got.
None of the bike's are mine by the way, and i could not tell you which is the most original way of mounting.
Hopes it helpes you.


















These are original foto's:

[lordmoonpie]

Scottly - the second last picture is the cover of Cycle World which has the long CR750 article and this picture shows the full set of kit 970 parts to do the conversion. I'm pretty sure there's a PDF of the whole thing on this forum somewhere but if not, I have one locally I can post/email.

[Sam Green Racing]

It's posted in the Daytoa thread Simon but it don't work when you click on it.

Did you get my PM ?

Sam.

[scottly]

Thanks Simon. Could you post it on the Daytona thread? I'm sure I'm not the only one who would enjoy it.

[Tintop]

realize this thread has to do with cr750 4 into 4's.  however, I just started to install a set of Swarbrick 4 into 4's on my 550 cafe and any pictures of the Hailwood 500 would help, especially mounts.  so far the loose 1st trial fit went well, only #1 header looks like there might be a slight issue.  pictures are posted in my build thread.