Author Topic: Pre-Project to the Project: Custom 4-4 Exhaust (Read 2331 times)

rbmgf7 · « **on:** May 23, 2011, 08:48:50 AM »

In my endeavor to get my 72 CB750K running after three years, I finally have time to work on it.

I got this guy with three other 750's (a 73, 74, and 75F). Two others had titles but I just wanted one. Unfortunately he wouldn't part with just one so I got all four and sold the other three.

Well, onto the pre-project:

I was always set on a 4-4 exhaust but thought the OEM's on eBay were just too expensive. My next best bet was Benjies stainless set. I was commited to buying his exhaust when I did a little research on ways I could build my own. So, after I did some homework, I came to the conclusion to build my own.

I went with this guy which I'm sure a lot of you have came across and probably pondered the same thing:

Yes, the infamous Harbor Freight tubing roller. Seems sturdy but as you can see, it's hard to determine your bending radius which is why I thought of this to help control the adjusting die:

Yes, it's a degree wheel for adjusting cams and it fits like it was made for it. As far as controlling the rolling distance, I was going to figure a way to mark measurements on the large crank wheel. The roller came with 1", 1.5", and 2" dies. I decided to go with 1.5" since that's relatively close to OEM.

I also have a CAD program on the way. Before I even begin the first roll, I'm going to draw the frame and engine into the program to help get measurements and eliminate trial and error.

Unfortunately the roller can only roll 1.5" to a radius of 7" (or so it claims). So, I looked into mandrel bends online. To determine which radius I needed, I did a little mock-up work:

The smaller one is 4" and the large is 6". I went with the 4" through Jegs. They had 180 degree, 16 gauge which I could use one piece for two pipes...I got three just in case...and it's been a month since I ordered them and I'm still waiting.

The exhuast pipe I ordered through Wicks Aircraft; the cheapest 4130 you'll find since the locals were going to charge me $8/ft. I went with 1.5" OD 0.065. A little thick but robust enough to handle road debris. I ordered inner and outer sleeves to butt weld the headpipes and use for bolting the flanges.

I talked with Jake at Cycle X and they hooked me up with a set of flangs which work great.

I purchased a set of Emgo shorty reverse cone mufflers from eBay.

My crude mock-up:

ksbrenn · « **Reply #1 on:** May 23, 2011, 08:59:45 AM »

WAAAAYYYY cool...I'll be watching this one close!!!

just for fun...
kerry

greenjeans · « **Reply #2 on:** May 23, 2011, 09:07:01 AM »

Also - check into cone engineering for exhaust pieces & megaphones.

http://www.coneeng.com/

I'm watching - I have 2 750's that will need some sort of pipes.

JimJamerino · « **Reply #3 on:** May 24, 2011, 09:00:04 AM »

If you're up for it, PM me when you hit Rapid City. It'd be awesome to meet another forum member in person!

Syscrush · « **Reply #4 on:** May 24, 2011, 09:06:23 AM »

Exciting! Good luck with that bender and the rest of your project.

rbmgf7 · « **Reply #5 on:** May 24, 2011, 12:41:57 PM »

Quote from: greenjeans on May 23, 2011, 09:07:01 AM

Also - check into cone engineering for exhaust pieces & megaphones.

http://www.coneeng.com/

I'm watching - I have 2 750's that will need some sort of pipes.

Nice. I wish I found this place earlier because this is what I was looking for when looking into mufflers. Since the headpipes were going to be raw, I was just going to paint the system them with high temp paint. I'll have to order me a set now.

rbmgf7 · « **Reply #6 on:** July 20, 2011, 09:45:46 AM »

Well, its been a while since I started this endeavor. It took forever to get some mandrel tubing for the downpipes. Jegs was giving me the runaround for two months before I finally cancelled the order and got a refund. I found another manufacturer who makes mandrel bends as well as raw megaphone mufflers. I'm going to try and attempt one muffler this weekend. It'll be guess work since I was unable to get ahold of a CAD program. Hope all goes well

bert96 · « **Reply #7 on:** July 20, 2011, 12:20:08 PM »

Where did you get your raw megaphone?

I have found this one, http://www.megsexhaust.com/conical_products.html

Did you find a cheaper place?

Bert

bert96 · « **Reply #8 on:** July 20, 2011, 12:21:38 PM »

opps! i just saw that greenjeans post this site!

...sorry!

Bert

Gaucho · « **Reply #9 on:** July 21, 2011, 05:35:02 AM »

I did order a kit for the four cylinder headers from: http://www.coneeng.com/. At the same time I purchased their template to mark pipes and then cut at an angle, simplest tool available for the job.
The quality is fantastic and the shipping was both affordable and fast. I'm not related in any way to them, just a happy customer.
I'm going to use this kit for a project on parallel twin. For your project you may want to look into the V8 kit.
Gaucho

greenjeans · « **Reply #10 on:** July 21, 2011, 08:55:34 AM »

Quote from: Gaucho on July 21, 2011, 05:35:02 AM

I did order a kit for the four cylinder headers from: http://www.coneeng.com/. At the same time I purchased their template to mark pipes and then cut at an angle, simplest tool available for the job.
The quality is fantastic and the shipping was both affordable and fast. I'm not related in any way to them, just a happy customer.
I'm going to use this kit for a project on parallel twin. For your project you may want to look into the V8 kit.
Gaucho

Sorry to hijack, but... You have any photos ? Templates ? please explain

rbmgf7 · « **Reply #11 on:** July 23, 2011, 12:34:43 PM »

Starting to look good. Spent an hour and rolled one tube past 90 degrees (after 45 degrees it became a pretty good workout!). Went ahead and mocked it to my spare 750 and it looks about right where I want it. I'm going to order some 180 degree mandrels in 4.5in radius. I was going to order the 180 but got 90's at the last minute. I can't roll much further if I expect to mate it to a 90. Using a 180, I'll have to make a cut past 90 to butt the mandrel to the tube.

You'll have to excuse the layout on the mockup since I can't hold the tube in position and take a pic from afar. The good thing is I may be able to get two pipes out of one roll which would be great. I'm liking the tucked in profile where he tube will channel underneath the frame. It'll give me plenty of clearance.

bert96 · « **Reply #12 on:** July 24, 2011, 03:06:04 PM »

I don't want to hijack but,here what i found,maybe it could help some guys here who would like to do their own mufflers.

http://www.theflyingbanana.com/mufflers.htm

Bert

rbmgf7 · « **Reply #13 on:** July 31, 2011, 12:40:57 PM »

Steady as she goes. Made a little more progress. Managed to align and cut the headpipe to the downtube. Lucked out and got it perfect.

It aligns well in the back to butt the megaphones so each exhaust pipe is going to be a one peice. Can aluminum tubing be used for the baffle? Never seen one and can't figure why not.

Currently in a stalemate until I can get the other CB running again so I can get the pipes and a bike to the shop to weld it all.

greenjeans · « **Reply #14 on:** August 01, 2011, 11:34:38 AM »

I like that bend - very smooth and gracefull. I'm watching this one. You might have a customer.

Flying J · « **Reply #15 on:** August 01, 2011, 02:47:50 PM »

Im interested. I like 4-4 as well.

Retro Rocket · « **Reply #16 on:** August 01, 2011, 03:25:14 PM »

Subscribed

Alan F. · « **Reply #17 on:** August 01, 2011, 05:59:49 PM »

I'm subscribing too, darn nice progress!

Bluegreen · « **Reply #18 on:** August 01, 2011, 06:29:57 PM »

Very cool !! Subscribed !

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Author Topic: Pre-Project to the Project: Custom 4-4 Exhaust (Read 2331 times)