DIY Exhaust help needed

R

rustreddesign

Been Around the Block
So I think I am going to attempt to make my own exhaust. The task seems rather daunting, but I think it's the only way to get things exactly the way I want. I have a few questions before I start though. FYI, I have a 1974 CB360.
1) what do I do for the flanges where the pipes meet up with the head? Do I weld onto the stock ones or is there a place to buy these?
2) where is the best place to buy exhaust pipe? I plan on using steel - nothing fancy. I will most likely throw a coat of header paint on them then wrap.

Thanks
 
buy j madrel bends in size you need (1 and 1/4 or so should do you well) and cut/ weld to how you want them. if your not good at welding, bring them to an exhaust place.


as for the flanges... you can weld on stock, or cut a bracket out of steel that you weld onto the pipe that you tighten onto the exhaust studs.
 
I just found this stuff on jegs.com - the price seems reasonable at $13.99. If I used this; could I cut it in the middle of the U-bend, add in a strait length between the two pieces and add a strait length for the tail section? Seems possible.
http://www.jegs.com/i/Patriot-Exhaust/737/H7007/10002/-1?parentProductId=892486

Basically, what I am trying to do is route my exhaust below frame/engine instead of outside of the frame. I have some shorty (12") mufflers that will nestle nicely underneath.
 
yes.

if it fits, then go for it.

remember; having it routed under bike means changing oil requires exhaust removal. plan accordingly.
 
No biggie. I already have to do that to get to the centrifugal filter in the crank case. I've seen the pipes that are held together with springs, but that's a little ambitious for my first set so I think I'll simplify and just deal with the their removal/installation every couple thousand miles.
 
There are better places than JEGS for mandrel bends.
You need to run pipe slightly off center than oil changes are not a problem
I think I have pictures of pipe I built on my build thread, (see sig)
 
don't cheap out and get U bends, the section in the middle of the U isn't circular as much as they'd like to tell you it is. get the 90' bends with the longer legs, and you can build the head pipes for the 360 with one weld in the middle, instead of two. welding to the stock flange might not work too, because the stock pipes are usually double walled, the cheaper aftermarket ones like mac are single walled, but the metal is really thin and would be tricky to weld to. what I'd do if I didn't have a lathe, is buy some 1 1/4" schedule 40 pipe and cut it to make your flanges. the actual od of that pipe should be 1 5/8 which I think is what the stock flange was
 
Do yourself a favor and try to mock up what you want as much as possible. I've built several exahust systems, including downpipes, for my turbo cars. JCWhitney is probably the cheapest for mandrel bent pipe and try to avoid sharp bends. Most local exhaust shops use a madrel to bend pipe but it is not mandrel bent pipe. Its press bent pipe. It makes a difference. Most places will swage an end for you if you buy the exhaust guy a coke and that will allow a slip fit. If you have a welder but want it nicer than tack your joints on the back side and have a pro TIG it up. A real welder charges about $40 an hour. I am lucky enough to have a speed shop local and they have a CNC mandrel bender. Don't forget your brackets too. I plan on DIY exhaust for my poor little CB 100...
 
Thanks for the good info guys. I was thinking the same thing about the U bends; if cut in the middle, it will be more of an elliptical shape. I'll probably go with the 90 degree bends. That said, I do want the headers to sweep back towards the frame so I think I will have to deal with some pipe that is not pefectly round. Nothing like jumping into a crazy project like this to get used to my new MIG.
As far as the flange goes; I need to take another look, but I believe the stock flanges are spot welded on so I may be able to drill out and reuse. The OD of the stock pipe is 1 1/2" using my caliper so that means it should fit the 1 1/2" OD single wall stuff I'll use for fabrication. This may not totally correct as I don't have the pieces in front of me, but I'll double check later. I'm going to take a look at crazypj's setup for some ideas - from what I've seen, that dude knows his stuff when it comes to 360's.
 
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