What to use for exhaust pipe?

cfh

Well-Known Member
#24
I make exhaust all the time for my Tecumseh powered flat head mini bikes. I use 7/8" stainless steel tubing with a .065" wall thickness. And a bender as was shown above. TIG weld everything with stainless steel filler rod. It works great. Also use 1 3/8" tubing on the end of the 7/8" to create a "Harley" end to the exhaust. I have a 12 ton harbor freight press and a Die i made that narrows the 1 3/8" to about 1", and then fill weld it to the end of the 7/8" tubing for a nice look. I do not argon fill the inside of the exhaust to prevent "sugaring". If you keep the temperature low, and move fast, there's just no need for it. Also it's on the inside of the tubing, so if you get a little sugar it's really no big thing. A die grinder can take care of that if you think it's needed.

Bender:
https://www.ebay.com/itm/VEVOR-Pipe...2349624.m46890.l49286&mkrid=711-127632-2357-0

The 7/8" tubing:
https://www.zoro.com/zoro-select-78-od-x-6-ft-welded-316-stainless-steel-tubing-5lvp4/i/G0511725/
The 1 3/8" tubing:
https://www.zoro.com/zoro-select-1-38-od-x-6-ft-welded-304-stainless-steel-tubing-5lvn4/i/G1852356/

As for the flange that goes on the engine, i have Autocad file i send to https://app.sendcutsend.com to get those made of stainless steel 1/8" thick.

Here's an example of a stainless exhaust i've done:
http://www.pinrepair.com/minibikes/p/speedway1972scarab_mine5.jpg
http://www.pinrepair.com/minibikes/p/speedway1973scarab_mine3.jpg
I like doing a slight bend on the end of the exhaust with the "harley" end (1 3/8" tubing) and come out the side, as this breaks the sound up and makes the bike less loud (for an open exhaust.)

If you want to minimize bends you can go this way too:
http://www.pinrepair.com/minibikes/p/speedway1973scarab_mine1.jpg
It's straight out the back style with the "harley" end (1 3/8" tubing.) But this is louder as the sound doesn't get broken up on the way out.

I've also used some 'pre bends' like from 7/8" handlebars, but you won't get stainless steel doing that:
http://www.pinrepair.com/minibikes/p/arco1970_easyrider_mine1.jpg
 
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#25
The past few months I’ve been gathering parts to fabricate an exhaust for my Briggs and Stratton / Doodlebug project.

I’m building a bender out of a bottle jack, angle iron from a bed frame and wheels that I cut on a wood lathe.
Bender Parts.jpeg
I know it’s hazardous to weld galvanized metal, so I was just gonna use these parts to practice bending, and make the mock-up.

I’m still looking for a 3/4” pipe thread coupling that is not galvanized like this one for electrical conduit, nor as large an OD as a black plumbing fitting.
Anyone know of a source?
Exhaust Parts.jpeg
I'll post pictures of my progress, but 900 other home projects have gotten in the way lately.
 
#26
I use 1" stainless tube. I get it at Metals are us which is local to my area. I have a tube bender so it is pretty easy to make them. I use a tig welder to weld them but if you have a gas mig welder you can get a spool of stainless wire and weld with it. I have had some issues with not being able to bend a real tight radius so I find prebent 90 bends on ebay.
You do very nice work. Used to do a lot of 3A sanitary welding for food and or hospitals with 316 tubing I’m going to purge and fuse and see how it works.
 
#30
I usually just sand off any galv coating, i also have a respirator that i use for that. I used to weld very heavy hot dipped galvanized coating every day at work and zero issues. Getting galvi sick is no fun, back in high school they told us to drink milk lol. It's basically zinc poisoning and i've had it a couple times years ago. Feels like the flu.
 
#32
Without using any benders or muriatic acid to remove galvanizing, just find some chrome bicycle/motorcycle handlebars 7/8”-1” and cut out the bends you want or that fit your build, then you only have one weld to worry about(at the flange) and you’ll have a sweet chrome exhaust!

Side note: chrome is not the best/healthiest to be inhaling during welding so wear a respirator
 

cfh

Well-Known Member
#33
Why are you guys using galvanized tubing and pipe? I posted a link to 7/8 inch diameter .065 wall thickness stainless steel. It’s not that expensive. That’s the proper material to use, and it doesn’t rust and you don’t need to treat it or paint it. And 7/8 is generally the diameter you want. 3/4 is too small, 1 inch is just too big

here’s a 7/8” exhaust just did on a 1972 Speedway blue Angel. The end of the pipe uses a Harley end, that’s 1-3/8 inch stainless. But the rest of it is 7/8 inch. I used the tubing bender I posted above to make this

http://www.pinrepair.com/minibikes/p/speedway1972blueangel_mine5.jpg
 
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2old2care

Active Member
#36
Awesome list!
Thanks, Cfh.

Anybody have a good Tig welder to recommend?
I'm just starting to teach myself to TIG weld - I bought a Primeweld 225 amp machine, but I don't feel that I should recommend it, as I haven't used it long enough. It has a pretty good reputation, seems fine so far, and has a LOT of settings, that I still need to get my head around.
One thing - If you ever plan to weld aluminum with TIG, you'll need to get a machine that has an AC function, and those are usually a good deal more expensive - DAMHIKT
 

cfh

Well-Known Member
#37
TIG welding takes practice. I have both MIG and TIG machines. and the mig was far easier to master, but i hate the thing. Tig is just so much more skillful and satisfying. The biggest problem people have with Tig is using too much heat (especially on stainless steel.) But there's tons of good videos on youtube to help learn.

i bought a Lincoln Tig welder. it's 'old school' type transformer model. There really aren't a lot of settings. I also have one of the new fangled Tig welders with all the settings... but i use the Lincoln far more often. Having all those setting is great for Aluminum. but for steel, you just don't need all that stuff.
 

cfh

Well-Known Member
#39
i think the only feature on a Tig welder that you must have is a high frequency start up. The "scratch" start, all in one welder, are no good. Also i like the old school transformer tig models (lincoln, miller), as there's just nothing to go wrong. the new models with computers have a lot to go bad, and you're at their mercy if it goes south.

i got my lincoln transformer tig machine on facebook. it was $750 with a cart and a 4 foot tig tank. all i had to buy was a helmet...
 
#40
i think the only feature on a Tig welder that you must have is a high frequency start up. The "scratch" start, all in one welder, are no good. Also i like the old school transformer tig models (lincoln, miller), as there's just nothing to go wrong. the new models with computers have a lot to go bad, and you're at their mercy if it goes south.

i got my lincoln transformer tig machine on facebook. it was $750 with a cart and a 4 foot tig tank. all i had to buy was a helmet...
This is great info for me. Thank you.

Yes, I'm only decent at mig once I've tested and practiced on 4 or 5 coupons first -- to master the particular weld I'm getting ready to make. The welders with computers and a dozen knobs give me a panic attack just looking at them. Old school is bound to be more my speed.
 
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