7/8" tubing for exhaust?

Discussion in 'General Questions' started by SuedePflow, Jun 12, 2013.

  1. SuedePflow

    SuedePflow Member

    I want to make my own exhaust. I plan to reuse the flange and muffler and just redo the piping in between so that I can reposition the muffler. The tubing is 7/8" (.875") O.D. I could probably make 1" O.D tubing work as well.

    Does anyone know where I can find a steel u-bend or j-bend in either diameter? I've been looking all morning and I'm coming up short...

  2. Purple Haze

    Purple Haze Active Member

    If you have access to a conduit bender you could make your own. 7/8" tubing bends rather easily, and you could make custom bends to fit your exact bike, instead of working with universal-fit stuff, which universally fits nothing. Just my opinion.:idea:
  3. SuedePflow

    SuedePflow Member

    A conduit bender will work on mild steel tubing with a .058-.065" wall thickness?
  4. Purple Haze

    Purple Haze Active Member

    It'll work as long as you don't try to bend too much of a radius. Conduit benders only go about 90 degrees anyway, if you need more, make multiple bends, and if necessary, do some splicing if you have a welder. You need to talk to Headsmess, he does some elaborate exhaust work.
  5. HeadSmess

    HeadSmess Well-Known Member

    ha ha, thanks for the comendation :)

    depends, too smoke or forepoke?

    go for it on a 4stroker. get on the pushy and go visit junkyards/scrap yards, etc. youre trying to find table legs, chair legs, etc... they usually have nice 90 degree bends, etc. imagination helps :)

    two poker will work fine with a straight pipe but youll be forever lacking in performance.

    in that regard, im always fiddling with making new pipes, trialling new layouts and designs. correcting mistakes.

    i dont feel the need to move on from a 48cc, or do any other mods as a general rule. my pipes are effective enough.

    you can make them with pretty mediocre equipment if youre determined ;) i once used a fence starstake, a chisel and silver solder...

    once again, the scrapyard is your FRIEND! amazing what youll find.
  6. SuedePflow

    SuedePflow Member

    I ended up buying another set of handlebars to chop up and form an exhaust. I'm just surprised that nobody out there is offering j-bends, u-bends, or any other raw material to use to make exhausts for these. I was hoping one of the moto-bike vendors had DIY material.
  7. SuedePflow

    SuedePflow Member

    Built my handlebar exhaust today. Turned out pretty nice.




  8. Purple Haze

    Purple Haze Active Member

    Nice job! I wish I could weld that neatly. Thanks for posting the pics, now I'll see if I can rip off your idea.:jester:
  9. HeadSmess

    HeadSmess Well-Known Member


    that looks surprisingly good. is that an upside down intake manifold i spy?

    find a 28T off a lil kiddy bike for that rear sprocket! is ideal for 20" rims. as it is, you got hill climbing grunt :)
  10. SuedePflow

    SuedePflow Member

    Yup, TIG'd it.

    I modified the manifold too to get the carb level. Chopped it at an angle, turned out an extension on my lathe, and welded it up.

    Manifold pic

    Pic mounted

    It tops out at 20 mph the way it is right now. Where can I buy a 20-tooth sprocket that is already drilled to bolt right up like this one?
  11. HeadSmess

    HeadSmess Well-Known Member

    i looked for stray copper coated wire and all i could see was a tig rod :) whats the swingarm in the bground off of?

    sprockets...i have no idea where to buy them... all i know is that the 12.5" wheel kids bikes(the tiny ones) usually have a 28T on the cranks. needs to be bored and drilled. note that its HARDENED. so carbide boring bar and either really good(expensive) HSS drillbit or a masonry bit sharpened like a metal drill... you only need 3 holes ;) 6 is better, 9 is overkill. assuming you have 36 spokes.

    nice time to machine up a plastic bush for the hub to hold sprocket nice and central.

    the 16" kids bikes have 36T. usually. all the ones i gut do :) about right on 26" rims for speed.

    not sure if 20t would fit within the existing bolt pcd... and possibly way overgeared with only 8:1 redux in total. a 28t gives just under 12:1. much better for usability :)

    i had a 33t from a place i worked that he had laser cut. teeth werent terribly pronounced(bad drawing), but i never had a chain slip on it!

    which just reminded me of another thing i can make with my plasma cutter when i get it CNCd! rear sprockets! any teeth, any pitch, any pattern, up to 8mm... nice :) in ANY MATERIAL!

    what sort of TIG is it?
  12. SuedePflow

    SuedePflow Member

    Good to know that I don't need to use all 9 holes to mount the sprocket. An alloy sprocket would be easier to drill and bore. I don't need to run hardened steel, do I?

    I'm welding with a Lincoln Invertec V160T. My little welder that could. haha

    The thing in the background is a tubular front k-member that I fab'd for a buddy's race car. I still need to make steering rack mounts for it and send it off for powdercoating. It's been on the backburner since I've been working on this bike. :) Here's a better pic of it tacked up prior to being welded in the jig: PIC
  13. Scootmeister

    Scootmeister Member

    I started out using 3/4" thin walled conduit for all of my exhausts. It's cheap, readilly available, easy to bend and easy to weld. On ocassion I used old handlebars and kit components. Those exhausts worked great until I started installing performance enhancing components. If you intend to do any tuning, you might want to consider going to 7/8" or 1". It's amazing how much deeper these engines breath when restrictions are removed. You can still bend 1" using a manual conduit bender with a long handle. just my 2 cents worth.
  14. SuedePflow

    SuedePflow Member

    The handle bars that I used were 7/8" diameter and decently heavy wall thickness too. I didn't measure it, but it was around double the wall thickness of the exhaust tubing that the kit came with.

    I might consider building a 1" exhaust down the road. Something shorter and with a smaller, less restrictive muffler.
  15. Scootmeister

    Scootmeister Member

    I'm envious of your welding skill, as well. I spend as much time grinding as welding when I use my old stick welder. BTW, your handlebars are 7/8" OD, when I recommend 7/8 or 1" I'm referring to Inside Diameter. If you consider that your bars are extra thick you are probably looking at an inside diameter of 9/16 or 5/8 which is comparable to kit exhausts which are very restrictive. Part of the fun is experiementing to see what works best.