Exhaust I need some advice on an exhaust idea...

Discussion in '2-Stroke Engines' started by DJChrisp, Oct 26, 2009.

  1. DJChrisp

    DJChrisp New Member

    :idea:My idea is to take a long piece of copper tubing and attach it to the muffler output and run it all the way back an inch past my back tire. How will this affect performance. Has anyone else done this. Any ideas theories or bonafried results would be great.
     

  2. AussieJester

    AussieJester Member

    if its the size of the pipe on the 'muffler' i think it will cause too much back pressure and be detrimental to the motors performance. You can do similar with mufflers when they have expansion chambers connected to them, they are called "stinger" it is a length of pipe at the end of the muffler that can be slid in and to alter the engine's power characteristics, i doubt what you wish to do would have a positive effect however you need to have an expansion chamber for this too work.

    KiM
     
  3. DJChrisp

    DJChrisp New Member

    What about a larger dia pipe? Could that help with back pressure issues?
     
  4. loquin

    loquin Active Member

    the problem is that 2-strokes are VERY sensitive to exhaust sizing - length/diameter/volume. A change may help, it may hurt, may not matter, and may lead to the destruction of the engine after a while...
     
  5. The use of copper may not be the best idea ever. Years ago I fabricated an exhaust system out of copper on a Honda. The exhaust noise coming from the end of the pipe was no louder, but the pipe resonated like a bell ringing. It was not at all a pleasant sound.
     
  6. AussieJester

    AussieJester Member

    Rather than just asking questions and 'guessing' it would be better if you read up on how the tuned pipes (expansion chambers) on two strokes work and why they work then you will have a better understanding of the effects of pipe lengths on them. Cutting pipe and jamming it on the end of your standard setup isnt going to do anything for performance. Pipe length and also pipe shape is is critical to a 2 strokes performance. Adding an expansion chamber to a two stroke increases its power output by improving the volumetric efficiency. The engines uses the burn gases in the expantion chamber to assist in filling the cylinder for the next firing cycle. The size ie volume of the expansion chambers must be matched too the engine it is used on to get maximum performance.

    Here's a diagram that will better explain the function of a tuned pipe for you

    [​IMG]

    By altering the 'stinger' you can alter the amount of back pressure thus flow back into the cyclinder, too much or too little back pressure will result in decreased performance. Its not as simple as 'whacking' a tuned pipe on a motor the pipe must be designed for the motor to get best results.


    Best of luck

    KiM

    EDIT: appears the animated diagram above is no longer 'animated' strange... ?
     
    Last edited: Oct 26, 2009
  7. DJChrisp

    DJChrisp New Member

    The idea wasn't necessarily to boost performance in any way but to redirect the exhaust to the rear of the bike without goofin' up my motor due to back pressure issues. Your post on the other hand was very informative and I'm sure it will come in handy down the road some day.
     
  8. AussieJester

    AussieJester Member

    My apologies i assumed you were trying to improve performance. You could lengthen the pipe before the muffler it will still have a detrimental effect on the performance
    but not as much as after the muffler...

    Best of luck


    KiM
     
  9. DJChrisp

    DJChrisp New Member

    Looks like I have a reason to play with the welder. Thank you Aussie you've been very helpful.
     
  10. 2door

    2door New Member

    You can use 1/2" OR 3/4" electrical conduit (EMT) to fabricate a long pipe. I like to use the kit supplied exhaust pipe and flange, cut it from the muffler then use the EMT and fabricate a new pipe back to where I want the muffler to be. I use TIG but a wire feed, MIG, welder will also suffice. Conduit benders are cheap and available everywhere, Ace Hardware, Home Depot, etc. It takes a little practice to learn how and where to bend but after you get the hang of it you can fabricate a custom exhaust that will look good and function well.
    Tom
     

    Attached Files:

  11. professor

    professor Active Member

    2 door- I really like the look of your bike!
    Note- try to not breathe the smoke from the tubing weld, like galvanize, it is bad for you.
     
  12. 2door

    2door New Member


    Welding galvanized coated metals is not a good idea unless you're aware of the hazards. I should have noted that. Thanks for reminding me. Here's an old pipefitter trick: After welding galvanized coated metals and if you breathed any of the fumes, drink a good quanity of milk. It will counteract the effects of the toxins produced during the welding process. The best way is to weld in a well ventilated area, preferably outdoors so you do not to breath the fumes. Hope that helps and thank you again for the reminder.
    Tom
     
  13. AussieJester

    AussieJester Member

    2Door...Love the first bike mate...hrmz...dunno about the second though the seat although im sure would be very comfortable just don't look quite right IMHO...

    In regards to glav, simply use a flap disk to remove the galv from the area to be welded...cheers for the milk tip hadn't heard of that before an **** have i welded some glav in the past in steel fab industry...

    KiM
     
  14. 2door

    2door New Member


    Aussie,
    Thank you. That seat was a rough prototype that will be redesigned while I'm painting the bike. I did the seat cover, stitching it by hand because my wife's sewing machine wouldn't handle the thick vinyl. A friend who owns an upholstery shop is making the new seat. It will have more of a cafe racer look to it. You are correct however; it is very comfortable.
    Tom
     
  15. clay

    clay Member

    you tig emt!? i'm calling bs. no one who can tig would waste the argon.
     
  16. 2door

    2door New Member


    Yeah...whatever.
    Tom
     

    Attached Files:

  17. AussieJester

    AussieJester Member

    [​IMG]



    OWNED... nice welds there Tom ;-) What a ridiculous comment to make Clay... do you even know
    how too weld yourself? Iguess not with such a stupid remark.
     
  18. spad4me

    spad4me Member

    Just my 2 cents which is what my happytime exhausts cost.

    I use the factory flange and a 3/4 male emt setscrew connector, plus a 3/4 threaded plumbing coupling, with a ace hardware lawn mower muffler.

    I use cut up pieces of old handlebars with rings from an old seatpost as couplers.
    To fab up a custom exhaust pipe that ends at the rear of the back wheel.
    I use a hose clamp at the kick stand base to steady it.
    Lost of welding.
    I use the cheapest setup an oxy acetylene welder LOL.
    No stink for me plus low noise
     
  19. craisin

    craisin Member

    can I tell you about burning my leg on the muffler of my YB125 Yamaha twice.
    Took a lot of time to heal.
    Thought of a hot copper pipe and its potentual to tranfer heat into a human leg :tt1:
     
  20. clay

    clay Member

    24 ga stainless thats .020"


    [​IMG]


    mild steel on my first bike
    [​IMG]

    stainless pipes for a customer
    [​IMG]

    [​IMG]

    stainless on my daily ride
    [​IMG]
    [​IMG]
     
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