Exhaust 25 Cent Home-built Muffler End Cap in 10 easy steps.

Discussion in '2-Stroke Engines' started by daf, Mar 13, 2014.

  1. daf

    daf New Member

    Well I'm not sure where the derned thing fell off. And as much as I could always use a good excuse to go for another ride, the 7 inches of snowfall followed closely behind by an armada of snowplows made that possibility unappealing if not impossible.

    So I started looking at other people's end cap solutions, and people were REALLY ingenious. I tried the can thing, but it looked like garbage on the outside and just as crappy when i tried it on the inside.

    Then I saw this thread for a $3 Home made Muffler End Cap:


    I rushed to the store, bought a 2 inch fender washer and a locking nut (for 25 cents) and rushed home to repair the muffler..only to find out that the mounting stud is OFF CENTER! Not to mention..I realized that drilling a hole into the washer for exhaust was going to be daunting without a drill press and some good bits. I had neither onhand.

    Well I didn't feel like going back to the hardware store that day, so I just sort of stewed on it to see what I could come up with.

    Then I started making some lunch and opened a can of soup. That's when I got the idea to use the soup can lid as an end cap.

    1. First, I took the can lid and positioned it at the end of the stud and eyeballed it to make sure it would cover the whole exhaust hole. Then I hit the soup can lid with a hammer a couple of time to mark it (the stud underneath dents the can at the spot where we need a hole.)

    2. Now you can drill the hole out, punch the hole out, whatever you have handy and feel like doing. Just make a hole where the stud mark is. Make sure the hole is big enough for the soup can lid to go all the way down onto the stud and sit flush with the rim of the muffler housing.

    3. Hold the soup can lid completely still as you use scissors to trim off any soup can lid that sticks out past the muffler's rim. Let the outside of the muffler act as a guide for the scissors. When you're done, you should have a circle that is as big around as your muffler with a mounting hole in it.

    4. Carefully trace out a hole for the exhaust to come out. I used a sort of "semi circle" shape. Make sure to cut it smaller rather than larger at first. You can always make it larger as you tune your bike in. Also round off any sharp corners. You don't want to stab yourself with the thing while you're working.

    5. Take a washer with a large center hole that can fit over the stud and make sure the soup can lid stays flush to the exhaust.

    6. Add a spring washer on top of the washer.

    7. Put a locking nut on top of the spring washer and tighten the whole thing down. Make sure the soup can lid is centered on the open muffler end and sits flush with the muffler rim.

    8. Carefully press the edges of the soup can lid down until they go INSIDE the muffler just a bit. (I used a small standard screwdriver and tried to make mine flush with the muffler edge.) On mine, I also pushed them in farther near the exhaust hole so that the exhaust gases wouldn't blow the tabs out of the muffler which would have the effect of widening the exhaust hole.

    9. At this point you could JB Weld the inside lip of the muffler where the soup can lid meets the side of the muffler. Or just use it as is.

    10. I plan to cut the excess stud off, mask the outside of the muffler and the exhaust hole with tape, then paint the soup can lid, washers and locking nut black so it just looks like an open exhaust pipe.

    Good luck, ride hard and come home safe,


    Attached Files:

    piecepatrol99 likes this.

  2. piecepatrol99

    piecepatrol99 Member

    exhaust mod/repair


    I've used similar proceedures on my car. Sadly this isn't temp patch work I have a question on...

    1: I was wondering why the header pipe is a 1" opening but the tail pipe is only 3/8". Is this why I'm lacking power @higher RPM?
    2: Will enlarging the ID of the tail pipe help this issue?
  3. HeadSmess

    HeadSmess Well-Known Member

    1. makes em quieter. and if it was a tuned pipe...it would still be about the same size ;) they require the outlet to be small to work correctly.
    2. on these dodgy exhausts...it does something but not much, opening it up to 16mm or so. just realise you need to drill out the baffles to accommodate whatever pipe you replace the outlet with, if you choose to stick it all the way in.

    they lack power at ALL rpm, especially up high! :rofl:
  4. butre

    butre Well-Known Member

    in theory, smaller pipe increases exhaust velocity, making higher RPMs possible. in practice it doesn't matter much outside of turbocharged applications or if the pipe is incredibly over/undersized. flow capacity and velocity need to be balanced and none of that back pressure garbage everyone talks about really matters (with an asterisk, look up exhaust scavenging, the kadenacy effect, and the inertial supercharging effect on wikipedia)

    you'll make the most power with no pipe at all, but you'll melt your piston and your ears in short order
    Last edited: Sep 1, 2014
  5. HeadSmess

    HeadSmess Well-Known Member

    the ears, yes..yes you will. the piston, no, no you wont. and as for power...tuned pipes reign supreme on two strokes...always have, always will :)

    but yes, all that nonsense about back pressure is just that. nonsense. except when talking about tuned pipes. but they utilise sound and the fact it consists of high and low pressure zones, not just "backpressure", and arent about to be discussed again. thats what wiki and various other sites are for :)



    i wont link to blairs book because thats just painful for ANYONE to read!
  6. piecepatrol99

    piecepatrol99 Member

    I drilled out the tail pipe to 1/2" diameter but I didn't touch the baffles. They may be getting bypassed as the pipe was gored about. 2" length below the baffles.
    It did help to get the motor running better with the addition of a boost bottle (I love how the bottles are sold and the instructions don't say you need to open the exhaust to match the intake work you've done.) Though it did not add a great amount of volume to the exhaust note.

    I'm still working on other issues. (Like replacing the bike because the fork broke), I'll keeep you updated on my work commuter...