Quick And Easy Power With Simple Muffler Mod

Discussion in '2-Stroke Engines' started by cobrafreak, Jan 9, 2011.

  1. cobrafreak

    cobrafreak New Member

    This is probably old hat to most of you, but it could be helpful to some.

    I have been looking for a bit more run ability and power and I found a simple,quick and cheap way to do it. I made a drawing:


    I reasoned that the hole coming out of the engine is much larger that the one going out of the muffler, thus creating a restriction. I measured the existing exhaust hole at 13/16". I simply drilled another 13/16" hole next to it. WOW! Significant power increase, especially low end power. The response is better. Climbing up hills is no problem at all. The exhaust flow coming out of the engine now is so much greater that it was necessary to move the carb needle valve clip all the way down to the bottom so the needle is at the uppermost position. After all, the fuel being burned is what is making the power. More fuel burning, more power. If you don't move the clip down/needle valve up you wont make any gains. The sound is louder, but not too loud. Much louder if you remove the entire bottom of the muffler off. I measured it at idle at 90 - 92 db. Putting around the neighborhood slow is not too loud. Getting on it is a little louder. loud enough for me to wear ear plugs because I don't like too much noise. You make the call on this. I think the trade-off is well worth it. If you don't like it you can always weld the hole back up or put a bolt and nut in it to plug it up.
    Last edited by a moderator: Jan 10, 2011

  2. gothicguy64

    gothicguy64 Member


    here in oz we have zbox.com.au
    he sells an shows ideads to help
    if u cut ur internals an drill the outlet tube then refit u get 10-40 % more power an a few db ..
    zbox has pics toooo

  3. DuctTapedGoat

    DuctTapedGoat Active Member

    I actually cut the baffle off of mine about 4-5 inches, when you take out the tip of mine, the baffle comes out with it.

    But you can't do that with the catalytic exhausts (as easily), as the baffle is not attached to the tip.

    That would work in a catylitic exhaust, I'm going to have to pick on up now just to compare the baffle chop with the extra port by the tip.
  4. cobrafreak

    cobrafreak New Member

    Yes, mine is a catalytic muffler. When you take the end cap out it just come out with the single tube.
  5. DuctTapedGoat

    DuctTapedGoat Active Member

    That's awesome - and I really like that you can plug it with washers nuts and bolts if you don't like it, or made too large a port.

    Though whenever I pick one up to compare with the baffle mod, I'm going to go full on into it and find a way to easily remove the internals of the catalytic.
  6. Rogwarf

    Rogwarf New Member

    A true tuned pipe is really the way to go. But the first thing I definitely do this to these kits is gut the stock mufflers to an extent. I think stock that they are definitely to restricted.
  7. DuctTapedGoat

    DuctTapedGoat Active Member

    How do you go about gutting the catalytic exhaust? It'd be nice to have a tip before I go in blindly.
  8. Rogwarf

    Rogwarf New Member

    I have not come across a cat yet my self. I shorten the baffle on the end cap then drill two holes in the end cap. I found it is more pleasant and quite to run the pipe to the back of the bike less oil to deal with on the bike after that. Been using the SBP tuned pipe.

    That would be nice to see some up close pictures of these cats?
  9. DuctTapedGoat

    DuctTapedGoat Active Member

    I double checked the rules and didn't see anything saying I couldn't link to another forum. If there is a rule about it, feel free to remove these links, or ask me to and I will.

    There's quite a few pics on two different styled cats, which is why I just linked over. Plus, credit where credits due and I don't have source references.

    The black one is the one I have had experience with, the chromed one I haven't seen before.

    Last edited: Jan 10, 2011
  10. rj1967

    rj1967 Member

    First I took cap completely off muffler and it did run smoother and got louder but I didn't see any difference in power. Then drilled 2 holes in end cap. Quieter but still no difference. Did I miss something or does just vary from motor to motor?
  11. rj1967

    rj1967 Member

    OK so I went back and reset my needle to allow more gas. Definitely notice a difference. Not a HUGE difference but does have little more go power. ThAnks for the tip.