The muffler really matters

Discussion in '2-Stroke Engines' started by 210061741, Nov 16, 2009.

  1. 210061741

    210061741 Guest

    I am surprised to find this out but not really.

    I have an SBP Expansion chamber setup.
    I took the muffler off the end to clean it.
    The fiberglass packing was soaked with oil.
    So i took it out and put it all back together.

    Things were ok and it ran good.

    Somehow after a coupla days the pipe that threads into the end of the expansion chamber broke off.

    I got the threads out and attached a pipe fitting to it so i could screw a regular lawn mower muffler to it.

    It is running like ****.

    It used to rev to no end now it feels like i got the stock pipe back on.

    So what is making the big difference here.
    Is it the length of the pipe "stinger" that matters??

    Apparently the exhaust is tunable from the muffler end.

    I just want to get this thing running like it was.

    Anyone have any experience with this????

  2. professor

    professor Active Member

    no experience, but the muff probably is too restrictive. Was it a 1/2 npt one? For a 3 hp lawnmower?
  3. 210061741

    210061741 Guest

    Yes i tried a pancake type muffler.
    With 1/2 Ntp threads.
    Didn't seem very restrictive.
    I Could blow through it easily.

    I replace it now with a long skinny type similar to the size that was on there.
    Still 1/2 inch npt.

    Running better but not as good as it was.
    I will try to drill a smaller size hole through the middle.

    Theres a little plate down in the center of the muff.

    Just really wondering if anyone has had problems using diff. mufflers.
  4. andynogo

    andynogo New Member

    The ideal exhaust for a 2 stroke is the expansion chamber with a stinger on the end and that's it. We add a muffler to quieten it down but by doing that we restrict flow and hurt power. Go with a straight through glass pack for the best flow and some noise reduction- so repack your old muffler and put it back on if you can.
  5. Bent Spoke

    Bent Spoke New Member

    I used a lawnmower muffler on my mini bike, one of those long ones, threaded gas or water pipe is the same thread so I used that for all the exhaust. The center baffle plate can be punched out if your after loud.
  6. 210061741

    210061741 Guest

    My real problem was putting two gaskets under the jug.
    Screwed the intake timing.
    So i pulled them out and WOW shes running super.
    I actually had to back off of the throttle today.
    That usually don't happen.

    I am running the long cylinder shaped muffeler now for lawnmower.
    I did punch out the baffel or little plate in the middle.

    There is no glass in this thing but it's not overly loud.
    Actually runs a little smoother less popping noises just plain vroom vroom.
    Sounds more like a real motor.

    So anyway thanks for helping, I was running myself in circles.

    didn't want to believe that a .050 inch raise of the ports would cause such terrible running.

    but it did.
  7. motorpsycho

    motorpsycho Active Member

    actually, I have the spookytooth exp. chamber on my bike and I added a lawnmower muffler to quiet it down a bit. Mine actually runs better and has more power with the muffler than without it. It sounds like an 80 c.c. dirt bike now rather than a muflled mo-ped engine. After adding the muffler i even gained a little top end speed and it seems like the motor comes on the pipe better and for a longer period than without the muffler.
  8. 210061741

    210061741 Guest

    I agree with tat.
    I rode mine once without the muffler