Did I just ruin my engine?

Discussion in '2-Stroke Engines' started by mcassMB6, Jul 4, 2008.

  1. mcassMB6

    mcassMB6 Member

    I COMPLETELY removed the stock baffle inside my muffler. I thought this was a good idea. I cut out the entire length of it.

    QUESTION #1: If I continue to ride like this...what will happen?

    QUESTION #2: Should I get a replacement stock muffler, or weld on an expansion chamber I've found (Kawasaki KX 65)


  2. Put the cap back on then you'll have a loud exhaust. Engine needs back pressure but I don't think it will ruin anything. I would get some steel wool. Now did you completely gut out the innards? Or did you simply cut the tube off? Gutting out the innards I don't know how that would affect back pressure.
    And many members have experimented with expansion chambers here. Search for expansion chamber and you'll get some hits.
  3. mcassMB6

    mcassMB6 Member

    I've ridden it already like this. Nice and loud. I snipped the baffle as far back behind the "crimp" as I could. What came out was a 3" long pipe with tiny holes and a crimp.
    The cap is back on.

    The reason I asked is because somebody on this site said that my engine would basically explode...and why did I do that blah blah blah.

    Just checking.
  4. I believe even with the baffle gone, with the cap on you have plenty of back pressure. If you want to quiet it down a bit I would do as LF says and get some steel wool and pack in there.
  5. fastboy9

    fastboy9 Member

    I did it and my bike was fine, but your exhaust will probably explode, thats what happened to me! The can exploded away from the header pipe at the weld, it happened to somebody else too. Backpressure will be fine, if there isnt enough back pressure then the engine will run lean, you can tell if its lean by looking at your spark plug. You can see if its too lean or too rich by comparing your plug to these ones: http://www.dansmc.com/Spark_Plugs/Spark_Plugs_catalog.html

    If it is running too lean then all you need to do is richen your mixture in your carb. After cutting my baffle out it didnt lean out at all. Just ride your bike for about half a mile or so, then remove your spark plug and have a look if its too lean.

    But if you can put on a KX65 expansion chamber on it then go for it!!! If you have an "80cc" engine then that expansion chamber is almost tuned perfectly for your engine as the true displacement is 67cc, just put that on! about 30% of a two strokes potential performance is in the exhaust pipe design, and the stock ones are only there to keep the noise down a bit. So if you've cut the baffle out then it wont make it quiet at all so you might as well just go for the dirt bike pipe.

  6. mcassMB6

    mcassMB6 Member

    Yeah, I would say I've only got 100 miles on the engine at this point, so I am still running a 16:1 ratio mix. So I think it's safe to say that I'm not running too lean. After a few more tanks, I may switch and run at 20:1.

    However, my brother has been running that rich for at least 1500 miles. Hmmm...maybe some thoughts for a post later on.
  7. softride

    softride Member

    did i just ruin my engine

    one thing to think about is that with lots of police forces having differing views on motored bikes they may just lump your nice and loud in with every one else who causes a noise problem
    these bikes need to be under the Radar so that the interest can be built up and seen as a good social alternative not another trouble making hobby, I know loud is cool sometimes I have dual 5" mufflers on my race car but we all need to promote the friendly side of this activity,also as mentioned two strokes are very susceptable to exhaust length and shape .
    Good Luck
  8. GasKicker

    GasKicker Member

    Whoooooh! DON'T USE STEEL WOOL! It rusts, and crumbles, and Pieces of the steel wool will get sucked back into your combustion chamber and your engine WILL be ruined.
    If you use anything use a copperized pot scrubber. It's less succeptible to corrosion and if anything gets pulled back into the chamber it will be softer than the surrounding metal and cause little if any damage.
    The best idea would have been a far less radical mod.
  9. sparky

    sparky Active Member

    Nice tip! Thanks.
  10. eljefino

    eljefino Member

    There's two kinds of "lean", one is how much oil to gas you have, and the other is how much oil+gas (fuel) to air you're running. The latter is what exhaust pipe tuning messes with.

    Ironically, and confusingly, both kinds of lean can be diagnosed via spark plug... rich oil will be an oily plug, lean fuel/air a powdery brown one.
  11. sparky

    sparky Active Member

    It's the powdery brown color that you're looking for. I've always considered it tan, but yea... wet & black or dry & white is what's really bad.