49cc 2 stroke only runs without end cap

Discussion in '2-Stroke Engines' started by Foolwithadui, Sep 28, 2016.

  1. Foolwithadui

    Foolwithadui Guest

    Hello all, sorry to bother you, but I have a strange problem with my bike. I recently purchased a 2 stroke bicycle from some guy on Craigslist, who claimed it was newish. I'm assuming it's stolen and had sh*t sh*t kicked out of it, because Craigslist. Butt problem is that after running fairly perfectly for a week or so, one morning I went to ride to class and it just wouldn't start. After class I went and looked at everything I could think of (that's not much, I'm not super experienced with smaller engines) head gasket flawless, clutch fine, carb fine, air filter not clogged, little fuel shut off thing and tubes and filter all fine, magneto fine and power wire not shorting, kill switch cdi and spark plug fine (but not great. Stock, and wouldn't hurt to change the plug) but when I had just about ran out of ideas, someone said to try it without the exhaust. I didn't trust no exhaust, so I just took that little cap at the end off, and lo and behold it runs! There's nothing like blocking the exhaust or anything though, so why would it not work like this? I would much prefer the exhaust back on, as I prefer to try and keep at least a somewhat low profile. TL:DR. Runs without exhaust silencer, but not with it, and I'd prefer it with it.
     

  2. crassius

    crassius Well-Known Member

    my first thought would be that petcock was left on and motor got full of fuel - too much smoke when it runs is an indication of this

    the end cap does nothing but redirect the exhaust back up into the body so that it goes thru holes in baffle plates to get back out the small pipe sticking down - you might stick a piece of coat hanger iwire up there to see if it is clear
     
  3. Arty

    Arty Active Member

    Can you blow through the pipe? If you feel resistance it might be getting clogged.
     
  4. jaguar

    jaguar Well-Known Member

    I don't believe it absolutely wouldn't run without the end cap. I think that's an exagerration.
    Running poorly I could believe but a little extra backpressure won't kill an engine.
     
  5. crassius

    crassius Well-Known Member

    spoken like a man that has never had someone shove a potato up his exhaust
     
  6. jaguar

    jaguar Well-Known Member

    yeah and that's the only way his story is correct, if there is a potato in the final stinger.
     
  7. zippinaround

    zippinaround Active Member

    or simply blocked with a mix of steel shavings and baked 2-stroke oil from break in , i found a ton of shavings in a brand new stock exhaust i took apart i mean about 100g's or so they dont clean out the shavings from drilling all the holes sometimes it seems and if you dont clean em the 16:1 mixture jams it fairly good .
    maybe not the case but just my 2 cents
     
  8. crassius

    crassius Well-Known Member

    I once found melted plastic wrap inside one after it ran a while.
     
    zippinaround likes this.
  9. zippinaround

    zippinaround Active Member

    honestly i wouldnt be surprised if someone found a spud in there.!!!
     
  10. gary55

    gary55 Active Member

    Mmmmmm baked potatos
     
  11. Foolwithadui

    Foolwithadui Guest

    thank you Crassius, after blowing through the pipe, and deciding to straighten out a wire hanger, and wiggle it around in there, I determined that there was quite a bit of black. It runs considerably better now, but just to be safe I ordered a new exhaust. Just a plain ol' standard one though, no fancy racing expansion chamber or nothing.
     
  12. Foolwithadui

    Foolwithadui Guest

    Thank you, Sir
     
  13. Foolwithadui

    Foolwithadui Guest

    Lol, you've clearly never melted a cat before, I've had a clogged 3rd cat completely immobilize a Ford Explorer before, I just didn't consider the possibility of one of these exhausts getting clogged, seeing as there was no cat
     
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