Engine Trouble Engine flooded or totally screwed? Loud noises??? (Pics and video included)

Discussion in '2-Stroke Engines' started by sweersz, Aug 21, 2011.

  1. sweersz

    sweersz New Member

    Hey guys. First of all, I've searched relentlessly and have not found a solution to my problem so far regarding my 80cc BGF engine.

    I am in the break-in period with about 100 miles. I run a 16:1 ratio. I've always notice oil spewing out of where the spark plug fits and dripping out of the exhaust from time to time. Nothing went too wrong until yesterday.

    I was full throttle down a hill and all was well. About 2 minutes later, my engine started to struggle and wouldn't respond to the throttle; it just bogged like crazy.

    It progressively got worse within a mile's period; it would bog at low speeds and high speeds; I couldn't even go 20mph. When I would try to, it would bog and backfire (would make a loud boom).

    I checked the exhaust to see if it was clogged, nope! It was fine. I also swapped carburetors to see if it would run better but there was no change; the carb has nothing to do with this issue.

    I have a high performance carb. Did it let too much fuel into the engine? Is my engine flooded? I pulled the plug and head to see what everything looks like and it doesn't look very good (by the way, I have an NGK B6HS plug (.020 gap) and swapped it out after the other one was dirty... now this one is dirty).

    See pics...

    Spark plug:

    Head from above:

    Head from below:

    Inside engine (doesn't look good):

    Excess oil:

    Once I put everything together, I fired up the bike and this time there was a loud popping noise almost as if the exhaust is off. I checked the exhaust gasket and it was fine; all of my gaskets are fine. The bike still bogs and doesn't go anywhere. Here is a video to get a better understanding:


    I am lost. What should I do? Any help would be MUCH appreciated... thanks!!!
    Last edited: Aug 21, 2011

  2. srdavo

    srdavo Active Member

    (let's have a look)

  3. srdavo

    srdavo Active Member

    Going WOT on a downhill is not good. The fact that it starts up & tries to run tells me not too much is wrong with the engine at this point.

    In your video.... the popping I hear, sounds (to me) like your head gasket is leaking. (or blown ? )

    ok..... 16:1 is way too much oil. IMHO

    try 25:1 for a tank or two. & another fresh spark plug (try gapping at .028 )
  4. ddesens

    ddesens Member

    It almost looks like the top of your piston is partially gone. It does sound like you have a bad head gasket or the bottom of your muffler came off.
  5. dodge dude94

    dodge dude94 Member

    I would try to clean everything up, if possible.
    Inspect the head and exhaust gaskets, replace if need be.
    Clean the spark plug really well.

    Also, as ddesens stated, your piston doesn't look very good.
    Clean it, take a picture, and maybe try to scrape off that black stuff.
    Looks just like carbon to me, too much oil, but it may be something worse..
  6. ddesens

    ddesens Member

    16:1 ratio is way too much. Just run 32:1 and take it easy on it for a while.
  7. Al.Fisherman

    Al.Fisherman Active Member

    Yes the head gasket was leaking...Mill the head and install a new gasket coated with
    [​IMG], on both sides. Some use aluminum spray paint.I coat each side twice.
    The piston/spark plug looks like that the carbon was built up due to excessive oil mix. That should scrape off. You didn't mention detonation, so the piston/spark plug should be good, once clean. Trash the junk studs and nuts, go with a grade 8.8, (USS grade 5). Torque the head down to 120 (minimum) to 200 (maximum) INCH POUNDS. I use between 150 and 175. 150 the first build and 175 if I ever have to go into it again. Once I put spray on the gasket, and change hardware, I have NEVER had to remove my head. Been riding since 3/2009
    Last edited: Aug 25, 2011
  8. HeadSmess

    HeadSmess Well-Known Member

    i cant see any sign of leaking on the head...it looks pristine actually. but.

    me personally, despise those heads. the only one ive had leaked instantly and never has sealed. always on the plug side. milling only compounds the problem... removes material from an area thats already deficient... they should have cast more material and machined the plug recess into it. instead, compounded with the fact that theres no cooling in that spot, and that aluminium expands proportionally with heat... you get PICT0264.JPG

    get yourself a new head gasket and head...with the central plug.

    thats just my two cents worth

    never had an issue in this area with the good old 48 with a standard head.
    Last edited: Aug 25, 2011
  9. FelipeCobu

    FelipeCobu Member

    You can flip the head making the spark plug heads to the carb. This way the fresh mix will cool the head, the other way there is the heat from the exhaust plus the heat from the plug.
  10. HeadSmess

    HeadSmess Well-Known Member

    you could do that. id say its the way theyre supposed to be mounted! still doesnt change the fact i got so annoyed with the thing that i melted it down and made an ashtray out of it :)

    and then went back to the trusty reliable 48s :D that 66 was a nightmare...a lemon! a frustrating piece of junk! never again!
  11. FelipeCobu

    FelipeCobu Member

    I'm riding a 70cc but not w/ the "slant head" so far its doing ok, just need a bigger jet after changing CR and polished the ducts.