Bike was running good, but now not...possibly caused by being left in rain...?

Discussion in '2-Stroke Engines' started by Sg187, Sep 6, 2014.

  1. Sg187

    Sg187 New Member

    Hi all, first post on the forum. Hello and thank you for listening/reading.

    Here's the deal. 66/80cc kit from

    Got it installed and had it running good for 3 days. Then suddenly it started to lose power, missfire, backfire on deceleration, and now it's doing all that and running WAY more rough - to the point where it shakes my arms and legs pretty bad, and won't idle - just dies if I stop giving it gas, and I really can't ride it because it just screams something is very wrong.

    This could be a coincidence, or not - but this started occurring around the same time that the bike was accidentally left out in heavy rain. I can't say whether it was exactly after being left in the rain or not...but thought it should definitely be mentioned.

    I'm at a loss. So far this is what I've tried:

    - Removed, drained and cleaned carb, checked for proper functioning the best I know how
    - Removed and cleaned air filter
    - Replaced spark plug
    - Drained and replaced fuel/oil mix (which is at a 20:1 ratio for break-in period as per the seller at
    - Replaced fuel filter
    - Removed chain gear cover - nothing obviously out of whack from the outside view
    - Removed the cover to the left of chain gear cover - the electrical area with magnet (not sure what all that's called) - nothing obviously out of whack, but I don't know anything about what's in there
    - Removed clutch cover - There is a build-up of fuzzy looking stuff along with the normal grease on the back side of the cover. Yeah, it just looks like fine fuzz, about the color of the air filter element - a dark grey, almost black.

    I think that's it...along with a great deal of internet research.

    Any ideas??? I greatly appreciate it if you followed this far.

    Thank you,

    Last edited: Sep 6, 2014

  2. Slogger

    Slogger Member

    I'm not any sort of expert on these Happy timers, but if the rain had anything to do with it maybe you should check your wiring connections from the CDI unit, water might be causing a short to ground intermittently, this could cause misfires and backfiring.
    Then I'd look at the float level, which can also cause poor running, flooding, backfiring and whatnot.
    Hope you sort it out!
    Good luck.
  3. jaguar

    jaguar Well-Known Member

    clean the metal of the stator coil frame where the mounting screws heads touch it. That metal to metal connection is part of the ignition circuits ground loop. If that don't fix it then buy another CDI, preferably the Jaguar CDI.
  4. crassius

    crassius Well-Known Member

    I wouldn't buy a CDI of any kind to fix a bad coil ??!!??
  5. HeadSmess

    HeadSmess Well-Known Member


    good advice... hang on to your money for a little bit longer ;)

    back to the issue.

    disconnect the kill switch.

    try it then.

    otherwise, use the search function to find out info on checking the CDI and the coil... its been repeated so often i see no need to repeat it again ;)

    if you happened to use the white wire as part of the kill switch circuit... try the search function first ;)
  6. jaguar

    jaguar Well-Known Member

    Slogger likes this.
  7. KCvale

    KCvale Motorized Bicycle Vendor

    Sounds more combustion related, like a loose intake pipe or carb, maybe a clogged exhaust pipe running 20:1, 25:1 is better then go to 32:1, but just in case it is electrical I have step by step test for electrical as well.
  8. Fabian

    Fabian Well-Known Member

    It sounds like something is very wrong.

    If the bike has been sitting out in the rain, the first thing i would do is disconnect the kill switch from the ignition system. When they get water inside the contacts, you can have all sorts of strange misfire/backfire problems, because when the engine fires intermittently, the exhaust system fills up with unburnt fuel, then when the engine does fire, the fuel ignites inside the exhaust system and """BANG""; sometimes a f*#king big "BANG" that blows out the end of the muffler.

    If that solution doesn't work, i would use the method described by Jaguar and Slogger.