Engine Trouble Chinese Engine trouble

Discussion in '2-Stroke Engines' started by CM523, Mar 8, 2014.

  1. CM523

    CM523 New Member

    Hi, new guy here.

    I recently acquired a prebuilt bike from a guy on Craigslist. It's been working fine for a couple of weeks now. I was on my way to work yesterday and the engine choked up and stalled. It wasn't quick either, it lost power to the ground but still ran. No amount of throttle would get it back up and going. Messing with the choke made it perk back up a bit but not for more than a second or two.

    I took off the exhaust and checked it for blockage, because a new drip had shown up. It was black like used engine oil, and it hadn't been there before. I removed the air filter and carb and dumped out any excess fuel, looked for dirt or blockages. There were none. I even dribbled a bit of 2cycle into the head in case I screwed up the mixture and the cylinder dried up. After I got it back together I pedaled it to start it, and it got going, but it was smoking hard, likely the extra oil I added into the cylinder. It seemed to run fine until I got to the end of my street and it started dying out again.

    I'm at a loss here, as I'm not that mechanically inclined. I will admit that when I gassed up yesterday I pour it straight in and then added the oil, but there wasn't a lot of room because I was a dummy and topped off. Could even a bit of pure gas cause the engine to start seizing? Or is this something else like a clutch needing adjustment?

    Remember: I'm new to these engines, treat me as such. Thanks for any and all help.

  2. MotorBicycleRacing

    MotorBicycleRacing Well-Known Member

    Do NOT mix the oil with the gas in the bikes tank.
    Mix in a separate container.

    What oil to gas mix are you using?

    The oil may have dropped to the bottom of your tank and filled the carb float with mainly oil
    which will not combust.

    Remove the float bowl off the bottom of your carb and flush it out with mixed gas.

    Where are you located in the US?
  3. CM523

    CM523 New Member

    That might explain it. It sure feels like it isn't combusting right, and the fuel in the line looks pretty blue. If I emptied the tank into a container and then mixed it would that work? Or is this batch of fuel ruined?

    I've been using a 6.4oz bottle of oil for every tank of gas. The tank is a bit more than a half gallon I think.

    I'm in florida.
  4. CM523

    CM523 New Member

    That appears to have solved the issue. I emptied my tank into a gas can and shook the stuffing out of it and put it back in. The fuel in the line doesn't look really blue anymore, and it runs. It's smoking, but it died down during my test ride. I expected that anyway from the amount of oil that made it in (now that I understand what's happening.) It runs very rough, and a little jerky. Should this stop as the oil burns off? Or do I need to open the whole thing up and clean it up?
  5. CM523

    CM523 New Member

    I've been riding it without the stalling, but it's very rough. Sounds awful. Halfway home I pulled the clutch and the engine surged so hard I thought it was about to explode. The kill switch didn't even worked so I let go of the clutch and let it roll to a stop. Scared me half to death. When riding it sputters a lot, and the only thing that stops the sputtering is giving it just a bit more throttle, but then it sorta "catches up" and starts sputtering again.

    There is also a hill in my neighborhood that it could clear without issue normally. It almost stalled out going up it this time. I really hope I didn't irreparably break this thing. I just got it :(.
  6. butre

    butre Well-Known Member

    that sounds like vacuum leak to me, check that your carb is installed all the way
  7. CM523

    CM523 New Member

    It was a couple of leaks actually. One where the exhaust mounts to the block, and one where the intake mounts to the block. Runs great now. Now if I can avoid being a bonehead anymore maybe I can keep this thing running. Thanks for your help guys.