engine runs, but very weak

Discussion in '2-Stroke Engines' started by keylan, Apr 3, 2009.

  1. keylan

    keylan Member

    I picked up a new bike the other day, it needed some new parts (new CDI, fuel line, and spark plug)

    the guy i got it from said it had been sitting for a year or more so fearing the worst i broke down the carb and cleaned it out, though it was not stored with fuel so it was clean

    with a new plug and other parts, the bike fired right up, kidna....the way i have to start it is pedal really fast, drop the clutch (as usual) and then full throttle, pedal for a few more yards until it catches on, then keep the throttle full on until it quits trying to bog out.

    Beyond the bike not idling well, it doesn't run strong, it is sluggish and weak. i adjusted the throttle cable so that it would idle, went for another ride and it over revved like crazy,

    from a half idle and a slow speed, i cannot let the clutch out slowly and accelerate using the gas, i have to pedal fast and let the clutch out

    all in all the performance is crappy, the engine is old, but the compression and spark are strong

    any help would be awesome!


  2. Pablo

    Pablo Motored Bikes Sponsor

    I'm just guessing leaky seals, maybe an air leak.....how is the plug after running it?

    Are you sure the jet is not gummy?
  3. keylan

    keylan Member

    what jet? inside the carb? or in the engine block?

    I have yet to pull the new plug and see how dirty it is.

    do you think that it would be beneficial to pull the top block off of the engine, and clean out that hole, maybe replace that component or the piston or something?

  4. MotorBicycleRacing

    MotorBicycleRacing Well-Known Member

    Trade the carb for a known good one if you have a spare

    Check the exhaust to see if it is plugged up as you said the engine is old

    Look in the exhaust port to check the barrell, rings etc

    The jet is in the carb
    Take the float bowl off

    I have had several jets unscrew themselves lately
    and end up loose in the float bowl

    The engine can still start and idle but have no power
    Last edited: Apr 3, 2009
  5. keylan

    keylan Member

    the gasket around the exhaust is bad, i know that and have already ordered and yet to receive a replacement. I have not pulled off the exhaust tho, but i will now to check for blockage

    I took the float bowl off of the carb and checked the other main components, they are very clean and seem to be working nicely, i blew through the intake and through the other holes i could get a drinking straw around or near, it seems like everything is fine there, but ill swap it out for a test run with my other bike..

    thanks for the info, would love to hear some more suggestions, i am liking what i hear so far.
  6. MotorBicycleRacing

    MotorBicycleRacing Well-Known Member

    Get some gasket material and cut your own as a temporay measure

    I just had a customer who replaced his leaking exhaust gasket on his day
    old engine and he "forgot" to cut the hole for the exhaust.......

    of course the engine would not start and it was a tough one to diagnose

    Moral of the story, don't get stoned before you work on your bike!

    I would only pull the head as a last resort.....
  7. keylan

    keylan Member

    sounds good, ill take a look into the exhaust system before my next ride and depending on what i find i may not ride that bike again until the new gaskets arrive

    thanks again!