4 stroke Engine Vibrates at low speeds and will not stay started.

Discussion in '4-Stroke Engines' started by Thomas Williams, Apr 5, 2013.

  1. Thomas Williams

    Thomas Williams New Member

    I have a 4 stroke Huasheng kit .
    It was running fine but on the way home the engine started vibrating at low speeds
    when I would get to a light I would have to keep given it gas to keep it started.
    If it died I could get it to start but only by given it gas while pull starting it.

    When I would start off there would be little power , when I got the MB up to say 8-10MPH the power kicks in and the vibrating stops
    What could it be wrong?

    Please help as I'm a newbie and know nothing about these kits, any and all help would be so helpful.
    Last edited: Apr 6, 2013

  2. darwin

    darwin Well-Known Member

    Sounds like your idle is set too low. What kind of kit is this? Rear rack, in frame or?
  3. dougsr.874

    dougsr.874 Active Member

    Had the same problem with a new HS engine....The carb. used to have an adj. screw, but the newer version has that adj. blanked out with a brass plug...the brass plug can be drilled out, and underneath is an adj. screw....open that screw untill engine works right.....Uncle Sam strikes again.
  4. Thomas Williams

    Thomas Williams New Member

    I don't thank it's the Idle nor the Carb.
    It was running fine and then just like a switch went off I slowed down and it started vibrating real bad and the engine staled

    to get it restarted and keep it stay started at the light I had to either give it a lot of gas or turn the idle up so high (why to high) you had to hold the brakes real tight to keep it from taken off.
    Once the light changed it would take off real slow vibrating real bad until you got up to 8-10MPH, then the vibration stops and the power comes back, run great good power and no vibrating until you slow down the slow you go the more the vibrating, loss of power and the more it tried to stall
  5. MotorBicycleRacing

    MotorBicycleRacing Well-Known Member

    What kit do You have?
    What gearbox?
    Where did you buy it from?

    Your problem is your centrifugal clutch but until I know what gearbox
    it's hard to give advice.
  6. Thomas Williams

    Thomas Williams New Member

    it's the hoot gearbox as far what kit all I can tell you is the 4 stroke Huasheng about 1-2 years old I got the used bike with the kit on it and has no other markings

  7. MotorBicycleRacing

    MotorBicycleRacing Well-Known Member

    The "hoot" gearbox is an abused term.
    The only hoot gearbox is the one that looks like a figure 8 on it's side and has gears.

    A pocket bike gearbox has either a single or double chain inside.

    Either way take your gearbox apart, you could have a broken spring or
    something else broke on the centrifugal clutch.
  8. Samdallas214

    Samdallas214 Member

    I went to Tom's on monday and got his MB fixed today
    it was the clutch spring all 3 broke,
    the clutch was not in the best of shape, so we just replaced the clutch
    Bikeberry had the new clutch to us super fast cost $5.00 extra but ordered it on Monday had it by Wednesday
    so no more walking for Tom
    Last edited: Apr 10, 2013
  9. zwebx

    zwebx Member

    i have had a similar problem with the clutch springs... but it happend more than once im not sure whats doing it either i dont let the clutch get too hot or anything
  10. Samdallas214

    Samdallas214 Member

    I have not had it happen to me again. but I did just replace the entire clutch for $15.00 off eBay
    I find out you can use a $10.-$20.00 eBay 2 stroke clutch .
    the part that bolts on the engine might not be the same but the clutch shoes are the same so what I did was take the shoes and the spring off the 2 stroke clutch and put them on the 4 stroke clutch part that attaches to the engine .
    Once you take the spring off you can unscrew the shoes and put them on the 4 stroke part work great and it's less then 1/2 the cost of a 4 stroke clutch, and about the same as the 3 springs them self
  11. Big Red

    Big Red Active Member

    When was the last time you adjusted the valves? Something to look at anyway. If the engine is two years and NEVER had the valves adjusted, I'd say it's about time. They do loosen some after a while. But it could also be a clogged low speed jet. I just had about the same thing happen to a customer build cause I was running it without a fuel filter for a minute for testing. It don't take much to clog a carb. So adjust the valves and clean out the cab. I think you'll find it runs again.
    Big Red.
    Last edited: May 27, 2013