Issues with dropping out

Discussion in '4-Stroke Engines' started by Allik11, Sep 18, 2015.

  1. Allik11

    Allik11 New Member

    Hi there,
    I have a 49cc, 4-stroke engine bike and I'm having really bad issues with it dropping out. I've had a very good mechanic look it over and mechanically, he's done everything he can to prevent that but I'm still having issues with it. I do let it warm up (about 3-5 minutes) but I still have issue and interestingly, they're towards the end of my ~1 mile ride. I'll come to a stop sign and when I let off the throttle, the engine dies. Warming it up a bit longer does help but I wonder if anyone has any suggestions on what I can go other than wait 10 minutes for it to warm up before I ride it?

  2. msiert

    msiert Member

    Mine did the same thing but after drilling out the bras plug that exposes the fuel mixture screw, I found I was running pretty lean. The best setting I found for that screw was close to 2 full turns out from fully seated. You can also try to adjust the idle screw (the black screw on top of the carburetor) so the engine idles faster. I found that the idle varies depending on the outside temp, I have mine set to idle between 2,400 to 2,600 rpm's.
    Philandra Chambliss likes this.
  3. I second this motion guys running lean.... my Briggs 4 stroke did that until I did a tear down on the car partially and a retune.

    I found two problems problem one being it was running lean if you pull the plug and it's ashy white is very lean.

    The second problem is Briggs carbs have a tendency to loosen the intake bolts on there own.

    Try dismounting your cars from the intake and put lock tite on the bolts.

    After that do a half throttle tune up with the throttle stop bolt set.
    Half idle.

    Since it a 4 stroke, be sure to take a small wiff of the make sure it doesn't reak of gas.

    Inbetween adjustments back your stop screw out and do blips of throttle if the idle hangs it's not set right yet.

    If the carb doesn't respond instantly and drop back to idle repeat until it responds crisp.

    No hang idles or delayed throttles a crisp snap back should be instant.

    Soon as you snap should drop back instantly.

    In addition this is just a base procedure all adjustments should not exceed 2 1/2 turns anything more means it needs rejetting.

    To test overall jetting wind her out to top speed then hit the kill switch once the engines hot...

    Pull the plug shouldn't look white on the tip also the plug should not look extremely clean should be coffee brown but not wet and that covers 2 and 4 stroke engines.
  4. gary55

    gary55 Well-Known Member

    Read the dates 2 yrs. old. Again quit being a idiot.