Vibrations on Schwinn Stingray

Discussion in '2-Stroke Engines' started by McConauwolf, Jul 13, 2016.

  1. McConauwolf

    McConauwolf New Member

    Hello! I'm new to the threads/forums here. I've been building bikes for 1 1/2 years but I'm having a problem with the Schwinn Stingray Choppers.

    They cause serious vibrations after using performance parts on the motor ans bike. It's reaches speeds up to 50-55mph but vibrates around speeds of 25-40 mph to the point where I lose feeling in my feet, butt and hands.

    Rubber on the mounts cause bolts to break or to strip out screw holes. So is there anyway to prevent this. Here's a picture of my custom job. I'm hoping I can solve this problem soon or I may just have to deal with it.

    Current Specs:
    .60mm jet
    High velocity cylinder head
    NT carburetor air filter with direct air flow connect to the carb
    spring tensioner
    36 tooth sprocket
    High performance cdi
    Banana expansion muffler
    V tube motor mount

    Attached Files:

  2. jaguar

    jaguar Well-Known Member

  3. McConauwolf

    McConauwolf New Member

    I'm not gonna just start drilling holes in my crank. If I don't know where it's imbalanced I could just make it worse. That's why i haven't gone to that idea. Already read up on that page
  4. jaguar

    jaguar Well-Known Member

    you don't know where? OK fine. I do.
    the factory piece-mealed the engine together. The balance holes in this crank aren't big enough to counterbalance the heavy piston.
    just drill the holes where I indicate on my page. twaala! balanced engine.
    It's not f***ing rocket science tweety
    2bike, Frankfort MB's and 45u like this.
  5. Steve Best

    Steve Best Well-Known Member

    Whoa, Jag, backoff on the coffee man!
    I can understand you've put the time in to try to understand this stuff, and more importantly, done the experimenting to see that it works. I know it's frustrating to have others who haven't tried anything, put down your experience. I get it man.

    Drilling holes in a crank is scary. It's not irreparable if it doesn't work. You can thread it and plug it or drill on the far side. No worries. One thing is for sure, if you do nothing, nothing will change.

    What can you try until you gather the courage to drill your crank? (I haven't drilled mine yet either!)
    The more rigid the motor is connected to the bike frame, the less vibration you will feel.
    My 48cc just retaught me that. Huge vibrations at certain rpms turned out to be a loose mount.
    On motorcross bikes the engines have headstays to smooth out vibes. Try a mount from frame to your head bolts?

    I like the idea of filling the crankcase opening with Play-Dough (to catch the chips) and drilling the 9.5mm hole straight in, rather than disassemble the whole motor (which would take about an hour of my time!). You can use a "U" shaped magnet at the drill bit to catch chips also.
  6. jaguar

    jaguar Well-Known Member

    I think the only challenge with drilling onto the outer part of the crank wheels is how to steady them.
    A person could start off with a 3/16" carbide drill bit and then if there's still too much vibration use a 3/8" bit. depth should be the same as the crank wheels are thick. location is adjacent to the conrod pin, top of the wheels at TDC.
  7. Steve Best

    Steve Best Well-Known Member

    Carbide drills are normally used for concrete (although specialized tool supply placed may have carbide metal drills).
    Your idea of drilling a 3/16" pilot hole is a good one.
    Buying high quality new HSS (High Speed Steel) drills will assure they are sharp. Cheap drills are a waste of your life.
    Punch a dimple where you want to start. A little cutting oil, penetrating oil or kerosene will help the cut.
    Fast for the small drill bit, slower for the larger one.

    I just thought a vacuum cleaner may help catch the chips. I'd avoid drilling thru to avoid chips falling in.
    My crank is not hardened, would drill easily.

  8. jaguar

    jaguar Well-Known Member