where can I find the answer on here

Discussion in 'Motorized Bicycle General Discussion' started by pwrobleski, Jun 1, 2010.

  1. pwrobleski

    pwrobleski New Member

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    So I'm working all the bugs out and it seems I am running good. Until I hit 20-22 mph, then the engines sounds different and pulls like crap. Noise changes from a whahhhhhhh to a Brrrrrrrrrrrr. Then I can feel the motor pull, let go, pull, then let go. I probably have around 50-60 miles on it. i would know exactly but my digital bike speedo keeps resetting itself, grrrrrrrrr.lol. usflg
     
  2. Mac

    Mac New Member

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    PW,
    I'm taking a guess here, your runnin a 2 stroke. Sounds like the old "too big of a jet syndrome". Something to try(once), get on a long stretch of flat road, wind it up until it "4 strokes" Brrrrrrrr as you put it, basically falling off on power/bogging etc.. ANYWAY, when it's doing the bog, shut the gas petcock OFF, keep the throttle on, If in about 10 seconds, it starts to pull again for a consistent time(a few seconds), the Jet is too big. there is a procedure to make the jet the right size, Norm helped me with this, I believe the thread is in "Norms 2 stroke repair center" 4 stroking at WOT

    Mac
     
  3. Alajoyn

    Alajoyn New Member

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    Whats with the digital bike speedo. Ain't powering it via the magneto on the engine are ya now? Hmmmm.

    Robert
     
  4. Cabinfever1977

    Cabinfever1977 New Member

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    All the digital speedos get reset from interference from the cdi mag killswitch and bike frame and cables. It will work better if you mount the speedo 3 or 4 inches in front of the bike handle bars on a plastic mount of some sort. Or you can move the cdi and kill switch toward the rear of the bike.
    Some people also replace there sparkplug wire and boot and that works too.
     
  5. GearNut

    GearNut Active Member

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    If it is a Chinese in frame 2-stroke, the engine will not run perfectly until after the break in period. That takes about 2 to 3 gallons of fuel and 500 to 700 miles.
    What oil ratio are you mixing your fuel at? 16:1 to 20:1 is the general accepted ratio for break in. I prefer 25:1 myself.
    What color is the spark plug at the electrodes, the part inside the engine?
    It should be a flaky looking brown to black, but not wet looking, when a heavy break in fuel to oil ratio is used and you have a good air to fuel ratio. If it is black and wet looking then you are running a bit rich on the air to fuel ratio, which I suspect you are. Check it and get back with us. Armed with more info we can help you out better.
     
  6. pwrobleski

    pwrobleski New Member

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    Hey thanks for the info, I just checked the spark plug and it's a milky brown. And yes it's a 2-stroke chinese in frame motor. So far my fuel mixture has been 25:1. I was told it would run better after it broke in. I just didn;t figure it would do what it's doin...lol. I weigh about 175, my bike with motor and gas probably weighs around 50-60 lbs. I have the stock 44 tooth rear sproket on the bike. So was hoping to atleast be able to cruise at around 30. I tried putting a 36 th sproket on but my motor didn't like it muchlaff
     
  7. pwrobleski

    pwrobleski New Member

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    hey thanks Mac, i will give that a try tomorrow when it's light out.

    .flg.
     
  8. pwrobleski

    pwrobleski New Member

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    Hey thanks Cabinfever, I was leaning toward the vibrations and a little about the kill switch. I never thought to just move it forward, that seems like a simple fix. I was just at the bike shop today and seen one of those mounts you mentioned.flg.
     
  9. GearNut

    GearNut Active Member

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    If your spark plug is a milky brown then you are good to go for an engine that is broken in.
    Since yours is still in the break in mileage, I would like to see it more like a dark chocolate brown. This slightly rich fuel/ air ratio insures that there is a little bit extra oil getting to the engine's internals and it burns a bit cooler than a leaner ratio.
    The too big of a jet syndrome leans towards a very rich fuel/ air ratio, which would make the spark plug black in color. This also causes "4 stroking". This may still be possible in your case and will only show up during 3/4 to full throttle operation.
    I now suspect that you may have a bad spark plug or spark plug wire. Either of these problems will cause poor operation at higher engine speeds. With all the previous questions and checks, we have pretty much ruled out carburetor jetting and oil ratio problems.
    Oh yeah I almost forgot, are you using the stock plug in wire connectors between the engine wires and CDI wires? Those are notorious for being a problem. If so, suspect them before a bad plug or plug wire. Solder them and use electrical tape, or for the best job use heat shrink tubing, to seal and insulate them.
     
    #9 GearNut, Jun 2, 2010
    Last edited: Jun 2, 2010
  10. pwrobleski

    pwrobleski New Member

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    Hey thanks GearNut, I will go ahead and just replace it. I will have it in a few days so I will get back with the progress.flg.
     
  11. pwrobleski

    pwrobleski New Member

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    Today I picked up some solder, gonna jump on that tonight after work. Just to see how much of a difference it would make I cut & twisted them back together w/electrical tape. It got up to speed pretty quick without the 4 stroke sound. But with me cuttting and gutting out my exhaust it sounded like a chainsaw going down the road...lol. So in short my motor never got the chance to warm up to run right. In that short little run it seemed to not do it as bad on my 8 block run. But not sure if I would be able to notice since the motor wasn't warmed up. Tomorrow I will be able to braze the end back on my exhaust just to tone it down a bit. I might end up having to buy a new exhaust, which stinks. I had to cut and bend this one so it would fit because I changed the angle of the mount..flg.
     
  12. pwrobleski

    pwrobleski New Member

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    So I have a 80/66cc 2 stroke china motor, with less than 60 miles on it. I took the advice and soldered my wires together instead of using the plug in connectors. I changed the stock plug to a iridium, also upgradedthe wire and cap. Since the upgrade in wire and cap, which was a better insulated wire and a waterproof cap my speedo works great- Thanks guys. So after I finished I took it for another test run. My mb climbed good all the way to 24 mph. Then I hit a wall again and it 4 stroked back down to 18.9. I could not break that wall, I even drove it around the block a few times to warm it up but no luck. I know it's not the exhaust because my stock muffler was gutted. So I thought maybe the air filter was fudged. I pulled back in the garage and pulled it off and back out I went. Same thing at 18mph, So here I am back to square one. I can say I feel the difference with the electrical fix, it revs better. With me climbing up to 24mph then backing down to 18.9 Could it be my carb? When I hit 18 I still have 1/4 throttle left but when I turn it struggles and bogs down sound like a 4 stroke and all power is gone just putt putt putt..... .kick2.
     
  13. Maxvision

    Maxvision New Member

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    Hrmm...I have no problem with my speedo. Even when I'm hitting 45 mph....xct2

    redriderdisc.jpg
     
    #13 Maxvision, Jun 5, 2010
    Last edited: Jun 5, 2010
  14. CoastalCruiser

    CoastalCruiser New Member

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    Give it time to break in. Don't blow it up rushing!
     
  15. GearNut

    GearNut Active Member

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    ^^^ Listen to what CoastalCruiser said.^^^
    Alot of these engines run like crap until they are broken in. You have all ready addressed the typical problems that they have right out of the factory.
     
  16. pwrobleski

    pwrobleski New Member

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    Alright.....lol :) Thanks for everyones advice, i will put it to good use. I will break it in fully before I do any mods to make it run faster. .flg.
     
  17. GearNut

    GearNut Active Member

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    You have chosen wisely.
     
  18. pwrobleski

    pwrobleski New Member

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    So to add to this thread my breaking in period is going slow.....lol. the other day i was riding to work on my mb at around 14-18mph. I am changing it up and not staying at a constant speed. I was almost to work so i decided to open it up just to see if i could make it past 19mph. And to my surprise it climbed to 30mph. At that speed it was so smooth, way better than at 19.But in that 20 seconds all my ?'s were answered. At that speed all the vibrations were gone, handlebars and in the seat. The motor sounded like it should, I hope it gets back to running like that after break in. This went on for about 20seconds then one of the exhaust allen screws came out. Wow... it was LOUD...lol. I backed off the throttle and made it to the maintance shop at my job and replaced the allen cap screw. So on my way back home that night it was back to running like crap when i hit around 19mph and could not go faster.

    So my ? is this normal to have a short burst of speed and not be able to do it again while breaking in a china 80/66cc motor?
     
    #18 pwrobleski, Jun 18, 2010
    Last edited: Jun 18, 2010
  19. GearNut

    GearNut Active Member

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