Ready to throw the keihin away

Discussion in 'Motorized Bicycle Trouble Shooting' started by Ichigo, Jul 4, 2017.

  1. Ichigo

    Ichigo New Member

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    Here's what I got. This thing never ran right from day 1 and I'm tired of it. Do I spend the money on a jet kit or is there a carb I can buy that would be as big as the keihin that will actually work? I finally have my low end rpm smooth and powerful, but when cracking wide open after that it just sputters all over the place. Smooths out when I just maintain speed. Sometimes the idle shoots wAayyyy up after pulling in the clutch. I'm tired of messing with it and really need some advise here.

    66 cc gasbike GT8.

    Thanks guys.
     
  2. crassius

    crassius Well-Known Member

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    I like the original NT clone that has the chinese chars on it.
     
  3. Kletus

    Kletus Member

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    Is it a GT 80 with a reed valve?
     
  4. mike carter 2

    mike carter 2 Member

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    20170624_201055.jpg i have the gt 80 kit,ive been running for over 1300 miles.it took some tuning on the carb over the entire time ive ridden it.i first put a chamber from a 1979 rm suziki rm 60,then did some port work on the jug and cases,at the same time i ported my piston,reed valves will not run rite without piston porting.the very first thing you need to do is trash the flexable exaust the kit came with.its to resrictive,it chokes the engine way,way down,get a good chamber first,then port your piston,or buy one.then start tuning the carb.my bike is pretty heavy,and i weigh around 200 and it will do over 40
     
  5. Ichigo

    Ichigo New Member

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    Yes.
     
  6. Ichigo

    Ichigo New Member

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    That sounds like more work than I want to do. I'm beginning to think it's just a too rich. I'll see if I can get a video of it.
     
  7. mike carter 2

    mike carter 2 Member

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    sorry ,i should have said,im still running the stock jet
     
  8. mike carter 2

    mike carter 2 Member

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    how old is the kit,how many tanks of fuel have you run through it,it absolutly will not run rite till its broken in,5 or 6 tanks at least.even then it will run better after more and more tanks are run through it,it gives the rings time to seat.and like i said,good chamber and a ported piston are a must,the rest is for fun
     
  9. Kletus

    Kletus Member

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    I couldn't get my GT-80 to run at high RPM's. I jetted the carb from # 65-75 with no success. It ran the best with the factory jetting of #71 but only at low rpms. Finally I removed the reed valve and tried to blow through it. I really had to make an effort to get any air through it. The reeds seem to thick and are down on the seats with way to much tension. I've done a lot of work on chainsaw's and I've never seen reeds set up this tight. I removed this engine and installed a 79cc predator. I may get back to it one day---after i forget the BS this engine gave me. Next time I'll buy from DAX.
     
  10. mike carter 2

    mike carter 2 Member

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    makes me want to upgrade my reeds,i know a site that sells carbon fiber ones.im ordering some soon
     
  11. mike carter 2

    mike carter 2 Member

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    i wont buy another one,i dont care for the reviews ive seen,i realy didnt like fact that the piston wasent ported,the exaust was trash,the jug was ported some but could have been better.ill buy from zeda from now on.but thats not to say i havent had over 1300 fun,trouble free miles out of it
     
  12. Ichigo

    Ichigo New Member

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    I am on about my 5th tank, have the needle all the way lean, and have a blueberry expansion chamber with muffler. Sorry for the quality, but you can hear how it runs. After reading some of this, maybe I should just get a different carb. Any suggestions?
     
  13. mike carter 2

    mike carter 2 Member

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    give me a min
     
  14. mike carter 2

    mike carter 2 Member

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    find a site called shiny red tuneing keihin carberator jetting,thats where i learn about tuneing my carb,it has any and all info that you need to tune your carb.i would start with the needle in the middle position,and the mixture screw at 2.5 turns from bottom out..to lean it out turn screw in,to make ritcher,turn out. my carb ,the mix screw is about 1 3/4 turns out,needle i think one up from there,thats just what i have to offer from my experance with the same kit,and i still tune on my carb every now and then.one more thing,my bike is very sinsative to the fuel mix,i mix at 40 to 1.any thing lower than that pulls my top end and tork down
     
    #14 mike carter 2, Jul 4, 2017
    Last edited: Jul 4, 2017

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