Yamaha 50 Dirt Bike

Discussion in 'Yamaha' started by Quadrider10, Aug 12, 2014.

  1. Quadrider10

    Quadrider10 Member

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    So im fixing this dirt bike for a customer. he said it wasn't starting. i took it all apart, cleaned carb, got it all back together, and it started rite up. however, it wont rev. it idles perfectly but as soon as i touch the gas, it bogs out unless i rev it slowly. it revs slowly though. in firt gear it run fine, but as soon as i hit second gear, it bogs no matter what. but again, it idles perfect. it got brand new gas, strong spark and a clean air filter. if i lean the air screw, it help with the bog when i first touch the throttle, but it way too lean. Any Ideas? its a 4 poke BTW.
     
  2. harley1-5

    harley1-5 Active Member

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    have you checked valve adjustment?
     
  3. Quadrider10

    Quadrider10 Member

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    No. The thing is brand new. And there is NO noise coming from the engine (tap, etc)
     
  4. Herpderplol

    Herpderplol BRRAAAAAAAAAPP

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    must be the parking brake....

    :D
     
  5. harley1-5

    harley1-5 Active Member

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    valves may be too tight
     
    benharcombe1985 likes this.
  6. Quadrider10

    Quadrider10 Member

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    ahhh damn. before this it was running fine he said. then they stored it for a long period of time and it started to do this
     
  7. Quadrider10

    Quadrider10 Member

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    Huh. I just tried to adjust the needle, and there is no adjustment on it. I doubt it had to have a jet changed? It's bone stock everything.
     
  8. harley1-5

    harley1-5 Active Member

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    maybe you missed something in the carb?I had 1 do the same did you check float level?
     
  9. Quadrider10

    Quadrider10 Member

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    float is fine. it doesn't run out of gas, and it doesn't leak. ill take it apart again and check everything over again.
     
  10. Quadrider10

    Quadrider10 Member

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    Ok so I cleaned it out as best I could. However, now it's not bogging much, but it's running poorly. Like its way lean. I took the air box off and filter and tried like that and it was bogging even more which seems to me to be running lean. Ideas?
     
  11. blasterkid1998

    blasterkid1998 Member

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    Air leak? Is the carb adjustments set to factory specs?
     
  12. 03blasterboy

    03blasterboy Member

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    Is it a ttr 50? If I remember right the mixture screw was 1 1/4.
     
  13. speedyslyder

    speedyslyder 2 STROKES RULE Technician

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    yeah what is it yamaha 50 what?
    compression test?
    fuel flowing freely from tank to carb?
     
  14. Quadrider10

    Quadrider10 Member

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    Everything is bone stock. The only thing changed was the air screw and that was by me. Its pretty far in. I don't think it's leaking. I can check however. If I'm not mistaken, an air leak or a lean mixture on a 4 stroke isn't bad rite? And yes it's a ttr50
     
  15. speedyslyder

    speedyslyder 2 STROKES RULE Technician

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    i had a ttr90 and the carb was wicked hard to get to the air screw,they pit it on inside closest to the motor, and when i bought it that was one of the problems,plus stale gas and dirty carb :)
    Did you check plug gap?
    i bought a kids quad and the friggin thing was almost touching :(
     
  16. Quadrider10

    Quadrider10 Member

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    Yup ckecked gap. Ok so running it with the choke on, it runs damn near perfect. Which means it's lean. Gas is fresh. And no air leaks.
     
  17. Blaaster

    Blaaster Moderator Staff Member Technician Forum Supporter

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    Is the air filter damaged and lettin in excess air?

    Could you have overlooked some crud in a jet?

    A lean mix or an air leak is bad for any engine, it creates excessive heat.
     
  18. speedyslyder

    speedyslyder 2 STROKES RULE Technician

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    i had same problem with the ttr90 ran great with choke on and not with it off,it was def a carb related problem,and i fiddled with carb for pointless hours i was able to fix problem lol...some people just replaced the whole carb to solve there issue but i did not o_O
     
  19. Quadrider10

    Quadrider10 Member

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    Hmmm. Nope air box is all good and sealed. Maybe I should just buy a bigger jet? I cleaned the carb 3 times now. I know 100% that it's clean.
     
  20. Quadrider10

    Quadrider10 Member

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    Well did some research and from factory, these things run lean. So I'm just going to buy 2 jets 1 and 2 sizes up.
     

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