dellorto phbg 19mm carb from treatland tuning woes

Discussion in 'High Performance Bicycle Engine Tips and Motorized' started by graydog8josh, Feb 27, 2014.

  1. graydog8josh

    graydog8josh New Member

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    I got the phbg 19mm carb from treat and I have no idea how to start tuning it.
    it says its got a starter jet
    an idle jet and a main jet, needles atomizer and all this just to tune it.

    All i have that will fit it now is the main jets 60 to 85

    to get a roundabout even tune comparable to my rt carb that i have on there right now with a 66 jet what should i do.

    Btw im running 36:1 with a mildly ported reeded and tuned motor it runs just okay with the 66 jet and the rt carb (34mph) but it was running super rough when i slapped on the new carb and i couldnt get a good idea of what was happening.
     
  2. graydog8josh

    graydog8josh New Member

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    Really what im looking for is some to tell me
    " hey im at sea level, i have a reeded motor with an expansion chamber. I have the phbg carb and i am using..
    main jet: xx size
    idle jet xx size
    needle : xx
    clip position: xx
    atomizer: xx
     
  3. mech_engineer

    mech_engineer New Member

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    40 to 45 idle and main 66 to 86, depends on your engine needs
     
  4. Goat Herder

    Goat Herder Gutter Rider

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    60 to 85 is way too lean for me over here at 6000 ft. On the little Morini I beleive 90 or 92? Pretty sure about that... With the stock atomizer of course and idle jet.. not too sure? 50 to 55 would be my guess for idle jet size. Been a long time since I had to give my carby some thought. We have folks here at sea level. Supprised nobody has piped in?
     
  5. Goat Herder

    Goat Herder Gutter Rider

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    I think mine came stock with a 262 AU atomizer because I had to go three atomizers sizes the other direction on mine, and know it was a W9 needle. I run a 49cc two stroke Morini. If that helps?
     
    #5 Goat Herder, Mar 4, 2014
    Last edited: Mar 4, 2014
  6. Huffydavidson

    Huffydavidson STREETRACER/MANUFACTURER

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    I have two PHBG carbys ones a 19.5 and the others 21mm and DUDE your back in class . There is so many variants is not just altitude and atmosphere but how your engine setup is configured.
    So I'm pretty good at it now, however it has taken quite some time to get to the point of fine tuning. So if you want to drop me an email and maybe swap phone numbers I'll share with you what I've got I've got several internet pages that I could forward to you and things like that and help you the best I can but it's just too much to do here.
     
    javy mcdees likes this.
  7. Moto

    Moto Member

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    Im at sea level: 21mm phbg
    main: 86
    idle: 39???
    starter: whatever came stock - I dont use the choke as its never much colder than 45 here.
     
    javy mcdees likes this.
  8. graydog8josh

    graydog8josh New Member

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    right now im at 74 main
    40 idle
    clip at bottom
    and it is a little boggy right off idle the middle is pretty good and full is boggy at hi rpm it is boggy too
     
  9. rogergendron1

    rogergendron1 New Member

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    The dellorto phbg is sweet but a newbs nightmare lol

    You can get idle jets idle jet emusion tubes main jets and main jet emusion tubes new needles with differant tappers and even differant cutaways for the slide! !!

    Now the stock emusion tube for the main is probably good and the idle jet is probably good too and the needle is probably the right tapper and your slide cutaway will worl just fine

    so that leaves us with the idle jet and the main jet amd slide needle posistion


    i like to mark on the throttle an arrow then on the pther side i mark wot then i mark closed then half way then 1/4 then 3/4 throttle position on the twist throttle . This way when i look down i can see an arrow pointing to a marker and the marker would indicate the jet the carb is on at that throttle posistion . Exe i twist the thrpttel and take off then it starts to bog so i look down and i see the arrow pointing just over the half way mark . That would let me know i am on the needle jet and its position or shape need to be changed! !!
     
  10. rogergendron1

    rogergendron1 New Member

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    Or or i get a bit of four stroking and look down to see i am pointing at the 3/4 marker dead on . That would tell me the main jet is too big and the needle should go down one clip

    you realy need some markings on your throttle to see the jets and to tune them during test rides!

    but put it this way if the bike even starts with the carb on it then your close already!
     
  11. graydog8josh

    graydog8josh New Member

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    Thanks roger i think important too rich at full throttle but instead of sputtering its diving likeits getting no fuel its weird. would it do that if it was 6 sizes too big it was doing it at 82 and its still doing it at 74
     
  12. graydog8josh

    graydog8josh New Member

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    just so people can believe ive spent time and money on jetting, lol. heres some of my jets, they're all over the house.

    jets from 60's
    5 stock jets(im guessing their all 70 jets i never use nt stock jetting unless its on a new engine with the nt carb completely unmodified and breaking in)
    70's 72 74 76 77
    and an 80 and 84 jet

    also , plugs. i have never used the stock ones but i collect them when i sell people good ngk plugs to run their bike on
     

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    #12 graydog8josh, May 30, 2014
    Last edited: May 30, 2014
  13. Moto

    Moto Member

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    Now running an 84 but 83 might be better
     
  14. ldrancer

    ldrancer New Member

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    hold it full throttle for a bit. and see where its at. sometimes it would take me nearly 2 miles of riding around to see what its doing. maybe your 3/4 is too rich. if its boggy at around 1/4 throttle, when you get going, then your rich. if at takeoff, as you rip the throttle back the bike doesnt even move in the yard. pilot. mixture screw. or maybe the atomizer.
     
  15. Huffydavidson

    Huffydavidson STREETRACER/MANUFACTURER

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    Moped Army has some real good info on tuning the PHBG carbys. Also do a Google you'll be reading and learning a lot!!! They are COUNTLESS ways to get the same resuits!!!!
     
    javy mcdees likes this.
  16. graydog8josh

    graydog8josh New Member

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    yeah thanks hd. thats what im trying to use to tune by and this is where im at:

    top speed 36mph

    idle jet 40
    main jet 85
    needle in richest setting
    idle mixture screw halfway in/out

    about the same top speed as my rt carb :-\ with less responsiveness and much bigger jets. the 70's jets were way too lean at wot it was cutting out
     
  17. ldrancer

    ldrancer New Member

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    i figured that stuff out on my own. they wont really help, .. unless you got a moped. i would think a bike wth a motor on its a moped.

    but for me to find any problems with up top tuning, i had to cruise my bike, well, floor it with it just running badly, on me, for 2 miles. at least. i have a cht gauge also. the worse part is when its actually running if its running hot. if its not hitting then its usually not raising temperatures either. unless you got an air hole, leak, or something too. going on. after 2 miles or so, a needle problem, would usually disappear then the main jet would run for me showing how its tuned. usually every main jet will hit, but unless their extremely rich. or lean, maybe. yea. but that was my trick to getting the main jet to come u and show up whats going on.

    im not remembering how i figured where the main jet was or the needle was in this place now, thou. and by the way oh who cares about that other place. im giving tips right here.

    hes at a forum why you gotta mention another one.
     
  18. ldrancer

    ldrancer New Member

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    and also being helped.

    I'll remember how the finding the main jet or needle is your problem deal. In aminute.
     
  19. Huffydavidson

    Huffydavidson STREETRACER/MANUFACTURER

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    I changed slides up from 30 to a 40 in one bike and 50 in the other BIG difference in throttle response. Gona order a 60 just to have in my "tuning drawer"
     
  20. ldrancer

    ldrancer New Member

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    cutting out? probably rich. keep on holding it. you mean, raw dogged cutting and running pretty erratically and hesitatingly, like? thats lean. but, just boooorrrr is rich. if you hold it itll usually for me, pop and backfire. holding it wide open. edit: then you'll know its rich.
     
    #20 ldrancer, Jun 3, 2014
    Last edited: Jun 3, 2014

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