Carby I bored the jet on a china carb

Discussion in '2-Stroke Engines' started by srdavo, Mar 31, 2007.

  1. srdavo

    srdavo Active Member

    Let it be known, I have an extra carb, or 2, so this wasn't too risky for me.

    Rusty Livesfast now!
    [​IMG]

    After patching Rusty's rear tube, a new plug, some fresh fuel & a good once over on the whole bike...Rusty started easy, but was sorta sluggish after 3/4 throttle. So.... all the talk of boring the main & only jet sounded appealing. I have a set of tiny dremel bits. diamond encrusted...abrasive, but tiny.
    the smallest one..no, I did not use the dremel..went through with gentle twisting. the hole looked big compared to the pin hole in the one not tampered with.
    I put my new jet in Rusty's carb and had a ride. Rusty would run wide open, with some episodes of bogging down.
    Prolly fast enough...but... I raised the needle to the 3rd notch from the top and away we went.........
    At this point, I lost a little bit of take off, but when Rusty wound up...he really screamed! (I swear at one point he screamed "GET OFF ME, YOU FAT B#%*&@!!!!! what are you trying to do...kill both of us?"
    I was really impressed. the stop light by my house was green, so I decided to go to the country mart 1/2 a mile away & use the ATM. When I got there...i pulled the clutch lever & had nothing. I looked down and the clutch arm on my engine was gone. I didn't stop...went back to the house and swapped bikes.....went back to find the clutch arm...no luck.
    but I did find one of Rusty's motormount studs. yup, vibrated one of the engine studs out too.
    Rusty was flying!!! I'll bet I was doing every bit of 35 mph!!
    I know this is not very scientific....no exact sizes, I just got lucky. I'll know more when I get Rusty back together.
     

  2. Guest

    Guest Guest

    Maybe you could list the drill bit size you used so everyone who wants to do this mod will know what/where to buy it.

    I'm glad you took the "chance" with my suggestion....I've done it on other bikes/scooters before with great success.

    :grin:
     
  3. srdavo

    srdavo Active Member

    I don't know the exact size of the bit. There are no markings on them & I don't have a micrometer.

    While you do this, I think it helps if you repeat "If it ain't broke and you mess with it ......." :lol: :lol:
     
  4. azvinnie

    azvinnie Guest

    good story, :grin:
     
  5. jeffspeeder

    jeffspeeder Guest

    so how did u shut it off when u got home? and how did u ride it back if ur motormount was broke?
     
  6. Guest

    Guest Guest

    Anyone else gonna try it? Come on, you know you want to. Even if you really screw it up, you can buy another jet cheap. :)
     
  7. jeffspeeder

    jeffspeeder Guest

    not really but thx for the offer :p
     
  8. Guest

    Guest Guest

    Didn't you drill out something else? Or was that someone else?
     
  9. jeffspeeder

    jeffspeeder Guest

    my bike is for crusin not fot extrem modifications
     
  10. Guest

    Guest Guest

    Drilling the (right) orifice is not and extremem modification, it just helps the bike run better at WOT....
     
  11. jeffspeeder

    jeffspeeder Guest

    well can you tell me how to do it in detail?
     
  12. Guest

    Guest Guest

    See post number one in this thread.
     
  13. Guest

    Guest Guest

    "After patching Rusty's rear tube, a new plug, some fresh fuel & a good once over on the whole bike...Rusty started easy, but was sorta sluggish after 3/4 throttle. So.... all the talk of boring the main & only jet sounded appealing. I have a set of tiny dremel bits. diamond encrusted...abrasive, but tiny.
    the smallest one..no, I did not use the dremel..went through with gentle twisting. the hole looked big compared to the pin hole in the one not tampered with.
    I put my new jet in Rusty's carb and had a ride. Rusty would run wide open, with some episodes of bogging down.
    Prolly fast enough...but... I raised the needle to the 3rd notch from the top and away we went.........
    At this point, I lost a little bit of take off, but when Rusty wound up...he really screamed! "
     
  14. jeffspeeder

    jeffspeeder Guest

    i think ill passs i dont even know whare the jet is can u tell me
     
  15. Guest

    Guest Guest

    It's the brass lookin' "thingy" that the slide needle goes into.

    Don't do it if you aren't familiar with carbs. Just set the needle clip on the second from the bottom notch and ride it.
     
  16. jeffspeeder

    jeffspeeder Guest

    i know carbs just not these little things ill take a look when i get home.
     
  17. Guest

    Guest Guest

    The only carb more simple than these are the ones on model airplane engines....if you know carbs, you should have no problem with these.
     
  18. gone_fishin

    gone_fishin Guest

    easy, now...the "main jet", the one in question, is screwed onto the bottom of the 'pickup', do NOT drill anything else.

    [​IMG]

    ok, the reason i posted is i want to dig a lil deeper before i bore my jet.

    i have the engine running nicely with a white-wire headlight and a slightly reduced plug-gap.

    we've had some cold nights lately, and she runs like the proverbial bat in it. so, a leaner mixture is called for, eh? and, what's too lean? i use a 36:1 real-oil pre-mix. anyway, if i go to a leaner mixture slot, isn't that the exact right reason to bore the jet?

    help me out here, i'm headtripping the details before i make a move, budget matters.
     
  19. srdavo

    srdavo Active Member

    did anyone read the DIY post by sk8freak?
    http://www.motoredbikes.com/viewtopic.php?t=1047

    it gives details on bit sizes etc. I need to get some orifice bits or these wire gauge bits....are they the same thing? then maybe I can get more specific on the stock sized jet and what to bore it out to.

    Augie...if your bike is running good already....why bother? wait & see if I vibrate Rusty to pieces, or blow up my Livefast 48cc. :)
    (also....nice work on the carb pic.. 8) ..photoshop?)
     
  20. gone_fishin

    gone_fishin Guest

    srdavo: paint shop pro.

    and the "why bother" is about top-end only, performance is beyond satisfactory, that's why i'm holding off so far. i may just find a smaller rear sprocket, the low-profile tires justify THAT move anyway.
     
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