Carby Micro drill bits for jetting NT carb?

Discussion in '2-Stroke Engines' started by RadicalxEdward, Oct 29, 2014.

  1. I can't afford a new carb with all the other repairs i need to make, so I figured I'd work on the NT carb i have. I think it needs a new jet (something smaller i think) but instead of buying a bunch of jets and wasting money on those i don't use, I figured I'd drill it myself. I just want to make sure i'm getting the right size bits. Would this set be the correct sizes?

    If anyone has any tips about a good brand/seller to buy a set from that works well without breaking the bank i'd love to hear from them. These are the kinds of things where you get what you pay for and cheap is going to be cheap. I don't mind spending a little bit more to save myself a huge headache from crappy bits. All the ones I'm finding are either more than the cost of a new carb, or cheap to the point of not being usable.
    Last edited: Oct 29, 2014

  2. dougsr.874

    dougsr.874 Active Member

    An LP or Natural gas serviceman usually has a set of orifice bits in his tool assortment....These bits are by their nature a precision tool....they're NOT going to be cheap..
  3. crassius

    crassius Well-Known Member

    don't know how steady your hands are, but I consider it a good month if I only break one of the tiny little things - buy cheap & in bulk : )
  4. butre

    butre Well-Known Member

    I don't know about making them smaller but I've used a set of welding torch cleaning files (about $4 from home depot) to make them bigger.

    for smaller the only way to do it is to solder the hole shut and stick a tiny drill bit through it
  5. jaguar

    jaguar Well-Known Member

  6. troyg

    troyg Member

    Harbor Freight sells an assortment of micro bits they call "micro burrs".They come in plastic packs of 10, from so small I can barely see them (finer than human hair) to around .022-.024 for the biggest.
  7. fattirejack

    fattirejack Member

    You can get a wire gauge drill bit tip cleaner set for under 10 dollars at most welding supply houses. Set includes 12 drill bits and drill holder
  8. Thanks for the tips guys. From what I can tell there is just no getting around the delicasy of these bits. They're just too tiny for there to be major differences is brands (Which all seem to be pretty much the same) I was also going to get a micrometer to make sure the bits are the right sizes.

    Before I order this stuff I thought to check ebay. My budget for this stuff is about $26 (including shipping) But I noticed there are main jet sets (60,65,70,75,80 sizes) for less as well as SHA carb clones for less than that.



    Would either of these make a better purchase in your guys opinions? Does the SHA clone have a fuel mix screw? I think my bike is running too lean. Should i stick with trying to tune the NT carb or try to get a different carb? I will try to get a better one down the line but i have to make this bike viable before i can go spending $50-80 on a carb.
  9. jaguar

    jaguar Well-Known Member

  10. dirtwarrior

    dirtwarrior Member

  11. jaguar

    jaguar Well-Known Member

    those that you refer to step from one size to another in .1mm increments. You need at least .05mm increments. (.5, .55, .6, .65, .7, etc)
  12. Jaguar is there an email or something where I can contact you directly with a couple questions?
  13. jaguar

    jaguar Well-Known Member

    Just send me a private message or find my email on my site
  14. Tried to email you and it got bounced back saying you've exceeded your mailbox quota. Tried to PM you and got a similar error. so here's what i sent.


    This is RadicalxEdward from I read through much of your site and I've decided to try to put some money into a new carburetor after getting a bit more information. especially your advice.

    The two popular choices (CNS and SHA) are both cheaper on eBay then other sites and that puts them in my price range. There's the SHA 15:15 clone that seems to be the one you recommend, and there's also the CNS carb. It appears the SHA clone is a set it and forget it type affair aside from the main jet. The CNS has more adjustability. I'm leaning toward the CNS for that reason (along with a set of jets). I like the set it and forget it idea but i know it won't work that easily (nothing does for me) and I want to be able to do as much tweaking as possible if it doesn't work great out of the box. So basically I'm just looking for your advice. You've responded to my threads when i've had questions and you seem quite knowledgable about all of this stuff. This will all be in leu of those micro drill bits we spoke about.

    Also according to my research I'm at nearly sea level. The highest point in the city is <300' above sea level. Just in case that makes any difference to your recommendation.

    Thank you for taking the time to read this and help me out. I appreciate it.

    Also according to my research I'm at nearly sea level. The highest point in the city is <300' above sea level. Just in case that makes any difference to your recommendation.
  15. Your site has a load of helpful stuff. If I can get this bike to run reliably and perform decently (right now it barely runs and when it does it doesn't go over about 10-15mph max) then I can justify putting more money into it. I'd love to one day build a bike that takes advantage everything you talk about on your site.
  16. jaguar

    jaguar Well-Known Member

    the SHA was fairly good for me when I lived at 8000ft but terrible when I moved to the coast. So its lack of adjustability makes it one I don't really recommend. I hope you've read my report on the Mikuni carb. I have no experience with the CNS.
  17. Is this the right size Mikuni? It says 18.84 ID which should fit the stock intake manifold shouldn't it?

    I notice it's got a different style clamp. not sure how much of an issue that would be. could probably make it work.
    Last edited: Oct 31, 2014
  18. jaguar

    jaguar Well-Known Member

    It doesnt have a clamp, it is bolt on. If its mounting holes were spaced the same then you would lose all intake tract length which is bad for low rpm power. Also it is a 4 stroke carburetor.
  19. Looks like i'll stick with the CNS carb. But there seem to be 3 versions of it. Do you know what the major differences are between those?
  20. Since I'm getting off topic re a new carb, i've started a thread specifically for that in the carb section. I think jaguar has given sufficient answers to the micro drill bit question.