speed carby and NT carby Question

Discussion in 'Performance Mods' started by adrian101, Aug 20, 2012.

  1. adrian101

    adrian101 Member

    Is there a difference between the speed carby and NT stock carby slide and needle.. Reason i ask is because i can't find the speed carby slide kit anywhere, i can only find the NT stock carby slide kit.

  2. crassius

    crassius Well-Known Member

    I've seen a lot of Speed, NT, and WH carbs - never seen a significant diff except that the needle, needle jet, and main jet are often a bit different - slides so far have all been the same.

    I use WH carbs because the Speeds & NTs often have jets that are too large for the H2 engines we usually use.
  3. MotorBicycleRacing

    MotorBicycleRacing Well-Known Member

    I have seen a lot of NT and so called speed carbs.

    The slide on a speed carb (The one with the shut off on the side )
    Is a little bigger in diameter and
    will Not fit into a NT carb.

    what does WH stand for?

    have you ever put a speed carb slide into an NT?

    The needles are different sizes.
  4. Purple Haze

    Purple Haze Active Member

    The slide is slightly larger on the "speed" carb, and they have a plastic shutoff valve, that is the only difference I can tell visually. On the other hand, the "speed" carb seems to perform better, at least on my 49cc. It idles much better at lower rpm, has more low-end torque, and gets better fuel mileage. Suprisingly, it doesn't seem to have any more top-end power, which is what is expected from a larger bore-size. Also, these carbs seem to be getting hard to find.
  5. crassius

    crassius Well-Known Member

    Haven't seen the speed carb with the shutoff in quite a while - the 3 low-price carbs we see now are all copies of each other except for the jetting that comes installed. The large jet NTs won't even get a motor started at any needle setting. The last 3 or 4 hundred kits have had the WH carbs, and even those often need the needle dropped right down to the leanest setting to get a decent idle. I may have to play with jet sizes soon to clean up a lot of 4-stroking we're getting lately.
  6. adrian101

    adrian101 Member

    Yeah i pulled apart both my Speed carby and NT carby to check the differences. the bore is a little larger in the speed carby. the NT carb slide wobbles around in it.

    Thou the jet from the speed carb is larger then the nt carb jet but fits and works awesome in the NT carb. I notice a big difference just by switching jets :cool:
  7. birdmannn101

    birdmannn101 Member

    If you were going to replace the old NT carb on your 2 stroke, which one would you go with another NT, WH or speed carb? Would you have a link to it?
  8. crassius

    crassius Well-Known Member

    Carbs are hard to work with for me right now. We're not getting anything with a **** number on the jets and jet sizes seem to get larger & larger each batch. This last few months, I've had to drop the needle to the leanest position just to get a decent idle, and they are 4-stroking a lot.

    Had a bike from last year to work on yesterday, and it 2-stroked fine & flew down a level road. Wouldn't climb hills well tho. Looked at needle & it was in middle, so lifted it one notch richer and all was good again. So refreshing to see one that acted right!

    I believe that all the cheap carbs are OK if they're jetted right, but how to get one that's right, I don't know yet.

    If I get time, I'll order a set of numbered jets and see what is needed.
  9. adrian101

    adrian101 Member

    I like the speed carb, there are a number of different carbs, i have used the speed carb and Stock NT carb only. I can't say it is the best as i haven't used all the different types of carbs available but the speed carb does increase performance.

    link to the speed carb: http://www.pistonbikes.com/New-NT-Carburetor-for-Motorized-Bicycle-p/epfc15b.htm
  10. Huotalicus

    Huotalicus Member

  11. Huotalicus

    Huotalicus Member

    yes there is a good difference dear friend the barre is bigger and the fuel inlet is also larger and adjustable.... Great lil upgrade go for it...i got it on mine with better cdi and 3 prong plug ...still breaking in but goes great soo smooth at 35 40 ....its my 3rd tank so after this one il get to 50