50 cc with 66 Speed Carb and billet intake- highly recommend!

Discussion in 'Motorized Bicycle General Discussion' started by Nashville Kat, Aug 3, 2012.

  1. Nashville Kat

    Nashville Kat Active Member

    Apr 20, 2009
    Likes Received:
    Just getting this sorted out after changing jug so I could put on a billet intake and 66 speed carb on my 50cc build-

    I'd done this once before, and found an IMMEDIATE good perfomance increase- but something got inside and scoured that jug in a few miles- so I put the old one back on and rode it a year or two- you may have seen this bike in my video sound comaprison between the 66 and 50. Someone remarked on youtube that the carburetion socked and I knew they were right- it had run sooo much better with the other jug and a standard 50 carb on a billet.


    What I didn't realize was that I could have lately just gotten a new billet that now comes in the same 40 mm spacing the "sleeve carb" did, and still used the older head. Oh well. About the same cost- less work, less risk.

    Below is a picture of the old set-up (totally blue) I don't know why that carb never worked very good- they put it right up against the motor- a good idea, but it was a 50cc carb with a different sort of jet I couldn't change.

    Anyway- without wanting to push it today- I'm finding the 66 Speed carb and billet REALLY DO give me better performance. Better accelleration, and more revs at top end.

    In fact I'm gonna go to a smaller sprocket now too- I have a custom 39 GT alloy sprock bolted to the flip/flop hub, drilled for Disk brake six inner hole pattern,

    but I've got another alloy 34 same as on my 66 build- and I think the motor will handle it- One of these:


    it really starts to close the performance gap now that the 50 is running better with better carburetion- the 66 Speed carb has a bigger float bowl and a bigger jet and makes a difference. And the Huffy cruiser with 700c wheels build is really lightweight and less noisy. And the NT Speed carb is not nearly as pricey as a "performance" carb.

    The carb isn't even very level, but it doesn't seem to be affecting performance


    Attached Files:

    #1 Nashville Kat, Aug 3, 2012
    Last edited: Aug 7, 2012
  2. biknut

    biknut Active Member

    Sep 28, 2010
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    I'm also a fan of the Speed carb. Until recently I was running it on a Flying Horse 48 cc.

    I compared the sizes a NT vs Speed Carb.

    NT carb........ = 13.74 mm
    Speed Carb... = 14.78 mm

    I just changed motors in my bike. I kept the same speed carb.

    IMO the speed carb is a better overal carb than a NT. The NT seems like it has a little better bottom end throttle response, but it's a lot more touchy about 4 stroking on the top end.

    With the Speed carb, the motor starts easier, and idles a lot better. Any 4 stroking is greatly reduced, or eliminated.

    This is my new Flying Horse 80 with Speed carb

    #2 biknut, Aug 3, 2012
    Last edited: Aug 3, 2012

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