Petcock Thread

Discussion in '4-Stroke Engines' started by rananthan3, Jun 30, 2015.

  1. rananthan3

    rananthan3 New Member

    The threading on the below frame for the petcock is not correct. I insert the bolt and it just rotates without catching the threads.

    I tried to hammer the petcock in and used yellow teflon tape to prevent leaks but this a workaround. anyone know an alternative besides using a tap?

    pics below

    with teflon.jpg without teflon.jpg

  2. KCvale

    KCvale Motorized Bicycle Vendor

    Just get a petcock that actually fits the frame.
  3. rananthan3

    rananthan3 New Member

    I appreciate your wisdom. I will keep hunting for it. The one I have is a millimeter too wide.
  4. KCvale

    KCvale Motorized Bicycle Vendor

    Do you have an assortment of spare bolts?

    All you need to do is find one that fits perfect into the tank hole and take that to a hardware store to find a petcock with the same threads.

    You can get a fitting, like maybe a 90 fitting that will go into the tank and also fit your petcock at the other end so take the petcock with you too.

    I don't know what you have local but around here I have stores that carry things like that and they are staffed by usually smart cooperative people.
  5. Arty

    Arty Active Member

    If I remember correctly, the hole is 1/8 inch NPT size.
  6. MotorBicycleRacing

    MotorBicycleRacing Well-Known Member

    The stock kit petcock thread is 10 mm 1.0 which fits my frame.
    However the threaded fitting on yours looks different.

    Those frames may be NPT thread now which is tapered.
    NPT thread petcocks are very common.
  7. rananthan3

    rananthan3 New Member

    Thanks guys for the help. I called gas bike dot net and they said the frame was not NPT threaded and that their petcocks are the correct size. He suggested I clean the threads out with a wire brush. I'm pretty sure its defective. The way it's in there now is pretty snug. I found a bolt that fits so I'll try the 90 degree fitting. If the gas doesn't leak, I don't need to do anything :grin5: Has anyone lost a crotch on these things?
  8. Timbone

    Timbone Active Member

    1/8 FIP for the Skyhawk Frame.
  9. rananthan3

    rananthan3 New Member

  10. MotorBicycleRacing

    MotorBicycleRacing Well-Known Member

    Do you have a Skyhawk frame?

    What petcock did you use and where did you get it from?

    Some "Skyhawk" frames use the stock 10 mm 1.0 thread for the fuel valve.
    I know this because that is what threads into the frame I have.
  11. KCvale

    KCvale Motorized Bicycle Vendor

    Nationwide Access (gasbike, kings) has outsourced fake GT2 Grubee frames from another vendor but keeping the registered name for promotion, which is why not just Grubee Inc won't sell to them, but neither will China Gas, the distributer of everything Skyhawk.

    The big tell between frames is the presence of back V-brake bosses.
    If you don't have them, it's a knock-off.

    New GT2 frames are near production that will take a 3" wide wheel and a rear disc.
    In short a bike like this Fito that will take a 2 or 4 stroke engine or even electric shifter.



    Pretty much an MB like those without the kit peanut tank.
    Last edited: Jul 2, 2015
  12. rananthan3

    rananthan3 New Member

    I have two petcocks:

    Neither of those are NPT (tapered). The frame I have is the GT 2 A frame from gas bike. We are not sure whether the threading on the bike is tapered or not. I am having trouble finding a 1/8" NPT petcock. Once I do, I will know for sure.

    Thanks again for your support.
  13. rananthan3

    rananthan3 New Member

    I tried all of the following below. Plastic may work but that one was too big. The second one I have in there now just not threaded correctly. The last one doesn't have a valve but is 1/8" NPT and did not work. The conclusion is that the threads were not created properly or damaged somehow. The stock valves from gas bike should have fit correctly.

    valves.jpg final.jpg

    Attached Files:

  14. rananthan3

    rananthan3 New Member

    I went on my first ride around the block. Very fun! Gas still leaks around the edges of the petcock but it is minimal. I may try adding another layer of tape. I forgot to torque one of the bolts on the 4 G transmission. It got lodged in between the belt and the 100T pulley but no damage or injuries!