Tank petcock

Discussion in 'Motorized Bicycle Welding, Fabrication and Paintin' started by Toothy, Aug 15, 2014.

  1. Toothy

    Toothy New Member

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    Hello guys,
    I’ve just bought this tank and it looks like it will fit my bike well. Only problem is that it’s a moped vertical mounted type. The petcock is high in the horizontal position. Without being a welder what would you suggest? I want to cap it and install a new fitting lower down so that I use all the gas. What you think?

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    #1 Toothy, Aug 15, 2014
    Last edited: Aug 15, 2014
  2. Going2Hell

    Going2Hell Member

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    If you absolutely want or need it to sit flat, I have no idea.

    If you could tilt it backwards even a little bit, you should be getting most of the fuel.

    Really, without a welder; there is not much you can do about it. Do you have the ability braze? I would suggest solder but that bond is not strong enough for this type of work. Without either of these abilities, I would suggest tilting the tank unless you are going for a rat-rod/Frankenstein look.

    Cap the OG petcock with a bolt and a bunch of epoxy, cleanly though; don't get messy. Drill a hole in the location you want it, big enough to fit a brass 1/4" hose end from the plumbing section of a Lowe's or Home Depot. Yet more epoxy, and you should be home free!
     
  3. SchwinnStingray

    SchwinnStingray New Member

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    I, if you really could not weld, would just cap off the pet cock thread where it is and buy a chinese $2.87 pet cock, the ones that fit the plastic pocket bike tank, they have a thread insitu that uses two nuts to lock in with a rubber o ring on the outside to seal.
    Drill a 10mm hole, stuff around for two hours trying to get the nut on the inside to screw to the pet cock from the outside and your laughing.
    Obviously, if you choose this route, you will need to position the pet cock as close to the filler as possible.
     
  4. wret

    wret Member

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    You could use a Yamaha type petcock. You'd only need to tap the screw holes or use use sheet metal screws with a good grip.

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  5. curtisfox

    curtisfox Well-Known Member

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    One could carefully cut the petcock out and solder it on the bottom then put a patch over the hole..................Curt

    A full tank will never blow just fill with water if using a torch. Just use a hole saw cut it out drill a small hole on the bottom solder it there. Then cut a new patch cover the oridgional hole.
     
  6. Going2Hell

    Going2Hell Member

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    If you cut out the petcock and try to solder it back somewhere else without any other reinforcement or prep, it WILL fail! Solder is not strong enough to cope with the stresses a petcock mount is subjected to.
     
  7. curtisfox

    curtisfox Well-Known Member

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    Not true if you do it right. All the old gas tanks from the old briggs engines and others were soldered on. Like i said use a 3/4 or 1" hole saw cut the petcock out and then drill a small hole the size of the petcock hole it will give you double thickness.
    Prep yes one has to really clean and use acid,and pretint the parts before swet soldering...........Curt
     
  8. Going2Hell

    Going2Hell Member

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    Okay, that fixes the petcock issue even though I believe the old Briggs petcocks were Brazed; not soldered? I am only 30 and see the old tanks less and less often anymore.

    Curtisfox, this method done with this much redundancy will work well and last for a long time to come! I take back my remarks and fully support your process...

    (Informational purposes for Toothy should he proceed)

    You are talking about Lead/Tin solder or Silver? Silver is much stronger but requires a higher temp to get to flow.

    To patch where the petcock was, you will need a patch at least 1/4" larger than the hole on all sides?

    Dilute Muriatic Acid for a surface prep in lieu of a flux?
     
  9. Toothy

    Toothy New Member

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    Thanks for all the great info. This solution seems to be the easiest though. I mean just cut a hole and drill the addition screw holes right? I would like to avoid brazing and messing around with solder. I’m assuming this would be mounted on the bottom of the tank with the tubes (filters?) in the vertical position. The one seems pretty long...how does it work?
     
  10. Toothy

    Toothy New Member

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    Sounds fiddly but also a great idea. I’ve done a search and found several that may be what you are describing. Would you mind posting a pic of an example……Thanks again guys!

    Like this.....just add a nut on the inside?

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    #10 Toothy, Aug 15, 2014
    Last edited: Aug 15, 2014
  11. Going2Hell

    Going2Hell Member

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    The Yamaha petcock would be pretty easy since you can find it almost anywhere...

    To do this you would create three holes in your tank. For the gasket to work, you need to tighten the screws more than the un reinforced sheet metal will allow. You just need to use a lot of epoxy where it mates to the tank as well as screws.

    This is just the way I see it going in my mind. There is probably a better way still, just throwing it out there.
     
  12. Toothy

    Toothy New Member

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    Thanks...weighing my options.
     
  13. wret

    wret Member

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    The longer tube is the main and shorter one is reserve. You can cut the longer one to whatever length suits your volume level and concept of "reserve".

    If you have a way to position the nut inside the tank the other one would be simpler.
     
  14. Toothy

    Toothy New Member

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    I just need to find the right unit.....one hole is better than three.
     
  15. SchwinnStingray

    SchwinnStingray New Member

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    Yes, as you said, the nut it screws into is captive in the plastic tank so therefor missing.
    You may need to get an extra nut if you go this way.
     
    #15 SchwinnStingray, Aug 16, 2014
    Last edited: Aug 16, 2014
  16. Toothy

    Toothy New Member

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    Ahh! I get what your saying. Just hope it seals well. Thanks!
     
  17. Jumpa

    Jumpa New Member

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    I would lop it off with a dremel or hacksaw which one is the closest one to me.
    Sand it and apply some JB weld "the poor mans welder"
    some folks on here will say NO do not use JB weld it will fail bla bla bla All I Know is the stuff works miracles for me

    I had a stud snap off one of my gas tanks leaving a hole about the size of .50 cal. round black powder ball ball I used the JB weld as a test and 4 years later it i still holding ' If it was under any kind of pressure of course Id say "NOWAY" to the JB weld however it is very little less than the amount in a coke bottle The stuff worked for me

    The key to making it work well is clean, clean ,clean, the area it's to be applied to, then I let it sit for 5 times the recommended curing time. I then sanded it, applied another application "because I sanded it too much" repeat then paint.

    Then just drill and tap a new hole Use a bit of teflon tape perhaps double dope it with some rector seal you should be good to go. Some on here will tell you JB weld isn't made for petro products bla bla bla all I'm telling you is what worked for me well for only 4 years so far .
    P.S. one thing Id do a little different is install the new ole first the plug the existing one to prevent the jarring and banging of the JB welded area not that it w8ld matter if done properly I've even had this nosey kid drop my bike and its still holding to this day !!
     
  18. Going2Hell

    Going2Hell Member

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    I personally love JB Weld... I used it for my first time almost 25 years ago. I Had to re-attach a side view mirror to my 64 Chevy Pickup. 25 years later, the mirror is still very much attached to the truck.

    I don't really care what anyone says about it, I just figure the people complaining about it don't know how or where to use it.

    If you look up JB on this forum, there are some amazing things JB had done for a lot of people.
     
  19. SchwinnStingray

    SchwinnStingray New Member

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    [​IMG]

    If you zoom in the photo on the right hand side of the tank you can see mine.
    Due to rust repairs, I welded the extra nut in but I don't see much problem if the nut is lose on the inside, when you screw the pet cock in you then run the outside nut up to the tank which has an o ring to seal.
     
  20. Toothy

    Toothy New Member

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    Thanks......looks good. Same tank?
     

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