Gas tank shroud

Discussion in 'Motorized Bicycle Welding, Fabrication and Paintin' started by thxcuz, Aug 22, 2015.

  1. thxcuz

    thxcuz Member

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    It's no secret I hate the peanut tank that comes with these kits. I keep thinking about what I can do to make my bike look better. I had an idea about making a fiberglass shroud to go over the tank. I've never done anything like it before so it may look even worse. I don't know.
    If I ever do it I'll post my results.
    I envision a fake tank that fits over the peanut tank. I have no plans yet, just some ideas in my head
     
  2. Davezilla

    Davezilla New Member

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    If you use an epoxy resin like West Systems epoxy it won't eat the foam mold you just made...
    You can buy foam blocks at most hobby stores and sculpt them to any shape you wish, wrap in fiberglass using the epoxy as resin instead of the polyester resin that gets hot and eats the foam. Then acetone will eat out the foam after the fiberglass shape is made without hurting the newly cured glass...

    I've used this process to make a new rear section on my old gsxr 750 when I converted it to a solo seat, but this can be used to for just about any shape using foam, modeling clay, or anything else that's easy to shape then cover with the glass. I've also found that the glass mat works great when a lot of bulk is needed but small sections of cloth that's inter layered works best for really tight compound curves. I also made a new rear fender to replace the bulky original fender on my kz 700. On that one I used the original fender as the mold and covered the inside with a thin coat of Silicone grease, just enough to cover the surface, then put the smaller 2" x 3" squares of cloth inside the fender and built it up about 6 layers thick interlocking these layers of cloth. When it cured I just popped it out of the original fender, trimmed it so there was no part of it that could be seen below the seat level, painted it black and installed it, this way I had my own fender eliminator without cutting up the rare stock fender. It looked totally oem tho because I used the stock fender as a mold.

    Pretty much, if you can think it up, you can do it, and if done right, the amount of sanding and touch up will be minimal before paint and finishing is done. You can use large sections of cloth on most surfaces then cut into small circles or squares to get into or over really tight curves. Cloth and matting can both be used on the same project as well as microspheres which are tiny glass bubbles that can be impregnated into the resin to build up areas where the glass cloth can't get into or to strengthen corners etc...
     
  3. thxcuz

    thxcuz Member

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    Food for thought. Thanks. Would it safely hold gas if I used epoxy resin? That wasn't my initial plan but it could be an option. I was going to make a Styrofoam mold, cover it with blue tape, wax it then use nylon resin & fiberglass sheets from the hardware store. When it was cured I was going to cut it in half and place it over my existing tank. It will be purely decrotive. A working tank would be a whole lot more logical, but logic has never been my thing.
     
  4. Davezilla

    Davezilla New Member

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    This was the way to make small fuel tanks for experimental aircraft and the epoxy resin could withstand the gasoline, but I really can't recommend direct gasoline contact anymore since all the gas we get now has alcohol in it and will degrade the resin probably within about 6 months. The solution would be to line the inside of the tank with an alcohol resistant tank sealer before using if you decide to just make a whole tank in faovr of just making a cooler looking shroud. Also if you plan on making a fiberglass tank, it can be done with the epoxy resin from West Systems but you'll want to make it 6 to 8 layers thick for durability, and of course, use a tank liner like Red Coat to protect the resin from the alcohol. The epoxy resin also remains flexable to a certain extent so it's a lot safer than using poly resins that can crack and form small leaks.
    I repaired a carbon fiber tank for a customer about 4 years ago where the fuel attacked the resin and although it held it's shape, there were areas where the resin was completely gone. I had to re wet the cloth with epoxy resin and use a special tank liner to prevent the fuel from attacking it again. Originally the guy just thought his paint was bubbling until I cut thru a bubble to show him it was leaking right thru the carbon fiber.
    If you do decide to make a fiberglass tank, be sure to line it with something that's been confirmed to be alcohol proof or it wont last, but to re shape an existing tank it'll work just fine.
     
  5. 2door

    2door Moderator
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    Cuz,
    Back in 2011 I built a tank for a bike doing what you have in mind. I covered a steel tank with foam then sanded the foam into the shape I wanted then fiber glassed it. It's a time consuming way to do it but ay least you get the shape and size you want.

    The tank build starts on page 11 > http://motorbicycling.com/showthread.php?t=35675&page=11

    Maybe that will give you some ideas. Good luck.

    Tom
     
  6. Davezilla

    Davezilla New Member

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    Wow... nice tank!!
    That's exactly what I was trying to explain to do, use the steel tank but make a cover to re shape it to something a lot more acceptable looking and yours is definitely a Lot more acceptable looking and there's no direct fuel to fiberglass contact. It's a shame we c ant buy pure gasoline anymore because the alcohol does attack the resins whether you use poly or epoxy resin. I used to repair motorcycle and some automotive tanks with the West System epoxy and fiberglass but those days are long gone...
     
  7. thxcuz

    thxcuz Member

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    Excellent idea 2door! you solved a good portion of the roadblocks i would have come across. Did you need to weld the copper tube into the tank?
     
  8. 2door

    2door Moderator
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    Thanks guys. That tank has held up well. I did put a ding in it when the bike fell over in the grass when I was taking a picture. The horn gouged it where it hit but I was able to repair it.

    Cuz, that piece of brass tubing was there to provide an opening through the foam and access to the bung in the tank when it was finished. It was 1/8" pipe thread simply screwed into the tank where the petcock goes. I did weld a new rear mounting bracket to the tank. You can see it in the finished tank.

    I started with the biggest peanut tank I could find. There might be a better alternative to the foam I used. I chose it because it was readily available and easy to use. When fully cured it is a little softer than some poly foams but with the glass and resin it came out firm enough.

    Let me know if you try this method and if you need any tips or advice.

    Tom
     
  9. Davezilla

    Davezilla New Member

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    I think that type of foam would be the best method since you're covering an existing tank and you want something to follow the contour of the old tank exactly. Then it's optional to leave the foam in there after the glass cures since the foam will also help keep the tank cover lined up and centered on the tank without the need for fasteners of any kind.
    One really nice thing about doing it this way is the ease of repairs if something goes wrong like a tip over it just means cut out the damage, fill the dent with more foam, contour match it, and apply a few more layers of glass and re paint. Keeping the foam in place will also protect the real tank from damage in the event of a crash where the last thing you need is 1/2 gallon of gas all over your bike and yourself.
     
  10. 2door

    2door Moderator
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    The best advice I can offer is to do the foam work when it's warm outside. I did it in the winter and in my garage. The garage is heated but the air temp was just above 60. The cooler the temp the longer it takes the foam to fully cure. A member suggested misting the exposed foam with water to speed the curing time. I don't know why that works but it does.

    Tom
     
  11. Davezilla

    Davezilla New Member

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    The water actually acts as a catalyst for the foam which is the same stuff as that Gorilla glue stuff, but that's also why superglue bonds to skin in seconds... it's not the skin but the moisture that causes it to bond so super fast. Water (or the humidity in the air) acts as a catalyst for most RTV's and gasket sealers as well... Now grab a spray bottle and go try out this new knowledge you posses... I know ya want to...
     
  12. 2door

    2door Moderator
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    Oh, thanks a lot Dave. I just glued the spray bottle to my fingers. Now what'll I do?

    Tom
     
  13. Davezilla

    Davezilla New Member

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    Haha... I never figured what neutralizes the stuff but learned they used the humidity in the air as the catalyst so water will speed up cure times considerably.... you can even start a small fire reaction with superglue by saturating a cotton ball with it. It takes almost a whole tube but it'll get so hot it can actually ignite, the cotton ball just needs to be dry as there's enough humidity most the time to over speed the reaction.
     
  14. Davezilla

    Davezilla New Member

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    This isn't me, but here's a video of somebody starting a fire by saturating a cotton ball with super glue... https://youtu.be/fYFGTs6vQFU
     
  15. 2door

    2door Moderator
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    Fine steel wool and a 9V battery will start a fire too, and it isn't as messy :)

    Tom
     
  16. Davezilla

    Davezilla New Member

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    Yup... that works too...
    Have you ever mixed up too much epoxy or poly resin at one time? That stuff gets crazy hot then starts to explode ... I remember when I was still a young kid about 12 or 13 years old and I was at the airport fixing a cracked wheel pan off a 172 and decided to mix up a slightly bigger batch in a plastic cup so I could brush it on over a larger area... or so I thought... within minutes the cup got too hot to hold onto so I quickly set it down on the hangar floor as not to spill any... next thing I know it started to smoke, then I could hear it start to crack inside the cup, then it started popping off chunks of smoking hot resin... that was kinda scary at first because I didn't know if it was going to catch fire or not, and about that time I realized just why my dad told me to mix the stuff in small batches. I just figured it was because too much might go to waste if I didn't get it all worked into the cloth, but me thinking I could do it quick enough decided to mix up a big batch... then it was also impossible to even try to cover up that mistake since even tho I got it cleaned up and out of the hangar I was afraid it would ignite if I threw the evidence in the trash, and it smelled up half the hangar...
     
  17. 2door

    2door Moderator
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    Yep, I've done it too. And I don't know which smells worse; epoxy resin or polyester. They both reak when overmixed/overheated. Used to do a lot of boat work and had experience with both.

    Tom
     
  18. Davezilla

    Davezilla New Member

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    Yup.. even the slow curing west system epoxy can get really hot really fast if mixed in a larger batch, they say you can mix bigger batches of the epoxy if you can keep it really shallow like less than about 1/2" deep, like mix it then quickly pour into a cookie sheet will allow you time to do your layups without it hyper curing on ya.... that stuff does have a nasty smell too... and it don't just wash off if ya get it on your hands... it'll leave your hands stinking like epoxy for days no matter how many times ya try and wash it off. I found that acetone can get most of it off if ya accidentally get some on ya but it still won't get rid of the lingering smell...
     

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