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Author Topic: 1980 SR250 Build, get Excited  (Read 5730 times)

Offline advCo

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Re: 1980 SR250 Build, get Excited
« Reply #10 on: Nov 07, 2016, 15:38:17 »
Brazing when done properly does not melt the parent metal and therefore reduces the likelihood that you will burn more holes through the weak spots in the tank. You can TIG braze it. I recently brazed up a tank that had been sitting for 30 years with fuel in it.

I'm sure there is something that will chemically neutralize the gasoline, I can't speak for that. I threw the tank in a vat of vinegar to remove the rust, then washed it out with simple green and hot water about 5-6 times until I was convinced it was clean. Brazed on it for close to an hour (the tank was in terrible shape) and no explosions. But just because I did it doesn't mean you should, lol. If you're worried about it even after cleaning the tank thoroughly then don't mess with it.

Alternatively you can bring it to a radiator shop and have them hot tank it and seal it up, if you can find a place that will do it.
« Last Edit: Nov 07, 2016, 15:42:20 by advCo »
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Offline magazine

  • Posts: 47
Re: 1980 SR250 Build, get Excited
« Reply #11 on: Nov 08, 2016, 08:57:55 »
My SR250 had similar tank problems.  I JB welded it up and painted it for the moment but have been looking at new tanks for a while now.  I have found a few, and am considering some on Ebay out of China.  Here is one in particular that I think could work.  This one in particular does not have dimensions listed. 
http://www.ebay.com/itm/Motorcycle-Vintage-Fuel-Gas-Tank-Honda-CB100-K3-Cafe-Racer-New-Plain-No-Color-/272221018355?hash=item3f61a318f3:g:5fIAAOSwubRXGwzJ&vxp=mtr

Here is another that has a little more café style to it with a huge tunnel. 
http://www.ebay.com/itm/2-4-Gallon-Cafe-Racer-Gas-Fuel-Tank-Universal-Custom-Tank-for-Honda-Yamaha-BMW/232082007070?_trksid=p2047675.c100623.m-1&_trkparms=aid%3D222007%26algo%3DSIC.MBE%26ao%3D1%26asc%3D39823%26meid%3D30e1ede16f9b480ca0e36c6b19b796f2%26pid%3D100623%26rk%3D1%26rkt%3D6%26sd%3D272221018355
« Last Edit: Nov 08, 2016, 09:02:18 by magazine »

Offline monkeyinfantry

  • Posts: 13
Re: 1980 SR250 Build, get Excited
« Reply #12 on: Nov 08, 2016, 12:42:42 »
My SR250 had similar tank problems.  I JB welded it up and painted it for the moment but have been looking at new tanks for a while now.  I have found a few, and am considering some on Ebay out of China.  Here is one in particular that I think could work.  This one in particular does not have dimensions listed. 
(pic)

Here is another that has a little more café style to it with a huge tunnel. 
(pic)

Yeah I've been looking at alternative tanks too, and that second one you linked looked promising, I just haven't got around to measuring the mounting points or anything, and I'm still not sure what direction I want to go in. I bought some MDF but still not sure if I'm going to dive into making my own tank.

Offline thefish

  • Posts: 112
Re: 1980 SR250 Build, get Excited
« Reply #13 on: Nov 29, 2016, 10:31:40 »
Following!
What's the update?


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Kamn

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Re: 1980 SR250 Build, get Excited
« Reply #14 on: Nov 29, 2016, 11:33:59 »
Got a few more for ya  ;)


I've researched welding up this tank and frankly welding on an already used tank is sketchy to me and I'm not willing to risk blowing myself up, maybe I'll attempt it at a later time when I get ballsier ;D I've also looked up some brand new gas tanks and the nice ones range from $400 - $600 which is ludicrous, only cheap ones you'll find are either from China (no thanks) or are tiny peanut tanks that would not go well with the bike at all. 



You don't need to worry about blowing yourself up if you are welding or brazing a tank, just clean it and let it air for a day or two and you're good to go.......Have welded tanks before with no issue or worry, the only people that have had problems are the morons that do it with gas still lingering in the tank.
Your best and fastest option is to braze like AdvCo has stated, especially where your hole is......that formed area will have less of a chance of warping from heat. Once its brazed or welded, seal the tank from the inside with products like POR15.

Offline xb33bsa

  • Posts: 7726
Re: 1980 SR250 Build, get Excited
« Reply #15 on: Nov 29, 2016, 11:36:34 »
with correct precautions you can safely weld on a tank that still smells of gasoline
all, needs be done is for combustion of any fumes to be made a certain impossability
and an absolute fool proof,cheap, method is a few chunks of dry ice tossed insided
keep the cap on and just the petcock removed as the dry ice boils into a gas co2 is what will be talking up space and with the small outlet the you can easilly see when the flow stops and its time for another lil chunk or 2 brazing those holes is done with a very close form fitting sheet metal overlay ,sized well beyond the hole to hopefully encounter thicker metal
do not put dry ice in a sealed container  that will make a bomb with no fire ..

Offline monkeyinfantry

  • Posts: 13
Re: 1980 SR250 Build, get Excited
« Reply #16 on: Nov 29, 2016, 19:28:25 »
Almost been a month since I last posted, no I didn't blow myself up  :P I've been busy with college and went up to my cottage for the holidays. I've also been mainly focusing on my buggy project cause I'd like to get it done for next season. I'll put the build in my sig for anyone who is interested, personally I'm a member of many forums because all sorts of fabrication interests me. I know some forums are iffy about linking to other forums, but hopefully it's ok considering it isn't another motorcycle forum.

As for the bike, no more pictures yet, I drew up some more braces for where the main seat tubes meet the frame's backbone. I just need to mark them up on some metal, cut'em out, and tac. After that I'll start to re-fabricate the top shock mounts so she can stand on her own feet.

I still haven't decided what I'm going to do with my gas tank, leaning more and more towards attempting to braze it up and hopefully I dont go kaboom. Found out dry ice is harder to attain than just walking into a chain store, might look into a purge setup for my TIG. I'll probably give it the simple green and hot water treatment a few times and do a flash burn with all openings unplugged to make sure the fumes are fully out, then hopefully when I braze it I dont turn into living Swiss cheese. More to come.

Offline xb33bsa

  • Posts: 7726
Re: 1980 SR250 Build, get Excited
« Reply #17 on: Nov 29, 2016, 22:22:38 »
Almost been a month since I last posted, no I didn't blow myself up  :P I've been busy with college and went up to my cottage for the holidays. I've also been mainly focusing on my buggy project cause I'd like to get it done for next season. I'll put the build in my sig for anyone who is interested, personally I'm a member of many forums because all sorts of fabrication interests me. I know some forums are iffy about linking to other forums, but hopefully it's ok considering it isn't another motorcycle forum.

As for the bike, no more pictures yet, I drew up some more braces for where the main seat tubes meet the frame's backbone. I just need to mark them up on some metal, cut'em out, and tac. After that I'll start to re-fabricate the top shock mounts so she can stand on her own feet.

I still haven't decided what I'm going to do with my gas tank, leaning more and more towards attempting to braze it up and hopefully I dont go kaboom. Found out dry ice is harder to attain than just walking into a chain store, might look into a purge setup for my TIG. I'll probably give it the simple green and hot water treatment a few times and do a flash burn with all openings unplugged to make sure the fumes are fully out, then hopefully when I braze it I dont turn into living Swiss cheese. More to come.
flash burn there is one safe way to do that ,you got fumes coming out a hole fed by some flow behind it
put screen over the hole not chicken wire but pretty fine screen
flame cannot travel back thru screen srsly its a fact,its the similar principle to a gas lantern with silk globe, its an old tank welders trick
used to be easy to get dry ice ,safeway or the liqueer store
you can also get these little co2 deals that you put a cartridge in... it pierces and from what i understand releases it kinda slow
the guys that pull out the old gas station tanks use em ,puncturte cartrige and toss it in the tank for a mild time release effect
exhaust can be use as purge as well
« Last Edit: Nov 29, 2016, 22:26:46 by xb33bsa »

Offline Weldangrind

  • Posts: 84
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Re: 1980 SR250 Build, get Excited
« Reply #18 on: Dec 31, 2016, 21:59:27 »
I used a product that is designed for removing calcium, lime and rust (quite similar to CLR, which is commonly available in Canada).  I was only using the liquid to remove rust from the tank, but when I poured it out and rinsed the tank, there was no hint of gasoline vapours.  I then heated the side of the tank to cherry red while I pushed out some dents.  Since that went well, I also welded some sheetmetal over the pinholes near the petcock.  It's not a nice tank to begin with, so I'm not worried about how it looks.  It didn't blow up and I have all of my fingers.  YMMV.

Offline Eleganten

  • Posts: 116
Re: 1980 SR250 Build, get Excited
« Reply #19 on: Jan 10, 2017, 19:37:06 »
Sweet fabrication on that frame!


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