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Author Topic: Soft gas tank top  (Read 971 times)

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Offline Krankyoptimist

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Soft gas tank top
« on: January 02, 2015, 08:26:22 PM »
I have a tank for my 76 550 that is very soft on the left side top and firm as can be on the right side top.  Meaning that I can easily push down a dent in the left side.  It will pop right back to shape but I can't imagine ever being able to lean on the top of this tank with a forearm or anything.  Over all the tank is in great shape with original paint and no dents.  I had to do some electrolysis on it to get rust out of it but now the inside looks great with just some pitting on the hump right under the cap.  Questions:
1.  Any opinions on why this thing would be soft on one side and not the other?  Is this common with these Honda tanks?
2.  Safety of using the tank?
3.  If I line it with caswell's will it help rigidity at all or will I risk the caswell's popping loose inside the tank?  I've never used Caswell's.

It would be a shame to ditch a tank with such a great exterior.
Thanks for any commentary.
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Offline goldarrow

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Re: Soft gas tank top
« Reply #1 on: January 02, 2015, 09:00:56 PM »
Something is wrong with your tank
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Offline DWS

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Re: Soft gas tank top
« Reply #2 on: January 03, 2015, 12:08:23 AM »
Use a mirror to see if it is rusting out
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Offline dave500

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Re: Soft gas tank top
« Reply #3 on: January 03, 2015, 01:41:47 AM »
maybe it has a large dent underneath and the bondo is lifting?as already suggested try and poke a mirror in and look,you can also try a magnet over the tank to feel for thick bondo.
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Offline Don R

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Re: Soft gas tank top
« Reply #4 on: January 04, 2015, 10:58:58 AM »
bondo doesn't flex much, it would pop loose or crack if it flexed much. I'd look for a better one.
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Offline arogers88

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Re: Soft gas tank top
« Reply #5 on: January 04, 2015, 05:45:29 PM »
Doesn't sound like rust, or filler. Sounds like someone popped out a dent with some heat/cold...
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Offline Krankyoptimist

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Re: Soft gas tank top
« Reply #6 on: January 04, 2015, 08:31:44 PM »
Thanks for the replies.  When I first dumped the tank I was a bit taken aback by how much rust flake came out of it. Quite a pile.  Apparently it all must have come from the left side of the tank.  I could look for another tank but would probably get something with as many or more issues I suspect.  Besides it took two weeks worth of electrolysis to clean this one out!  That was a PITA.

Wonder if I could slightly dent in that side and braze more thickness there or maybe lead it.  No experience with that but...The tank is as clean as a whistle have been degassed/degreased/acetoned/washed about ten times.  Maybe it wouldn't blow my head off.  ???
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Offline 754

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Re: Soft gas tank top
« Reply #7 on: January 04, 2015, 11:30:02 PM »
Get in with a borescope and have a look, hopefully its on the petcock side....my scope could probably get in up thru. The petcock bung, but some are too big to fit.

Tanks are made of three main pieces,  seam down the middle of the top. If you can see the bad area, might be able to cut and splice.. But I imagine that you went to all the work so far cuz the outside was. Nice.
 
 Sounds like it got water in it and then laid on its side or upside down.
« Last Edit: January 04, 2015, 11:34:30 PM by 754 »
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Offline goldarrow

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Re: Soft gas tank top
« Reply #8 on: January 05, 2015, 06:11:40 PM »
Send the tank over to calj737, he's professional with metal work and paint, he may even do it to you for free 8)
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Offline goldarrow

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Re: Soft gas tank top
« Reply #9 on: January 05, 2015, 07:43:10 PM »

Quote from: calj737 on January 05, 2015, 07:37:29 PM
Quote from: goldarrow on January 05, 2015, 06:11:40 PM
Send the tank over to calj737, he's professional with metal work and paint, he may even do it to you for free 8)
You're right, for him I might. You get the Mothered-in-law rate.

Thanks, but no thanks.  I use only stock oem tank with stock paint.  Far more superior than your professional paint job
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Life Is Full Of Challenges - And My Backyard Is Full Of SOHC4's

CB550 K0
CB750 K0, K2, K23 JDM, K45, K5
And the little ones z50r, xr50r, st90


750k5 http://forums.sohc4.net/index.php?topic=114817.0

Offline Krankyoptimist

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Re: Soft gas tank top
« Reply #10 on: January 05, 2015, 09:20:01 PM »
That side of the tank actually doesn't pop in and out like "boing bing", it is just flat mushy. Like it's make out of aluminum flashing or something. I can't possibly imagine it holding paint. But it has so far. I think it's a cut patch job for sure. Rut ro another learning curve.  :o
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