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Author Topic: Fuel tank outlet thread size?  (Read 3205 times)

Ricks

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Fuel tank outlet thread size?
« on: April 29, 2012, 11:00:08 AM »
What is the thread size of the fuel tank outlet.  I thought it was 1/8" npt, but it's not.

Rick
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Ricks

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Re: Fuel tank outlet thread size?
« Reply #1 on: April 29, 2012, 12:00:57 PM »
On further investigation, I have found that my automatic tanks do indeed have 1/8 npt, but my earlier style does not.  It appears to be a 7/16-20 straight thread, as a 1/4" compression fitting I had lying around screws right on.  Which fuel sediment bowl do I need for this?

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Ricks

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Re: Fuel tank outlet thread size?
« Reply #2 on: September 07, 2013, 01:42:17 PM »
Since this topic came back up, I will answer it here.

As I said, a 1/4" compression fitting screwed right on.  I went to the local NAPA, and in their cabinet of fittings, they had an adapter that went from the compression fitting to the NPT thread.  I don't have that bike anymore to take a picture, but I think it was called an inverted flare adapter?

OK, just hit google and I THINK this is what I used: 

http://www.amazon.com/Allstar-ALL50121-Straight-Inverted-Adapter/dp/B006K8MH2U/ref=pd_sim_auto_4/178-5327437-5078200


BTW, they do not make a fuel filter that screws on to the 1/4" compression fitting, as far as I or Wayne could find.
« Last Edit: September 07, 2013, 01:49:55 PM by RickS »
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SIMPLEXUSA

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Re: Fuel tank outlet thread size?
« Reply #3 on: September 07, 2013, 02:36:29 PM »
mine is a 24 tpi thread per inch.  it  looks to be 7/16 regular thread.  I  have a1958  wheel horse tractor.  it takes a smaller thread. I just assumed my cycle tank was the same.
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Ricks

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Re: Fuel tank outlet thread size?
« Reply #4 on: September 07, 2013, 03:10:14 PM »
Quote from: SIMPLEXUSA on September 07, 2013, 02:36:29 PM
mine is a 24 tpi thread per inch.  it  looks to be 7/16 regular thread.  I  have a1958  wheel horse tractor.  it takes a smaller thread. I just assumed my cycle tank was the same.

I just measured a  1/4" compression fitting at 24 tpi.  The outside diameter is approximately 7/16".  I would bet it is the same as the one I had.
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Re: Fuel tank outlet thread size?
« Reply #5 on: September 07, 2013, 09:44:22 PM »
Rick, I ended up running a die over the outlet. 1/8 pipe thread.  it worked like a champ.  thanks for all your help.
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Ricks

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Re: Fuel tank outlet thread size?
« Reply #6 on: September 08, 2013, 05:21:14 AM »
Glad you got it worked out.

1/8" NPT only has 18 tpi.  The diameter is slightly less than a 1/4" compression fitting.  Funny thing is, a 1/4" compression fitting will "sorta" screw on to the 1/8" npt and stay there.  I don't think it would have any chance of holding fluid without massive amounts of teflon tape or paste.
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