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NT Speed Carb - Leaking Banjo-Bolt Connection

The ins and outs - carburetors, manifolds, mufflers, expansion chambers and more to keep your motorized bicycle running the way you like


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Old 02-02-2013, 11:16 AM
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Angry NT Speed Carb - Leaking Banjo-Bolt Connection

OK, this has been driving me nuts for the past week, and my fuel-efficiency has been cut in half because of it. My carb started leaking @ the banjo connection, one drop about every 4-seconds. This leak is NOT the valve; I have definitively reduced it to the washers. I have tried crushable copper, rubber, nylon, some other plastic, and in desperation I even tried hot-glue. I can't get the durn thing to stop dripping. It's been frustrating enough that I'm considering getting another NT Speed, or maybe grab my nuts and go for a DAX RT. I love this carb to death, but this problem is really getting my goat. I thought maybe trying some JB Weld, but that really seems half-assed. I'm baffled. Suggestions?
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Old 02-02-2013, 11:23 AM
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Default Re: NT Speed Carb - Leaking Banjo-Bolt Connection

Make sure that there are no raised surfaces or burrs, factory buggers, ect that can prevent the sealing washers from making a full 360 degree seal. Also try sealing it with Hylomar, a thin coating on both sides of the sealing washers.
Hylomar is available at most auto parts stores. Even the copycat Permatex branded Hylomar works good, just make sure you get one labeled Hylomar if buying the Permatex brand as Permatex makes all sorts of sealants.

A little tip, Acetone is the only good solvent I have found for cleaning the stuff of your fingers. Paint thinner, gasoline, lacquer thinner all have little if no affect on it.
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Last edited by GearNut; 02-02-2013 at 11:25 AM.
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Old 02-02-2013, 12:41 PM
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Default Re: NT Speed Carb - Leaking Banjo-Bolt Connection

Thanks GearNut! I'll give that a try. I actually made a half-assed attempt at flattening the surfaces with the Dremel in my quest; I'll make another concerted effort (using Hylomar) and report back.
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Old 02-02-2013, 09:11 PM
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Default Re: NT Speed Carb - Leaking Banjo-Bolt Connection

There is another product called SealAl. It's made to repair gasoline leaks in fuel tanks, fitting, etc. I've never read the ingredients so it might contain Hylomar. Whatever it is it seems to work.

It does have a short shelf life after the tube is opened. A few weeks and it starts to harden in the tube even if the cap is screwed on tight. It's available at most auto parts stores.

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Old 02-03-2013, 08:02 AM
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Default Re: NT Speed Carb - Leaking Banjo-Bolt Connection

If you want to flatten the surfaces you gotta use a piece of very fine emery board (fingernail file) or fine, like 1000 grit sandpaper and a homemade sanding block.
The issue here is the surfaces need to be flat and must be a true 90* to the bore of the banjo bolt. Any off angle sanded into the carb body or banjo fitting can spell disaster.
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Old 02-03-2013, 11:42 AM
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Default Re: NT Speed Carb - Leaking Banjo-Bolt Connection

Using copper washers works for me on the Banjo's.
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Old 02-06-2013, 12:21 PM
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Default Re: NT Speed Carb - Leaking Banjo-Bolt Connection

Hey guys,

Just an update: I tried flattening out the mating surfaces and used copper-washers with Permatex 1B without success. I finally ended up wrapping the washers with a few layers of teflon-tape and it's working well...no drips at all. I'll probably bag the banjo altogether and replace it with a 90-degree connection. Man, what a hassle.

Thanks again for your input.
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