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Old 12-07-2014, 09:53 PM
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Davezilla Davezilla is offline
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Location: San Antonio Texas
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Default Re: Motorized Bicycle Take a Tip...Leave a Tip

Originally Posted by MEASURE TWICE View Post

Thanks for the tip!

I am thinking of using this so that a bend should have less crimp at a bend, that could take away from the inner diameter that would make more restrictive flow of the gravity feed in a fuel line.

I think I'll have to try this. Only I have had problems with some clear tubing from the hardware store made specially for gasoline, and it not sealing well on the connection. I have however found the black rubber lines compress and seal well with the worm gear drive strap hose clamps really good. I bet clear tubing is only going to take the bend and keep it as it has something to do with the kind of material the tubing is made of.

Any idea for a specific type of clear tubing that will hold the shape form and also seal well?

There are different types of these clear plastic fuel line tubings, the cheapest being the vinyl tubine like aquarium tubing, it can be used for fuel temporarily because it will harden fairly quickly after gasoline is introduced to it, then there's the polyethlyne type that can resist gasoline a little better but still hardens up and becomes brittle, which also leads to leaking, this stuff is much better than the vinyl type but still not the best. The Tygon fuel lines tho can resist gasoline and alcohol best and won't become brittle over time.

The other issue is the clamping... These lines do best with the spring type pinch clamps or fuel injection hose clamps, the worm screw type radiator hose type clamps don't work so well for any tubing under about 3/8" or 10mm simply because they won't stay round once tightened up past a certain point.
The fuel injection hose type clamps are the most secure type and will stay round, but the springy pinch clamps will usually suffice when there's no pressure to deal with.

Another thing to look out for is that some of these lines come in standard and metric sizes. 6mm looks a lot like 1/4" but it's slightly smaller, a 1/4" hose will slip over a 6mm barb but won't be as tight as if it was over a 1/4" barb, same as a 7mm hose over a 1/4" barb, it'll fit but it'll be loose enough for the fuel to either leak or harden up a cheaper type of plastic line. This can be avoided by measuring the hose barbs then ordering the correct size line. About the only standard size that's compatible with metric would be the 8mm or 5/16" they're the closest match. This mis match in size between standard and metric becomes more of a problem under 1/4" or 7mm and less of a problem above 1/2" but can still be a problem if plastic lines are being used.

Not really going against what you're saying, but just a little more info since these lines look quite the same but can be very different in size and how well they handle fuel. my tygon lines have lasted 4 years so far without becoming hard or leaking, but the cheaper line I used on the Sportster started to leak about 6 months after installation.
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