3/16 versus 1/4 Tygon Fuel Line...

[AAAltered]

When plumbing an R5, does 1/4" Tygon stay fitted without clamps?

I realized I had 3/16 on there, and a supply of 3/16 in the shop.  Meanwhile, i got a supply of 1/4 as well as the 1/4"  Motion Pro disconnect. 

I don't want to run fuel line clamps, and never had to with the 3/16.  Whats the experience with using 1/4?

1/4 next to 3/16:



1/4 on the tank crossover:



1/4 Motion Pro cross over:



3/16 on the left, 1/4 on the right:

[Czakky]

I always used 3/16 w/ no clamps... fwiw.

[27 Cycles]

Same here, usually 1/4" hose will leak.  1/4" barbs and 3/16" fuel rated rubber hose won't leak with no clamps.

[m in sc]

yup 3/16. and at least use a small wire tie if in doubt.

the crossover -does- seem to take a 1/4" 'ok'.

still, use a tie, a spring slip, something.

[sav0r]

3/16 for all the lines, the quick disconnect on the crossover doesn't like the 1/4, but the tank bungs seem okay with it... But I always tie my lines, the bike wont pass PA inspection without it, not that I've ever gotten a bike inspected...

[EE]

Unless..  You have big carbs on a hot engine then the extra volume in the fuel lines helps make sure you don't run your floatbowls dry on a long WOT straight..

[1976RD400C]

When in doubt

[Djg8493]

3/16 for all the lines, the quick disconnect on the crossover doesn't like the 1/4, but the tank bungs seem okay with it... But I always tie my lines, the bike wont pass PA inspection without it, not that I've ever gotten a bike inspected...

Is that really a requirement in PA, haha, I never knew that and I worked in a shop in PA and inspected bikes for 6 or 7 years.  Unless it was leaking or had residue we didn't fail much for fuel issues.  We weren't the strictest shop by the book, mostly focused on safety issues so I'm sure you are right, it's just one I hadn't heard of before. 
My experience with 1/4 Tygon lines (especially if they are "Tygon" from eBay/Amazon) they will leak at the petcock when the temp gets warm if they are not tied on.  I've had good luck with quality Zip Ties pulled tight with pliers.

[pdxjim]

I usually get the 3/16" as I hate fiddling with clamps.

That said, I just picked up more clamps (both kinds) than I will use in a lifetime for next to nothing.

https://www.amazon.com/gp/product/B07J3Z5LYY/ref=ppx_yo_dt_b_asin_title_o08_s00?ie=UTF8&psc=1

https://www.amazon.com/gp/product/B072Q78QMB/ref=ppx_yo_dt_b_asin_title_o09_s00?ie=UTF8&psc=1

[oxford]

Unless..  You have big carbs on a hot engine then the extra volume in the fuel lines helps make sure you don't run your floatbowls dry on a long WOT straight..

How big of carbs and how much motor work before the 3/16" lines become a problem?

[EE]

Thats hard to say I've run into it several times over the years. You'll usually outflow the stock petcock first, but then larger fuel lines allow you to get away with it a little longer because it acts like a reserve, i had an RZ roadracer friend, he built his bike i built mine and we went out racing together, he was having fuel starvation problems but he didn't have the time or money before the race the next day for a bigger fuel valve but he was a welder so i told him run home and built a fuel log, the fuel valve feeds into the fuel log that acts like a reservoir, sure he really needed a bigger fuel valve but it worked great and i don't think he ever changed it out.

[whymee]

If you want some clamping force, But do not want to use a conventional clamp. Cheap and easy...

[m in sc]

that heatshrink?

[whymee]

that heatshrink?

No Mark,

That is a small piece of the main line, stretched over the OD of the same line.

Easy Peasy!

[m in sc]

oh i gotcha. interesting. very clean looking.