Are GS fuel hoses 5/16" or 1/4"?

SixSpeedSquirrel · July 28, 2008, 05:31:09 AM

I am trying to figure out what diameter my fuel hoses are supposed to be on my bike. I searched and found some references to 1/4" fuel hoses, but the ones on my bike look like they are 5/16". Anyways, I replaced one cracked hose (with new 5/16") and rode my bike for a few days with no problems. Then I took my carbs out and played with the fuel mixture screws. Then I put everything back together and replaced another fuel line (it was cracked too) with the same style of 5/16" hose. Then I came home after the bike was parked for a few hours, and now there is a huge puddle under my bike!

Should I be using 1/4" hose instead? I got some of the clear stuff that a local motorcycle shop had, I figured it would be better for being able to see the fuel flow for future maintenance. But if the opaque grey hose that they had is better quality, I would rather have that.

Also, would it be bad to put just a little white lithium grease on a fuel nipple before I try to put a hose on it? I expect a 1/4" hose will be difficult to get on, although very snug once it is on.

GI_JO_NATHAN · July 28, 2008, 05:44:38 AM

I'm wondering this as well.

DoD#i · July 28, 2008, 06:51:43 AM

Neither, the fittings are 7mm. You won't likely find that in the US. Both 1/4 and 5/16 work, being respectively a bit smaller and a bit larger than 7mm. Some folks think they have flow improvement with 5/16 - not sure how real that is in practice. Fat automotive fuel line for pressure applications does not fit on the petcocks very well, as the connections are fairly close together.

1/4 inch = 6.35mm

5/16 inch = 7.94mm

Cyle ReCycle has polyurethane fuel line in any size you like for 80 cents a foot. Your local dealer may also. Some folks use non-fuel-rated vinyl from the hardware store - not my idea of a good time - prone to turning brittle, it's cheap enough to do it right.
http://www.crc2onlinecatalog.com/fuel_lines.htm

I suggest getting 2 feet of 1/8 inch if you are buying line - this allows you to connect to the carb drains and run into a gas can on the floor, and/or do the float height check.
http://www.bbburma.net/FloatHeight.htm

SixSpeedSquirrel · July 28, 2008, 07:26:13 AM

Yeah I can't imagine that 5/16" provides any advantage in performance & flow... the fuel lines do not seem to be something that limits performance on most motorcycles. It's not like fuel is crashing through the line at any highrate of speed.

In the interest of reliability and safety, I am going to go buy some 1/4" hoses and put them on tonight.

Thanks for the detailed reply.... that was the answer I was looking for! I will make sure I get some 1/8" line for carb draining and float height checking also.

GI_JO_NATHAN · July 28, 2008, 02:04:13 PM

Thanks!
Good stuff to know.

ben2go · July 28, 2008, 02:14:33 PM

I use 1/4 inch.It's tight but seals well and doesn't require clamps.

ATLRIDER · July 28, 2008, 02:42:37 PM

I'm using 5/16 with the clamps.

Ronin · July 28, 2008, 03:24:53 PM

Quote from: ATLRIDER on July 28, 2008, 02:42:37 PM
I'm using 5/16 with the clamps.

Ditto that..I bought mine at Lowes clear poly.Love that I can see whats going into my carbs!!

lopee · July 28, 2008, 03:37:52 PM

Im using 1/4" i.d. with no clamps. It goes on just fine with out any grease, you dont want that stuff near your fuel line or in your fuel.
Bought mine at the local suzuki dealer for $1.30 or so a foot, 5 feet is plenty, just cut to match the old lengths, replace as soon as removed from frame petcock, to keep it all straight.

SixSpeedSquirrel · July 28, 2008, 08:27:22 PM

I ended up using 1/4" on the Prime hose, and it was really hard to get on. The problem is that the line buckles when you put too much force on it to get it on... It's on decently for now, but I can't get it all the way up the hard line on the petcock (no dirty jokes...). So I went ahead and put 5/16" on the other two lines, with stronger hose clamps on them.

I will keep an eye on it for now, but it looks to be strong and secure.

I can tell just from closer inspection that my leak was probably a combination of worn out OEM clamps and tubing that is just a hair too big.

What are the options for "doing it right"? Would that involve ordering 7mm hoses, or just buying the OEM replacement from Suzuki?

trumpetguy · July 28, 2008, 10:25:08 PM

1/4" ID Tygon hose. Translucent enough to see fuel in it, and rated for fuel. A little expensive at $1/ft and it only lasts a couple of years, but no clamps needed.

ben2go · July 28, 2008, 10:43:51 PM

This is what I use.1/4 vinyl.Cheap and works well.

Tang · July 29, 2008, 07:54:55 PM

props on ben2go on this one i bought that at lowes and so far i can't complain!

lopee · July 29, 2008, 08:20:12 PM

Remember to always put the shortest spigot on first I.E. tank petcock.... put the line on the short spout first , hopefully no binding or bunching. Then put the line on the longer spout to and they both then press against each other to add the pressure for keeping them in place. You can also use a little fuel as lube and twist the lnes like screw threads to move the line somewhat easier?

ben2go · July 29, 2008, 08:22:19 PM

Quote from: Tang on July 29, 2008, 07:54:55 PM
props on ben2go on this one i bought that at lowes and so far i can't complain!

Thanks.

mach1 · July 30, 2008, 05:58:49 AM

hey ben the newer bikes cant use a 1/4 inch hose I got the same as you even heated it up and no go, I even split the sides a bit and still no go. I got a clear 5/16 and it goes on tight and stays with no clamps.

ben2go · July 30, 2008, 10:30:56 AM

Quote from: mach1 on July 30, 2008, 05:58:49 AM
hey ben the newer bikes cant use a 1/4 inch hose I got the same as you even heated it up and no go, I even split the sides a bit and still no go. I got a clear 5/16 and it goes on tight and stays with no clamps.

Great info.I'll make a note of it.Thanks for sharing.

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Are GS fuel hoses 5/16" or 1/4"?