CB750 Gas Line 🤔

[compadre]

Hello everyone, just thought I would come by in hopes to implore the wisdom of some CB wizards.
I am replacing the fuel lines on my CB750 and I’m lost..
the first issue is my fuel line immediately hits my frame after the tank so I need a 45Degree bend. The second issue is I have no idea what to buy to make everything work. They don’t seem to make stainless in 5.5mm. I considered using actual copper line which would be cool but I’m still unsure what to purchase.
Does it matter what size line I use? And if I want stainless or brass what are your suggestions?
Thanks!

[TriNortchopz]

5.5mm = 0.217" why so small? I would not go under a 1/4" for fuel lines...do you have just the one outlet from the tank? that 4-cylinder gonna be thirsty and needs to be fed. 5/16" would even be better.

surprising to me that stock Honda had such small diameter tubing, "Many people ask me when I build my carburetors on the CB500, CB550, CB650 and of course the CB750, what fuel line do I use, Many have tried cheaper hose and they really cannot touch the Genuine hose that Honda have always used. it will fit hundreds of Honda’s as a lot are 5.5 ID. and a 10.5 Outer Diameter."

https://carpyscaferacers.com/shop/shop-our-store/motorcycle-parts-accessories/honda-cb500-cb550-cb750-parts-upgrades/honda-hose-there/

For frame clearance, not sure what the issue is from the photo, as I don't see the frame in the photo.
Can you just use a petcock with a 90 degree outlet line to fit into the tank? what is the thread of the tank outlet?

If you want hard lines,an option could be to go with cupro-nickel - easier to bend than stainless and more durable than copper;

"Cupronickel tube has become the go-to material for both shops and Do-it-yourself customers when replacing brake and fuel lines. This tubing will not rust over time like regular steel tube and is far easier to bend and flare. Kits are available with or without brake line fittings and gravel guard spring."

https://www.thestopshop.com/collections/copper-nickel-cupronickel-tubing-kits

[docmel]

Yes, size matters. I'm not into braided stainless lines, too expensive and somewhat what user unfriendly with no performance benefits. Hard to route in tighter aeras and will rub pain, chrome or wire insulation right off anything it touches

Get rid of that plastic line. Its old, yellowed and brittle and is just asking to crack and fail. Ill bet you'll have to cut the ends of the line off the fittings with a razor knife, easy day, but it will show how they shrink and loose any elasticity. Stay away from those clear fuel lines. Take a look around: No one really uses them, they dont last long, especially around heat sources. And as you can see, they shrink with age

Go to your local auto parts store and get the proper ID line (Black vynil). DONT GET the black fuel injection line. Looks the same, lots more expensive, not needed. Black lines are cheap, last, easy to route

Brass or copper lines are a PIA to fit and you will need flaring tools, bending tools and the proper flare fittings on your bike to begin with to use them

If I see the pic correctly, a black line will fit between those two fittings with a little finagling and a little slack and shoud eliminate that slight bend.

HINT: Loosen upor reomve the gas tank mounts so you can slide it a little back and forth to give you a little working room. Oil up those male fittings before sliding on the new lines for a easier install.

It may take you a few tries till you get the exact length you need once the tank is tightened back up, so dont cut the line too short to begin with. Start a little long and try numerous fits and trims until you get the exact length you need.

By looking at the pic, a good fit once done might look like a slight curve in the shape of a slight "S" but thats ok

Use good quality fuel line clamps, dont go cheap, and dont over tighten

I cant remember, but I beleive you need 3/8" lines

They also make all sorts of fittings that go from anywhere from straight to 90 degrees that you can plumb into lines as needed, but in this case I dont beleive you will need them

[docmel]

So whats up? Share what you did to fix it so others can learn from your experience

[EVILBLACKSABRE]

I needed a section of fuel line with a 90 degree bend, and I thought to myself how great it would be if someone sold sections of fuel line molded at different angles. I went online looking for such a thing, and to my surprise, they do. A length of fuel line with a variety of different angled molded bends in it. They're not cheap ($19+ shipping) but it was exactly what I needed so I was happy to pay.

I don't know if this will help you, but I thought I'd post it. They sell them in different size ID's-

https://www.amazon.com/Universal-Molded-Fuel-Line-Rubber/dp/B07C8YTNPF

Also, it's hard for me to tell from the picture, but couldn't you simply cut off a section of the part of the frame that's causing the obstruction?

[farmall]

I don't know if this will help you, but I thought I'd post it. They sell them in different size ID's-

https://www.amazon.com/Universal-Mol.../dp/B07C8YTNPF

Nice find which beats rummaging at auto stores!