750 Sport fuel lines routing

[Desmo Tutu]

Need some help with my 750 Sport I picked up in bits & boxes. The bike is soon to be completed, but I have a question about the fuel lines. The bike has the stock Weber.
Inside the tank there is a bit of fuel hose directly from the pump to the pipe going from the top too the fuel tap. So no internal filter. It seems a previous owner has mounted the fuel filter outside the tank, because there was a filter in one of the boxes. But how is the fuel line suppose to run?

My first thought is from the tap on the right side, in front of the rear shock, then around the left side of the rear cylinder, cross between the cylinders, through the Y-pipe to the Weber. Or does it run from tap, front of rear shock, then over the cylinder head either over or under the frame brace and down to the Y ?
I guess I can put a new filter somewhere between the tap and the Y.

Oh, and I need a seat cover if someone have a spare or know where to get one...

[MatthiB]

Hi Tutu,

I ran both lines, the one from the tap to Y and the return line from Y to the socket at the bottom of the tank over the cylinder head under the frame.
For a cleaner look that is.

Btw. make sure you have a smaller diameter hose for the return line.
It does not necesseraly have to be a (120) jet.
My Weber runs pretty good with a piece of 5mm hose inside the 8mm fuel line.

Cheers

[Desmo Tutu]

Thanks, I will try that route. When you say make sure not to run 8mm on return, is that if you don't have the restriction jet, or even if you have the jet?
I was going to replace all fuel lines with fresh 8mm fuel line. But you advice me to go 5-6mm on return line? Does this matter as long as i have the jet in the return line?

[MatthiB]

It's either or.
If you have a jet in the return line it's fine.
You're good to go with 8mm hoses for all three bits.

Thanks, I will try that route. When you say make sure not to run 8mm on return, is that if you don't have the restriction jet, or even if you have the jet?
I was going to replace all fuel lines with fresh 8mm fuel line. But you advice me to go 5-6mm on return line? Does this matter as long as i have the jet in the return line?

[steveT2]

Neither of my bikes as a jet or smaller hose on the return, both bikes run fine (750 sport and the 900 both with the Webber) is this a mod or standard.

[MatthiB]

Standard is a 120 jet in the return line.
But in my opininion that's too small.
Depending on the fuel pump pressure that could give too much pressure to the needle valve with the risk of overflooding the carb.

If your pressure system feeds the carb just enough to keep the fuel level OK at full gas with no restriktion in the return line - perfect,

[steveT2]

You have me thinking now, should i or shouldn't i .

[paso750]

usually the jet was screwed into the Y piece. When the fuel hose is pulled off it would sometimes remain in the hose.

[steveT2]

Oh well..... I managed to squeeze some 5mm hose into the 8mm return hose, will see how it goes.

[Desmo Tutu]

What is the routing for the fuel tank breather pipe?
I have the european version, in case there is a US anti-smog version with some crazy piping...

[Antomonster]

What is the routing for the fuel tank breather pipe?

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