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750 Sport fuel lines routing

Posted: Wed Aug 22, 2018 7:37 pm
by 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... :cool:

Re: 750 Sport fuel lines routing

Posted: Fri Aug 24, 2018 11:03 am
by 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

Re: 750 Sport fuel lines routing

Posted: Sun Aug 26, 2018 3:26 pm
by 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?

Re: 750 Sport fuel lines routing

Posted: Sun Aug 26, 2018 3:34 pm
by 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.
Desmo Tutu wrote: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?

Re: 750 Sport fuel lines routing

Posted: Wed Sep 05, 2018 8:48 pm
by 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.

Re: 750 Sport fuel lines routing

Posted: Wed Sep 05, 2018 10:14 pm
by 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,

Re: 750 Sport fuel lines routing

Posted: Thu Sep 06, 2018 7:16 am
by steveT2
You have me thinking now, should i or shouldn't i .

Re: 750 Sport fuel lines routing

Posted: Thu Sep 06, 2018 9:01 am
by paso750
usually the jet was screwed into the Y piece. When the fuel hose is pulled off it would sometimes remain in the hose.

Re: 750 Sport fuel lines routing

Posted: Fri Sep 07, 2018 6:33 pm
by steveT2
Oh well..... I managed to squeeze some 5mm hose into the 8mm return hose, will see how it goes.

Re: 750 Sport fuel lines routing

Posted: Mon Oct 22, 2018 6:52 am
by 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... :cool:

Re: 750 Sport fuel lines routing

Posted: Fri Oct 26, 2018 9:13 pm
by Antomonster
Desmo Tutu wrote:What is the routing for the fuel tank breather pipe?
- https://www.stein-dinse.biz/eliste/?sid ... 28cb&lg=de :shock: