S4 fuel tank spigots ??

jerry · 03-12-2023, 10:02 AM

Fitting new fuel lines to S4

4 spigots 2 are breather /overflows 5mm they are obvious

then there are 2 x 8mm spigots one is main flow from pump in tank the other is return line from Fuel injectors..... I think that the rear one is from pump ??or its bottom one when tank is vertical ,,

unfortunately the orange sticker that explains all has been painted over by the sprayer !!!! dirrr even though I remeber masking it off 3 years ago when I started the refurb .

its now 90% finished just waiting for fuel tank flange , new battery , oil and fuel to try and start it up ??????

Dukedesmo · 03-12-2023, 11:24 AM

Depending on where the pressure regulator is, it may not matter which is flow & return? e.g. on a 916 the regulator is in the tank and so the fuel can flow either way through the injector bodies as it is simply a 'loop' - that said space constraints means they only really fits one way round, the original hoses should have an M (Flow) and R (Return) on them somewhere.

Otherwise power it up from a battery with a small amount of fuel in it - will be obvious which is the flow!

slob · 03-12-2023, 11:35 AM

depends a bit on whether you put the parts back in the tank the right way round.
return should be the one that leaks uncontrollably when you disconnect the hoses ;-)

jerry · 03-12-2023, 05:34 PM

Quote:

Originally Posted by slob

depends a bit on whether you put the parts back in the tank the right way round.
return should be the one that leaks uncontrollably when you disconnect the hoses ;-)

Yeah that diagram show it as it is , so im OK rear lower spigot is feed

03-12-2023, 10:02 AM	#1
jerry Old Git Join Date: May 2006 Location: Cricklade Bike: Multiple Monsters Posts: 2,897	S4 fuel tank spigots ?? Fitting new fuel lines to S4 4 spigots 2 are breather /overflows 5mm they are obvious then there are 2 x 8mm spigots one is main flow from pump in tank the other is return line from Fuel injectors..... I think that the rear one is from pump ??or its bottom one when tank is vertical ,, unfortunately the orange sticker that explains all has been painted over by the sprayer !!!! dirrr even though I remeber masking it off 3 years ago when I started the refurb . its now 90% finished just waiting for fuel tank flange , new battery , oil and fuel to try and start it up ?????? __________________ MONSTERMAN

03-12-2023, 11:24 AM	#2
Dukedesmo Registered User Join Date: Sep 2010 Location: Leics Bike: M900 Posts: 2,894	Depending on where the pressure regulator is, it may not matter which is flow & return? e.g. on a 916 the regulator is in the tank and so the fuel can flow either way through the injector bodies as it is simply a 'loop' - that said space constraints means they only really fits one way round, the original hoses should have an M (Flow) and R (Return) on them somewhere. Otherwise power it up from a battery with a small amount of fuel in it - will be obvious which is the flow! __________________ M900, 916, LeMans II.

03-12-2023, 11:35 AM	#3
slob . Join Date: Jul 2003 Location: East London Bike: Multiple Monsters Posts: 9,733	depends a bit on whether you put the parts back in the tank the right way round. return should be the one that leaks uncontrollably when you disconnect the hoses ;-) Last edited by slob; 03-12-2023 at 11:38 AM..