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Discussion Starter · #1 ·
GDay,
Trying to sort the fuel system out on my 1990 900ss , I have a manual and parts listing but am still struggling with the fuel line route, it seems to squeeze in between the frame and the head ? Looks pretty tight up there? And also does anyone know the size of the jet that is in the fuel line that returns to tank ? I don’t have one and was going to drill out a bit of brass to suit. Just need the size.

thanks guys
 

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I have no idea of the size but the concept is not to let ALL the fuel return to the tank so if you make a pill that is snug in the line and drill an orifice restrictng return of fuel to about half the diameter you should be fine.
There is a thread about line routing on the 90’s SS active right now. I personally re- routed my fuel lines to stay away from the engine, meaning outside the frame, away from engine heat . In order to do that, plus add an inline fuel valve, I made the lines much longer.
Use reinforced fuel line that won’t kink or collapse when warm . Clear plastic line will melt in seconds , and can collapse causing fuel starvation.
 
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The original "pill" in the line is brass. You would want to use something that won't react with the fuel. I have wondered if the return line could be partially collapsed with a zip tie and perform the same function as the "pill".
 

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Discussion Starter · #7 · (Edited)
So I ground down an old brass fitting I had and it now reduces the 8mm hole to 5mm.
I also decided to run the fuel around the vertical head as I have much more comfort with it there. I may have to run a T instead of a Y as I can’t seem to find one I have costed the area wher I will put the T. I will put a pressure gauge at the inlet to the carb and check to see how the return line and the 4.5 mm jet works.
 

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Discussion Starter · #10 · (Edited)
So I think I need to put a smaller pill in it. Ran out of fuel after a few minutes, and when I blocked the return line completely it flooded , so I guess somewhere between it should work. I put a 120 size jet in. Still idles for a couple of minutes then stops 🤷🏻‍♂️
 
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