fuel??

[bigbike-r]

ok so thanx to all those who sorted my cams out but...... another problem

the gsx600f tank works by a pipe to draw fuel and another one to do what it does.... one to draw it out and one to carry it ..... well you know cos youve got them!

well my question is by connecting the carbs up to the gsxr tank... wich takes 1 pipe and works on the principle of gravity drawing the fuel down the line ... then do i simply discard the other pipe??? or does this somehow need to be plumbed into the tank as well.......

im hoping this is the last problem i need to overcome on the build before she finally fires up again ::

[steves]

Uh...
You mean... that the petcock has two spots for fuel to come out, and your carbs only have one fuel line?

I'd probably try to see if you can swap the petcock to a newer model one that takes one line.

[bigbike-r]

no no..... my petcok has 1 line but the gsxf has 2 so the carbs on a gsx600f (pre98) have 2 lines from the carbs but my tank has only 1 place to put 1 of the pipes...... the early gsxf had 2 lines cos the fuel didnt flow till the engine was running or sommat the fuel wont flow till its starting up anyway i have 2 lines from the carb and only 1 place to put them on the tank?????

[steves]

Ah. What about using a T fitting?
Short piece of fuel line, T, Lines to each side of the carbs.

[bigbike-r]

but will that work as the other line blows out air i think.... see on the kat the fuel doesnt travel from the tank till this pipe does something to allow it to flow i thought by ignoring this pipe and just hookin up the other i would get fuel to my carbs, but it looks like its not reaching the cylinders cos it aint firing and the plugs seem too dry?

[Black_peter]

Kat 750 carbs have two lines;
one to feed carbs 1&2 and another to feed 3&4.
While I'm not 100% sure I'm guessing that the tube connects carbs 1 through 4 and the extra line (the 600 doesn't have it) is to solve some flow problem.
I have wanted to do some custom work to the tank that involves running one tube from the tank. So I'm interested in how this works out for you.
The gas is still fed by gravity. A "T" in the lines somewhere should solve your issue. Unless, like I was wondering it is a flow issue. I was going to put some effort into calculating the maximum fuel flow rate then the maximum flow rate of the tubing, but hey I haven't gotten to it yet!

I had one line pop off while riding. The engine felt like it was only running on 2 cylinders. I thought I lost a coil. Turned out it was the line and the gas I was smelling was not the unburned fuel from the pipe but the unburned fuel on my shoes! I can't say that the carbs were starved because no fuel was flowing to the 1-2 tube because gas was also pouring out of the tank!

[bigbike-r]

hmmmmm thats interestin..... the line in question when you turn the engine over blows air out of it, i have heard on here somewhere before that that line has something to do with not allowing the fuel to travell out the tank till the engine starts spinning but i thought about puttin the section to join the pipes together but themn with the 1 pipe blowing out air thought well thats just gonna blow air back sending the fuel back into the tank rather than suck it out..... i dunno i know the kat has 2 lines for a stupid reason to do with fuel flow just cant remember what it was and its tickin me off cus i dunno how to solve it..... and its the only thing left stopping the bike from finally firing up :: is there no reads on here about how the gsx600f carbs work with these lines

[The CyberPoet]

The petcock for all the 88-06 Kats has a vacuum connection that opens a diaphram to allow fuel to flow in the ON and RES positions (the diaphram gets by-passed in PRIME). The vacuum coming through the hose from the engine (carb vacuum nipple on the 98+, something similar on the pre-98's) pulls the diaphram open against a spring to permit fuel flow; when the engine is shut off, the spring behind the diaphram pushes it sealed/closed again.

Most of the pre-98 petcocks should have three connectors -- two fuel connectors and one vacuum connector. The fuel connectors always exit to the left and right of the dial, and the vacuum connects to the rear of the petcock (behind the dial).

Suzuki went from a single-fuel-feed-line on the 600's in '88 to a double in 89 or 90, and then back to a single line again starting in '98 ('96 in Europe). The 750 went from double to single in '98 as well ('96 in Europe).

All of these systems use gravity-feed to get the fuel from the tank to the carbs -- the vacuum to the petcock is only to de-activate that safety shut-off diaphram.

Hope that helps.

Cheers,
=-= The CyberPoet

[bigbike-r]

so... as this extra line i have if i leave it not connnected to anything then i should still get fuel to my carbs from the other line...... or is the vacum line not allowing the fuel to run to the engine thus stopping me from getting it to fire up

i guess what im asking is what do i do with this line to get fuel flowing to the carbs and fire the bike up??? do i just leave it unconnected or will it need plumbing in?

[steves]

You need to make sure that both carb lines get fuel, otherwise you'll be fuel starved on 2 of the banks.

[bigbike-r]

so stick a y section in to join the 2 pipes ..... but 1 blows out air??? and didnt cyber say 1 is a vacum to activate the diaphragm shut-off?? so that line wont need fuel will it?

[The CyberPoet]

No, they're saying if the petcock you have only has one fuel output line, put a Y-splitter in that and run it to the two fuel connectors on the carbs. Personally, I would recommend getting the right petcock for the carbs (i.e. a two-fuel-outlet petcock if your carbs have two fuel connections).

DO NOT INTERCONNECT THE VACUUM LINE WITH THE FUEL LINE(S)!


Cheers,
=-= The CyberPoet

[bigbike-r]

but my carbs have 1 fuel line and just that vacum line



so i connect the 1 fuel line and leave the vacum line un connected and this should be suffice

[Black_peter]

[bigbike-r]

oh ok hold on then