ok i got this bike. 92 katana gsx600f model j it came in pieces no big deal missing some things here and the still no problem i cleaned the carbs and noticed there are 4 fuel lines and i have a send and return for the gas tank only 2 lines. Now the lines that come from the carbs are as follows on the 2 left carbs there is a T fitting on the bottom of the carb between the two of them, that is where one line is also there is another T fitting on the top of the carb comnnecting between the two which makes the second line and the same for the two right carbs which make four lines now im pretty sure that the top lines are the return and the bottom are the send (pretty sure correct me if im wrong please) basically my question is am i missing some t fittings to connect them together to make 2 lines or what. and also just so i kknow where does the send and return lines connect to the gas tank? (front /back hookups on the petcock)(sitting on the bike) thank you in advance.
First thing is to identify the fuel supply line. This is usually the largest...about 15mm dia... and goes to the carb feed rail nipple...mine is between 1 and 2 then back to the fuel valve.
Then you will have a smaller pipe which provides vacuum to the fuel valve. On my bike this was 'T'd in with another pipe which also provided vacuum for the pair valve...since removed, (I simply lengthened it and fitted it to my fuel valve direct), there should be a small nipple at the rear or side of the fuel valve for this fit on.
The other two may be breather hoses if they fit between the carb banks via a T fitting. Both of mine are toast so I got rid of them.
Any pipes left over may have been fitted for carb syncronisation and usually will be fitted to a small nipple just to the side of the carb near the cylinder head manifold end. This is a direct opening to the air/fuel passage so vacuum from the motor can be measured when syncing the carbs. These pipes...3 to 4mm dia... have to be sealed and I used a small tightly fitting screw on the ones I fitted.
I just re read your post and the two bottom lines may be an equalising pipe for the float bowels of the carbs. The top ones sound like breathers as mentioned above. I would fit the carb fuel line set the tap to prime ...if available and see what comes out of the lower pipes. If it is fuel then I would suspect they are as stated.
thank you tha was a little complicated i found a tread somewhere else tha had a perfect explanation "The bottom to T's are you fuel delivery the fill your bowls with gasoline. The top to T's are vent hoses they connect to nothing...just rout out to fresh air with these. your petcock is on the left side of the tank...as sitting on the bike the left fuel line (the lower left "T" Between 1 and 2) connects towards the back of the bike the fuel line on the right (between 3 and 4) connects on the front of the petcock. about the vacuum line... right hand side (faceing outward very easy to see if you have the fairings off.) towards the front of carb 4 should have a line running from the the the back side of your petcock. your petcock when looked at from abot makes a sideways T (as sitting on the bike) The front line connected to carb 3 and 4. the middle one that faces the right side of the bike should be the vacuum going to the outer side of carb 4 right under and behing the the choke rail. the fuel line from carbs 1 and 2 should connect to the petcock facing the rear of the bike.