[baretree]

I have a 1988 GSX600F Katana which I cannot seem to work out the carb issues on.

I completely disassembled the carbs, cleaned and reassembled them over the winter. I am absolutely sure there are no parts left out as I did this in a relatively sterile environment with parts carecully laid out and numbered.

When I hooked the carbs back up, they ran good for awhile and I syncronised them using a home made manonmeter setup. I also rode the bike for approx one week and 400 miles with good performance.

I decided to resyncronise them and after removing the airbox, I noticed that two carbs were spouting fuel evertime I turned the stopcock on. I am aware of the vacuum diaphram in the stopcock, mine is damaged so I installed another stopcock in series witht he original.

Here's the nexus question. If you flow fuel to these carbs, do the needle valves in the float chamber stop the flow when the chamber is full or will they continue to spout fuel even though the bowls are full

I also have replaced the vacuum diaphrams on the top of each carb with newer ones, but I set the stops on the needle valves identical to the way they were before.

I assume it will take someone who had been through the same thing with these carbs to accurately answer this.

Maybe they are supposed to leak fuel constantly and thats what the vacuum diaphram in the stopcock is for.

Thanks in advance and I will post any sucesses.

HELPPPPPPPPPPP!!!!!!!!!

UPDATE ---------

I disassembled all the carbs. I set the float height very carefully. I hooked each carb up individually to the gas tank to see if it would leak. None of them did. I reassembled the entire assembly and hooked it up to the fuel tank to check for leakeage. No leakage. I installed the carb assembly back on the bike and hooked it up to the fuel tank, turned on the fuel to check for leakage. No leakage.

I then tried to start the bike. It fired and then quit. Immediately the carbs began leaking gas out the intake side through the small holes on all four carbs. Now when ever I turn on the fuel, all four carbs pour fuel out the small holes on the intake (airbox) side.

I have done everything correctly at least 15 times and this still leaks fuel like a Kuwaiti oil well with Sadamm at the valve. I am stumped like I have never been before. I am so mad I want to burn the bike in the backyard.

Please help I am absolutely stumped!!!!!

Attached is a photo showing the holes (small hole at bottom of intake side)
that are pouring the fuel.

 

[Phease]

The way it works is that when the engine is turned on a vacuum is pulled and the diaphragm shifts to one side allowing fuel to pass from the tank to the carbs, which is why if you have your petcock set on prime fuel flows whenever but when set at normal or reserve no fuel should spill from the fuel tank. So if the vacuum valve is knacked then fuel will pour constantly, it seems as if it is sticking if it is ok when you reassembled the bike but then after starting the engine pulling an initial vacuum they don't return to the original position when stopped. Try replacing the petcock at the base of the fuel tank where the vacuum is pulled to let fuel out.

Hope you get the bike right soon.

 

[dirtyfingers]

Yes, fuel flow is supposed to stop once the needle valves are pushed against their seat by the floats, regardless of the stopcocks operation. I've rebuilt hundreds of carbs, and in my opinion you are in need of some new needle valves. The rubber tips go bad. Also, I think that you r carbs have a white/yellow plastic carrier that house the needle seat, float and a jet, right? Replace the o-rings on that as well.

 

[baretree]

Thanks!!!

Guys:

I'm getting closer to the issue. Thanks so much for you assistance.
I finally got the bike to run tonight. It appeared to be a combination of float adjustment, fileter cleaning and idle jet debris.

I'm still adjusting using a manometer but I'm definitly closer to home.

Thanks and I will keep you posted.

Thank you so much!!!!!!

 

[baretree]

Thank You both for your help

Dirty Fingers / Phease :

Thank you both for your help. Your advice was correct and following the steps you both outlined, my bike is running better and faster than it has since I've had it.

THANK YOU BOTH FOR TAKING THE TIME TO HELP!!!!!!!!

IT MADE ALL THE DIFFERENCE!!!!!!!!!!!!!!!

 

[badkfive]

i have 88 600 katana i have no idea where vacuum hoses etc. are supossed to be. it has 1 from petcock to carbs and one from petcock to just behind carb 2 where or what am i missisng. the bike will run for a nfewn min. before sputtering to nothing

 

[markew]

i dont get it. you said that in your bench test the float bowls did not leak ie the stop valve2 were working... so how did you solve the back leak out of the idle air bleed jet