New Member - GSX 750E 1981

[Mat46]

Hallo friends,
My name is Christos, I am 28 years old and I come from Athens - Greece.
My unkle has a suzi GSX 750 1981 from the time he was around 25 years old. I was always dreaming to take this bike on the road but at that time i was a bit young. Now , around 10 years later, i have the opportunity to make this dream come true.
The bike was sitting in the garage all these years and the last time i heard shes exhaust singing was 6 years ago.
One day , while we were drinking coffee i asked him if a could make this bike run again. I ride a KTM - a had a TSR before that - a scooter and a KAWA EN500 (fathers bike) and i really like to put my hands on them in modification and mechanical terms.
SO far :
I took almost everything that needs to be replaced out. The bike needs a bit of work but i really want to do this and i also have no time line.
FIRST of all i had to be sure that the bike runs before i stard spending money. After a lot of search in the internet i managed to find a used 4 mikuni carb from the ebay and do all the proper connections (airbox and vent/fuel hoses).
I managed to bring this beast into life but a faced a small prob.
Although the bike idles fine, only the first two (counting from left to right) cylinders run. I figured that out from the exhaust pipes and the sparks.
First job, was to check the elctric part. I tested the sparkplugs and i saw that all 4 bring electricity. So i suppose that this part is ok. When i took the carbs out i figured that the the 3rd and 4th carb rubbers were toaly dry. So something goes wrong and the 3rd & 4th carb do not send fuel in the cylinders. I took them home for cleaning. Tommorow i will put them back and try again to see if they will work properbly.
I would like to hear your opinion if there is something else that i should check.
I forgot to say that when i hit the throttle from idle to mids and bike dies.

Thank you very much and i am waiting for your help cause i am a bit young for this lady

[KEITH KRAUSE]

Fuel starvation for sure.
I'd clean the carbs out as you said, every passage and jet carefully.
Be sure the air filter is clean and all airbox seals are good.
Let us know how it runs.

[Mat46]

Hallo Keith,
Thank you for your reply. I took out the carbs for cleaning and i noticed that the rubbers from cylinders 3 & 4 were totally dry. So fuel starvation was the prob for sure. I took the carbs home for cleaning. All 4 bowls were out, cleaning main fuel jets and passage hoses. The only prob is that i could take the pilot jets out. I tried to unscrew a couple of them but i noticed that if i go harder with the screwdriver i would probably destroy the jets. So i took a needle and cleaned their passage as much as i could. Replaced the old screws and put everything back in order. Next morning i went again to the garage. The bike idles fine and i also noticed that all four exhaust pipes burn the same. Hiting the throttle, the bike responses immediately, however if i hold the revs steady at the midlerange and try to reach high revs the bike does again the same thing. It is likely to go dead. I am not sure if this is again from the carb or i does this because it has almost 7 years to run and needs some road speed to clean out.
What about the screws that are on top of each carb?
Are these air mixture screws? I set them to 2 & 1/2 turns out.

Thank you

[KEITH KRAUSE]

You need to be sure enough fuel is available to all 4 cylinders.
Prime the carbs fully (on the centerstand) and then loosen the bowl drain screws and collect the fuel from each and compare the amounts. They should be even. I can't describe how much should be in the bowls but the amount should be enough to fill the bowls to the point where the bowl meets the carb body. Of course, you have to allow for how much volume the floats take up. There's a measuring tool that uses a clear hose to check the proper level.
After cranking, verify that fuel is in each cylinder.
The rubber manifolds, between the carbs and the head, must be in good condition and any o-rings they may have inside them. Clamps must be tight.
Be sure any float bowl vent lines are clear and not kinked. Route them under the seat.
Be sure the petcock vacuum line is in good condition.
Be sure the air filter is clean and the airbox sealed well. This bike is stock intake, correct?
The mixture screws should be OK at 2 1/2 turns out, that's close enough for testing purposes.
If all this checks OK and it still won't accept full throttle, then I would re-clean the carbs, inspect all diaphragms and o-rings, verify jet sizes, check float levels...in other words, a complete check or possible rebuild.
Sitting dry for 6 years is bad for the carbs.