gsx750e 1980 Carburator leaking

[Anders74]

Hi!

I have problem with fuel coming out under directly almost when i started the bike. Its not coming true the two hosts.

I ultrasound-washed the carburator and took out all except floats and needle . 

1. Exhanged the four scews  for the float house. 2. Raised the needle to the lowest for more fuel and changed the main jet to 135.  (instructions for open air-filter).

Any idea?

Also wonder about the o-ring that sits under the floating gasket. See images. I see that that o-ring is not on all carburator. Why? You dont need it really? 

Thanks

[Gixer1460]

Two problems (I think) - carb leaking . . . . . from where I am unsure but assume overflow or carb throat. This is generally a stuck float valve or a defective float valve. If you did an ultrasonic clean, why didn't you do the floats, valves etc? ? ? Who's instructions for the MJ and needle change? A 135 is a huge jet for a 750 (which i'm assuming is pretty standard barring maybe an exhaust change?) Unless you set-up on a dyno, jetting changes are largely guesswork! 

If you are a non English speaker - post in native language & someone on here may be able to translate into correct English as Google translate isn't always the best 

[Russ750ET]

Drop the bowls, remove the floats and float needle etc and thoroughly clean. These mechanisms are sensitive to dirt. If you haven't already, fit an inline fuel filter between the tank and carb. Unless you have stripped/treated your tank it is probably full of crud (mine was). 

I believe the o-ring under the gasket it necessary, I have them fitted to each of my carbs.

Bench test the carbs with a dummy tank (worth buying if you dont have one). Saves all the hassle of fitting just to see them leak again.

Gixer1460 - It looks as though he is copying my jetting specs. Which work okay 'ish' on my 750 which is heavily ported, different cams, pod filters and a 4-1 exhaust with a very short 60mm race can. It will probably be too rich for Anders but it will be a learning experience in the dark art of jetting 

[Anders74]

46 minutes ago, Gixer1460 said:

Two problems (I think) - carb leaking . . . . . from where I am unsure but assume overflow or carb throat. This is generally a stuck float valve or a defective float valve. If you did an ultrasonic clean, why didn't you do the floats, valves etc? ? ? Who's instructions for the MJ and needle change? A 135 is a huge jet for a 750 (which i'm assuming is pretty standard barring maybe an exhaust change?) Unless you set-up on a dyno, jetting changes are largely guesswork! 

If you are a non English speaker - post in native language & someone on here may be able to translate into correct English as Google translate isn't always the best 

this guy used that setting:

 

 

 

 

 

[Anders74]

1 minute ago, Russ750ET said:

Drop the bowls, remove the floats and float needle etc and thoroughly clean. These mechanisms are sensitive to dirt. If you haven't already, fit an inline fuel filter between the tank and carb. Unless you have stripped/treated your tank it is probably full of crud (mine was). 

I believe the o-ring under the gasket it necessary, I have them fitted to each of my carbs.

Bench test the carbs with a dummy tank (worth buying if you dont have one). Saves all the hassle of fitting just to see them leak again.

Gixer1460 - It looks as though he is copying my jetting specs. Which work okay 'ish' on my 750 which is heavily ported, different cams, pod filters and a 4-1 exhaust with a very short 60mm race can. It will probably be too rich for Anders but it will be a learning experience in the dark art of jetting 

Aha thats to much for me then!!  Change back i gues to 112,5? :-P

[Anders74]

2 minutes ago, Russ750ET said:

Drop the bowls, remove the floats and float needle etc and thoroughly clean. These mechanisms are sensitive to dirt. If you haven't already, fit an inline fuel filter between the tank and carb. Unless you have stripped/treated your tank it is probably full of crud (mine was). 

I believe the o-ring under the gasket it necessary, I have them fitted to each of my carbs.

Bench test the carbs with a dummy tank (worth buying if you dont have one). Saves all the hassle of fitting just to see them leak again.

Gixer1460 - It looks as though he is copying my jetting specs. Which work okay 'ish' on my 750 which is heavily ported, different cams, pod filters and a 4-1 exhaust with a very short 60mm race can. It will probably be too rich for Anders but it will be a learning experience in the dark art of jetting 

Thanks for answer! So best for me with open air filter to just use 112,5 jet and maby still have the needle andjustment?

[Russ750ET]

You will likely need richer mains, but maybe not as much as 135.

I wouldn't like to say exactly, maybe 120/125?

Try both 112.5 and 135 (if you have them already), and see how the bike reacts.

Jetting without a dyno is a lot of trial and error. Do lots of reading up on lean/rich conditions at different throttle openings etc. I found it actually helps to get it wrong, both lean and rich, so that you can identify and understand lean/rich conditions.

[Anders74]

2 hours ago, Russ750ET said:

You will likely need richer mains, but maybe not as much as 135.

I wouldn't like to say exactly, maybe 120/125?

Try both 112.5 and 135 (if you have them already), and see how the bike reacts.

Jetting without a dyno is a lot of trial and error. Do lots of reading up on lean/rich conditions at different throttle openings etc. I found it actually helps to get it wrong, both lean and rich, so that you can identify and understand lean/rich conditions.

 

2 hours ago, Russ750ET said:

You will likely need richer mains, but maybe not as much as 135.

I wouldn't like to say exactly, maybe 120/125?

Try both 112.5 and 135 (if you have them already), and see how the bike reacts.

Jetting without a dyno is a lot of trial and error. Do lots of reading up on lean/rich conditions at different throttle openings etc. I found it actually helps to get it wrong, both lean and rich, so that you can identify and understand lean/rich conditions.

How much does it do to change the needle to sit higher upp? (cap level on the lowest) ??

[Russ750ET]

Your clip position will impact the 1/4-3/4. If you are currently on #3 and its lean, try going to #4

Charts like this help to visualise it a bit better

 

Edited October 27 by Russ750ET

[Dezza]

Seeing as they're BS carbs, maybe try and find a (LeDar) air corrector kit (grumpy was selling similar a while back). One of the greatest inventions known to humanity .

[Anders74]

16 hours ago, Russ750ET said:

Your clip position will impact the 1/4-3/4. If you are currently on #3 and its lean, try going to #4

Charts like this help to visualise it a bit better

 

Great image!!! Thanks

[Anders74]

6 hours ago, Dezza said:

Seeing as they're BS carbs, maybe try and find a (LeDar) air corrector kit (grumpy was selling similar a while back). One of the greatest inventions known to humanity .

Thanks! So how much did you change the main jet with that?

Edited October 28 by Anders74

[Anders74]

22 hours ago, Gixer1460 said:

Two problems (I think) - carb leaking . . . . . from where I am unsure but assume overflow or carb throat. This is generally a stuck float valve or a defective float valve. If you did an ultrasonic clean, why didn't you do the floats, valves etc? ? ? Who's instructions for the MJ and needle change? A 135 is a huge jet for a 750 (which i'm assuming is pretty standard barring maybe an exhaust change?) Unless you set-up on a dyno, jetting changes are largely guesswork! 

If you are a non English speaker - post in native language & someone on here may be able to translate into correct English as Google translate isn't always the best 

the floats was in the carb during the wash! mm I understand now that 135 is to much! I try again with just 112,5. One main jet was really dirty.