Gsxr 400 pissing petrol out of carb float bowls.

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slowest
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Gsxr 400 pissing petrol out of carb float bowls.

Post by slowest » Wed Oct 30, 2019 9:34 am

Hi everyone.

I have gsxr 400 GK73a that i am busy restoring and is also my daily driver. Tge bike does have gsf 400 bandit carbs on then but they were never a problem for 2 years until recently.

Ok one morning, i went to start my bike as i have to go to work and also have to take the misses to work. The bike didnt want to start.

So i took the tank and the airbox of and checked if i couldnt find the problem and then i found
Quite a bit of petrol just chillin in front of the carb butterfly. So obviously my first thought was if i turned the throttle the butterfly would open and empty the petrol into the cylinder, which is a bad idea obviously. So tried fixing it but eversince i started everything just went downhill.

So i initially fixed the problem and the bike purrrrrrrrred like a kitten, but then one morning when i went to start the bikr again, petrol was seeping from the float bowl gasket area.

So what i have done so far.
- new floats
- new orings (dont know if they are the correct sizes, i tried test fitting)
- adjsuted floats to 14.6mm which are as per manual
- got new float valves (they were cheap as hell, and i thought they could also be the problem so i ordered new ones from "keyster")
- cleaned and synced the carbs more than once.

I still think this problem is the symptoms of a stuck needle as the problem is never with the same carb its also a different carb that leaks after i took the carbs apart to double check everything or sometimes its the entire bank of carbs that leaks. Now i have done some research and saw that a few people actually polish the needle seat but the problem is, my bikes needle seat is plastic so can anyone recommend a way to polish these as mine has quite a bit of varnish on them.

I also thought that maybe something was stuck in the seat of the float neelde but everything is clean.

This is definitely the symptoms of a stuck float.

Any ideas and help would be appreciated.

Thanks in advance.

I also ordered some new keyster needles and carb o-rings so going to fit those when i have spare time next week.

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moforockband
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Re: Gsxr 400 pissing petrol out of carb float bowls.

Post by moforockband » Fri Nov 01, 2019 9:51 am

As the carbs are 30 years old, most of the gaskets parts are finished/and all need replacing. The float bowl leak could well be an old carb bowl gasket.
I rebuilt mine with a viton kit, and OEM gasket parts. (cost around £100 all in), and they have been faultless, and do not leak.
As long as the floats are set within 0.5mm, you can leave them alone.

slowest
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Re: Gsxr 400 pissing petrol out of carb float bowls.

Post by slowest » Fri Nov 01, 2019 10:39 am

moforockband wrote:As the carbs are 30 years old, most of the gaskets parts are finished/and all need replacing. The float bowl leak could well be an old carb bowl gasket.
I rebuilt mine with a viton kit, and OEM gasket parts. (cost around £100 all in), and they have been faultless, and do not leak.
As long as the floats are set within 0.5mm, you can leave them alone.
I have changed the float bowl gasket and it still leaks, i have cleaned these carb numerous times and also replaced the o rings (not viton, nitrile) also i could not find the right sizes for the o rings so i just fitted o-rings with trail and error. But i think the oring are to big as they are bulding the float assemblies and the float assemblies also doesnt stick to the carbs with these orings.

But i did order and receive new float needles with the correct sized o-rings. So i am going to fit them next week. I just hope that will fix the problem.

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LiteTekBlair
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Re: Gsxr 400 pissing petrol out of carb float bowls.

Post by LiteTekBlair » Sun Nov 03, 2019 2:08 am

https://litetek.co/Carb_Kit_Suzuki_GSXR400_GK73A.html
Shameless plug I know but just trying to help. Our float bowl seals are now made from Flourosilicone which we have tested and found to be an excellent choice.
Cheers
Blair
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Carb seal kits in viton & other parts
https://litetek.co

slowest
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Re: Gsxr 400 pissing petrol out of carb float bowls.

Post by slowest » Sun Nov 03, 2019 4:52 am

Hi blair. How much are those? Also i have read that those gaskets arent suppose to stop fuel. I also bought new gaskets and yet that did not solve the problem

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slowest
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Re: Gsxr 400 pissing petrol out of carb float bowls.

Post by slowest » Tue Nov 05, 2019 3:42 pm

Ok so. Float needles and new gaskets are installed also used the correct size o rings and got the float height set per manual to 14.6 mm and no more leaking from carbs but. . . . .

Problem now is the bike runs waaaaay to lean. I even set the floats to 15mm and yet its still to lean.

My plugs are literally pure white, but it was light brown before i installed new float needles.

Any ideas?

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Re: Gsxr 400 pissing petrol out of carb float bowls.

Post by LiteTekBlair » Wed Nov 06, 2019 12:28 am

Most people have no idea at all of how to read spark plugs. First, it is done with new plugs, and most of the insulator will be white. The mixture is read at the bottom where the insulator meets the threaded surround.
http://www.crankshaftcoalition.com/wiki ... park_plugs
Carb seal kits in viton & other parts
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Suzuki416
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Re: Gsxr 400 pissing petrol out of carb float bowls.

Post by Suzuki416 » Sat Nov 09, 2019 8:34 am

slowest wrote:
Tue Nov 05, 2019 3:42 pm
Ok so. Float needles and new gaskets are installed also used the correct size o rings and got the float height set per manual to 14.6 mm and no more leaking from carbs but. . . . .

Problem now is the bike runs waaaaay to lean. I even set the floats to 15mm and yet its still to lean.

My plugs are literally pure white, but it was light brown before i installed new float needles.

Any ideas?

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How does it run?

If you really want to know then take it to a dyno - but tell him first you think its lean>


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