'82 GS400E Carb Issues (Help)

[Guest]

Hi,

I recently purchased an 82 GS400E and have been having some carb trouble. If possible I would appreciate what feedback I can

1. After fully cleaning the carbs I noticed that when I primed them fuel was overflowing into my air box. Should be an easy fix and will just get a new set of float needles/seats. I verified this by removing the carb, cleaning the needle and seat, then trying to test bowl fuel level and the fuel would go higher than the top of the carb. In my mind this means that the needle is not sealing to stop the flow of fuel. I noticed that some other brands use a rubber tip on the needle, is there merit to using a different type of just get an OEM replacement kit?

2. I noticed that when I would pull out the choke it would not stay (have to hold it or it slides back in). Looking through some manuals and online I believe I found out what is missing but do not know where to find them (parts 15 and 16 attached. Any assistance finding a source for these pasts would be greatly appreciated.

Thank you so much and kindest regards,
-Ian

[tom203]

Welcome. Most of float needles that I have seen have not been rubber tipped. There's likely to be a gasket or o-ring around seat- these often dry out and give the appearance of a leaky needle, so pull the seats out and check .The float needles can get small grooves worn in them.
I can't quite make out the missing choke parts, but someone else will shortly.

[ianryeng]

Hi Tom,

Thank you for the quick response.
So there should be a rubber seal inside the brass seat to seal the float needle?
That definitely would make more sense than metal into brass which is how I got it.
Will take a look for replacement seals.

The choke parts are a spring and ball but I cannot find any reference to part numbers or dimensions to source a replacement.

Thank you again for the quick reply and feedback.

Kindest regards,
-Ian

[MOC]

what are your float heights set to? are you dripping out of only 1 carb, or both? is it only when the bike is on a kickstand? or on the center stand as well?

[ianryeng]

Hi

My floats are both set to 22.4 mm which I believe is the correct height for the bike. Both of the carbs overflowing and not restricting fuel level. When bench testing the floats fuel will flow up the tubes (connected to the bowl drain) to meet the fuel source. The fuel level can get over the top of the carb in the tubes and starts running out of the airbox and engine interface orfaces. While I cannot see any debris in the float valve the float needle has a slight groove from wear. The O-ring is sealing proplerly and is greased with silicone valve sealant. The floats are a plastic type but appear to be in excellent condition with no obvious issues.

I first noticed it when I tried to start the bike after cleaning the carbs (never started before I cleaned them) and set the tank to prime. I could hear fuel running into the airbox which then ran out the airbox drain. The bike would run but only at high rpm and would not idle (clearly this is part of the reason).

I really appreciate the help and feedback from everyone. I ordered new float valve assebmlies (float needles and seats) and am hoping that it will resolve the issue. Hoping to get the parts before the weekend but if anyone thinks that something else may be wrong I would appreciate the feedback.

Thank you so much.
-Ian

[GS(X)400]

The parts u need you can get from the susuki dealer most likely

http://www.cmsnl.com/suzuki-gsx400-1982-ez_model13618/partslist/?model_q=gsx400

Look them up here are call your local for them.

Also I sent u a message on the gtamotorcycle form as I am interested in buying the spare seat u have with that parts bike you got. Hit me up here or there if your interested

[GS(X)400]

PS i cant realy see what parts you want on that tiny diagram. Can you post a pic up from your carbs and point them out..Or can u identify them on the link i provided?

[Mekanix]

Ball PN 13596-93010

Spring PN 13434-43010

Same parts from 1981 on, Just find someone selling those part numbers

So anyone with a gs400x from 81 to 88 should have the same carbs and those two pieces.

Contact Jfman. he has a bike being parted out and might sell the whole carb set.

http://www.thegsresources.com/_forum/showthread.php?t=200892

[ianryeng]

Hi,

Thank you for all the feedback and I really appreciate the part numbers for the choke parts . I found some ball bearings and a random spring that I stuck in there for now which are working but the spring is too soft for the long run.

I installed new float valves from 'parts 'n more' and installed passage plugs which were not installed in the carb when I purchased the bike. I installed new o-rings between the boots and the engine. The rubber boots look to be in good condition with no cracks. I put new worm gear style clamps on both sides of the carb since the original ones were bottomed out. Also installed new vac line between the petcock and carb which is sealed with Dow 111 valve sealant to ensure it is not leaking.

The good news is I believe the the floats are now working properly because I can start the bike full choke and it will idle ~1100 rpm which it would not before.

The bad news is I still seem to have a vac leak and cannot locate the source. The bike will idle with full choke until the engine warms up. If I try to rev the throttle it will stall, if I try to push in the choke at all it will stall (even after idling for 15+ minutes). After it has fully warmed up the engine will randomly rev between 1500 and 5000 rpm (constantly changing irregularly) but will stall if I try to move the throttle. Spraying carb cleaner on the engine side, airbox side, and fuel T does not seem to indicate any of these are the source of the leak. I can coax the engine back to idle using the choke and it will stay there suggesting the leak is not constant making it even harder to find the source.

If anyone has any other ideas for what could be causing the issue I would really appreciate it as I am not sure what to try next...

Thank you all again for the feedback and I truly appreciate the help.

[pete]

My suggestion is the intake books from carbs to head.

I know you say they look to be in good condition, but the tell tale sign for me that they're not is that you also say the stock clamps are bottomed out.

I had the exact same thing on mine, and what happens is that they shrink with age. Mine appeared to seal well, but clamps bottomed out, and it was very difficult getting the carbs installed and using rubber grease helped them in.

Even with new O rings I still had vacuum leaks.

I got new boots for about $US50 and the difference was amazing... carbs slid straight in and the stock clamps had plenty of bite to seal without bottoming out.

No more vacuum leaks...

[GS(X)400]

Yup what pete said.

Pipe, Intake Rh Gsx400 1982 - 13110-44200
Pipe, Intake Lh Gsx400 1982 - : 13120-44200
Oring for each - 09280-34004

I could not get these parts from a susuki dealer if i remember correctly. I ordered then from ttp://www.cmsnl.com but that took 2 months and a tone of postage so put in a big order to make it worth your while . So ask suzuki before you do and check ebay/other suppliers.

I also am also planning to replace the airbox side ones as well.

[ianryeng]

Thank you for the feedback.
I will order replacements soon.

Just tried starting it and noticed that it only seems to be running on one cylinder (only the right cylinder warms up). Will pull the left plug and see if it is firing and check that the cylinder has compression.
Not what I was expecting to find as what I wanted to test was running it on prime with the vac port on the carb blocked off to rule out the petcock.

UPDATE:
Both spark plugs are firing and both cylinders appear to have compression.
When it was running the 'exhaust' from the left cylinder was cold.
Plugs appear to be rich but the bike still stalls when the choke is less than fully open.

[GS(X)400]

Sounds like you might have a leaky petcock. You can order a direct replacement from suzi (Or rebuild but I would not go that route)

[ianryeng]

You may be correct about the petcock but definitely not the only issue.
When I noticed the single cylinder running I had the vac inlet on the carb blocked and the tank set to prime.

I borrowed an ultrasonic cleaner from a friend and will be pulling the carbs to perform another cleaning to rule them out as the reason for the left cylinder not running. I have spark and compression so if it persists I will have to start looking at the valves. What I am wondering is if my hunting idle I had experienced was the right cylinder kicking in and out but can't be sure.

Will let you know what I find and appreicate all the support.

Kindest regards,
-Ian

[ianryeng]

Problem Solved! (mostly)

Hi,

So when I purchased the bike there were two 'barbs' which face each other which directly route to the fuel in the float bowl. Having these open didn't make sense (and still doesnt) since it will allow contaminants to get into the bowls. Looking at some exploded parts diagrams I see a tube that would connect the two and used some 1/4" line to tie them together.

Took it off in a test and everything worked great. No racing throttle, no leaks, no issues. After doing some reading there was a mention that your float bowls must be at atmospheric pressure. Now my concern is what is supposed to tie these together and how do you ensure filtered air gets there to equalize the floats to atmosphere?

I have a picture showing the area I am unsure of.


Can someone help me figure out what is missing and how I ensure crud does not get sucked into the float bowls through here?

Thank you so much
~Ian