Hello,

Pulled the tank lastnight and PO did not have any lines hooked up.

Does anyone know where this fuel / vent line go?

Also found this electrical connection apart, is it a tip over sensor? Any idea where it mounts?

Thank you,

Barry

Hi, I'm afraid that I can't help you with the electrical matter but that hose looks to me to be the drain hose which gets any water/fuel overspill away from the hot engine. It should attach to the metal pipe which runs through the petrol tank and it routes the water etc down to exit just ahead of your right foot. There are generally about three different hoses which exit at the same point, including one from the battery and one from the airbox. Good luck!

The tank is missing the hose coming off of that vent tube on the bottom of the tank, I will install the line in the photo onto the vent tube and route it out to the bottom right of the motor.

I figured out the electrical, I believe it is a tip over sensor  and actually mounts with 2 tiny screws to the bottom of the carburetors. Of course those 2 tiny screws are long gone from the PO.

Thank you!

that hose contraption is the PAIR system, mounted on a carb bowl it engages a solenoid to change vaccum and affectt  diaphragm position of the carbs, the black box_TCM/cdi control it alongside TPS sensor on the side of the carb(butterfly valve).
Califonia emission requirements if i recall correctly.

you can and should remove it, it will fail or start leaking, plug all the carb ports, they are nice hoses , reuse them dont ditch them

the other long hose seem to be the tank drainage for the rain, run a long zip tie or something to unclog it to be safe (Through tank and hose)

Hey @Armandorf, by remove it can I just disconnect the electrical connector to it?

Also do you happen to know how the routing goes for the hoses off of the metal cylinder thing mounted to the frame with 2 bolts (left side in photo), the round black canister mounted with 1 bolt (right side in photo) and where the 3/8th short hose goes to?

EDIT... so I pulled off everything that is in the photo below. I got the bike to fire up for the first time today but it has a very high idle. I tried turning out the idle screw (currently around 6 turns out) still high. Even though I plugged the 2 vacuum ports on the front side of the carbs, I might have a vacuum leak somewhere?

Thank you!!

you have to plug the white plastic above each diaphragm(carb top cover)
also the two ports for synching that are around the air entrance(butterfly)
with that should be 4 ports blocked.

Well, the left synch port goes to the fuel petcock for ON position so there will be 3 port blocked.
check the petcock.
Fuel valve/petcock fails and ruins with vaccum leaks for the automatic function (ON position on fuel valve/petcock), sometimes leaking fuel or air and ruins carburation.
maybe better to test it with all 4 ports blocked and in prime. then you connect the vaccum petcock line for ON position,(you can use the hoses removed from the PAIR system)

the electrical thing messes with vaccum to lower diaphragms, and uses TPS(throttle position) to activate it via the black box(igniter/cdi/tci)
you can disconnect that. search for pair removal if in doubt.

Frame mounted things you remove that are part of PAIR system::
LEFT CylindricaL=PAIR something,
RIGHT plastic frame mounted canister also

suppose they trap fumes or something. you can remove both things that are mounted to the frame

Carbs have 3 hoses, seeing it from bottom to top(carb bowls to diaphragm covers):
1 lower for fuel,
2 middle for vent
3 up with the black plastic canister with a hose to a T joint that connect both diaphargm top covers with foam inside for filtering, dont remove it.

the middle T connection(2) is the vent hose and goes to the back of the bike and sits over the airbox
for hose routing there are some pictures in other threads or service manual https://gstwins.com/gsboard/index.php/topic,74300.msg889207.html#msg889207

@Armandorf, I used small vacuum plugs to plug the 2 vents (white caps) on the front side of the carbs. I also placed a hose on one of the side ports that goes to the petcock for vacuum. The other carb has that one plugged from factory by the looks of it.

Would you suggest putting a rebuild kit into the fuel petcock to ensure ON and PRIM are sealed and not allowing air inside the system?

I did remove the black canister but I left the metal (2bolt) box thing on the frame. It has a line that goes to the bottom of the airbox... can I remove this line from the airbox ?

Also, I am slightly confused on which T you mentioned at the end of your post. The diagram in the other thread you sent is a bit confusing to me. Do I need to reinstall some of the lines I pulled out that I showed in the previous photo?

I will send a photo later today of a top view of the motor for how things are currently looking.

Thank you, I appreciate your help!

You could leave the shiny metal thing connected, doesnt make much difference i suppose. it doesnt mess with carbs directly.

Look at 2
@herennow
Are these the ports we were talking here??: https://gstwins.com/gsboard/index.php/topic,74300.msg889206.html#msg889206

@Armandorf, so I went back out lastnight and I made sure the 4 ports you were talking about are capped off properly. I also added some more fresh fuel, removed the tank and fuel lines, put an inline filter in and rerouted one of the fuel lines. I made sure the lines were getting full flow from the tank to the petcock.

I fired up the bike after adjusting the idle screw underneath and it idled half decent, then died. I fired it back up and it idled low so I started turning up the choke and it operated as it should. As the bike warmed up I started decreasing choke and at the end of it the bike sat and idled. I hit the throttle for the first time and it revved up and dropped back down perfectly.

Also the tach was stuck at 0 and not moving but once I hit the throttle for the first time it flew up and back down and sat at idle. So that was an easy fix haha

Keep in mind this bike last ran years ago, and probably hasnt been started in a long time. I think it spent its last 2 or so years in a seacan 

Thank you for the help, it was greatly appreciated and im happy to be rid of all that extra crap from the top and bottom of the motor.

I kept the vacuum lines because you mentioned they were in good shape however im not sure what im going to use them for now?

Before and after photos...

Nice, you only need to take care of the petcock. Beware that leaving it in prime can flood carbs, even engine oil if the carb fuel valves fail.
you need to close fuel delivery when engine is shut.

I didnt use the rebuild kit as my petcock is the older model and is dead, i tried this with no success: http://gs-500.info/index.php?title=Benzinhahn_von_Vakuum-_auf_manuellen_Betrieb_umbauen , it worked top convert ti to manual, but no reserve.

@Armandorf Hey! So bike started to run rough and then cut out. I'm figuring carbs because it was running good but then started running rough and then quit.

I pulled the carbs today and have them apart. Definitely alot of gunk to clean out. Also the silver metal box with 2 bolts holding it to the frame, has 2 lines running from it to the front of the cylinders (as in the photos) I can't detach this box or lines due to this? I did plug the vacuum port on the back of this box though. When I removed the carbs I noticed alot of fuel came out of the line that runs from that box to the airbox. Any idea what this could be caused by?

Thank you again!

You should search about the correct PAIR system removal.

you only need the 3 lines i showed earlier to run the carbs.
with a good cleaning it should run right, i would also replace the orings behind the boots on the intake of the valve head.

look for m72 s blog, its in his signature, i also made a post https://gstwins.com/gsboard/index.php/topic,74139.0.html

If I were you, I would start hitting those exhaust retaining screws with some kind of release agent. Do it for several months, and then try to loosen them gently.  Put them back with copious amounts of copper slip....
When I got my back One of those had been broken off by the previous owner.. was a real pain....

@Armandorf I gave the carbs a good cleaning and put everything back together this weekend. The bike now fires right up cold on half choke but once at operating temperatures dies when it idles for longer than a few seconds.
I've messed around with the idle screw (white knob) quite a bit but it hasn't helped much.

Would this point to orings on the intake and valve boots ?

Any other suggestions is appreciated!

Thanks!

You dont need to change intake boots unless they are too hard and cant seal the carbs, the oring is critical.
I had to replace the bolts of the clamps, they were stripped out, maybe by my fear of not sealing i tightened a bit too much...

Even better if you use a impact driver to remove the boot, and replace it with allen bolts.

you can use something flamabble to test for air leaks and you spray around with caution.

or detergent/water dish soap bubble method

+1 I chased funny behaviours for ages on my bike and it tuned out to be a vacuum leak around the o-rings. I did not tighten them enough....

When you have the POP POP POP from the exhaust on engine braking, its a sign.😉

I ordered up a carb rebuild kit off of Amazon, I figure new orings, seals, float bowl gaskets and jets cant hurt compared to the old/varnished pieces that are inside my carbs.

Do you guys think it is imperative to remove the steel lines off of the front of the cylinders (like in my photo above) and install block off blocks or can I leave all of that alone and leave the line going to the bottom of the airbox open ?

Also, along with it stalling out on idle, it does has a quiet "pop,pop,pop" when it is idling. I will replace them regardless because even though there is only 5,000km on the bike, I'm sure they are hard and crusty from sitting.

Would the o-ring that you are referring to, would that be #19 ?

@Armandorf, which brass plug is the mixture screw sitting behind? If you could label the jets in the photo it would help me and I'm sure many others.

Thank you again!!

The parts diagrams can be found here.  Click on the section that contains the area you are looking at.

https://www.cmsnl.com/suzuki-gs500f-2008-k8-usa-e03_model34238/partslist/

The top screw that is deeper in the "tube", close to the edge.
You can also see the passage on the inside of the carb

Quote from: Armandorf on May 22, 2024, 10:50:28 AMThe top screw that is deeper in the "tube", close to the edge.
You can also see the passage on the inside of the carb

You removed the "cap" to expose the brass slotted screw (circled in red in the photo)?

Also for the PAIR, if I do not remove the lines from the cylinders and install blocks, can I just cap off the tube running from the silver box (mounted on the frame) to the airbox ? Right now I have this tube connected to the airbox and am wondering if this could be causing issues with how the bike idles?

Thank you!