Questions about carb cleaning

[BikerBoy]

Hey so I have a 2008 gs500f. I got it last year, last owner let it sit a lot but its in good shape overall. First ride of the year last week I put in some carb cleaning mix-in solution with gasoline and ran the bike about 75 miles for 90 minutes on the highway when the darn bike died on me. I would start it up again where it would idle but died everytime I gave it gas, took the choke off, or idled it longer than 30 seconds. Did that for a couple hours til it started going for a mile again then died once more and then AAA showed up.

From what Ive deduced by reading online its a clogged pilot jet. Do you think this could be the problem? Where is the pilot jet anyway, most of these online guides dont have great pictures.

Anyway I took the bike apart and got the carbs out. But do I really need to replace anything on a bike thats only 10 years old? A lot of these guides want you to rebuild and rejet everything whereas I'd rather not fix something that isnt broken especially on a bike thats so relatively new. So for a 2008 gs500 with only 5000 miles what do I really need to replace in the carbs? I can just clean it out if the rubber looks good right?

Also in this attached picture of the carbs, youll notice the black rubber valve connecting the metal parts is completely off of the valve. What does this rubber piece do, and could this be the cause of my bike not functioning properly? I couldve knocked it out while taking the carbs out. https://i.imgur.com/0Q65hBj.jpg

One more question - there are 2 hoses/connectors on the bottom of the airbox, but only one of them was actually plugged into the airbox (the other one was disconnected) Might this be causing my problem? Or is one supposed to be disconnected from the airbox?

Thank you!

[gregjet]

Not sure what rubber bit you are talking about, but that black T piece is the fuel inlet...

[BikerBoy]

Not sure what rubber bit you are talking about, but that black T piece is the fuel inlet...

Yeah the plastic piece, shouldnt have said rubber. You can see the left carb is completely on while the other one is off. Again Im not sure if it was like this when the problem started or if it happened while roughhousing with it during disassembly.

Some other alarms I got while disassembly were, again one of the bottom airbox lines being disconnected, the left carb (the one with the fuel intake connected) had to be drained substantially before I took the carb off - Im talking 3 carb-cleaner caps full of gas, while the right one "only" had 1.5 caps of gas, and also, the left rubber intake manifold was so loose I didnt even have to unscrew the metal o-ring around it (though I did pull on it for 10 minutes before realizing theres a screw there  )

Now that I mention all the problems just with disassembly, it sounds like my problem wasnt with the carbs being dirty at all  Just that everything wasnt connected properly. Ill give the carbs a quick cleaning since its all torn down now..

do you guys think that these conditions were creating my issue?

[max]

I'll leave any diagnosing to those with more experience, but from what I've gathered from my little experience with carbs it's that you're better off just doing the full carb servicing job from the start rather than changing single components and attempting to fault find, which inevitably leads to taking them on and off many times and often takes longer.

In my marked up image of the carbs, the T connector and hose in the back circled in red is the fuel inlet.

The black T circled in yellow that you're asking about should connect to a carb vent hose. I could be wrong, but not having it connected shouldn't effect the performance, but if fuel overflows through it then it'll just pour onto the carb rather than through the breather hose as it should.

Regarding the airbox, the bottom most connection should connect to a drain hose that allows any fuel that's leaked back into the airbox to escape, by routing it down by the bottom of the frame.

The slightly higher airbox connection should have a hose connecting it to a secondary air component that's bolted to the frame up by the cylinder head cover.

The connector at the very top of the airbox should have a breather hose connecting it to the cylinder head cover.

[BikerBoy]

I'll leave any diagnosing to those with more experience, but from what I've gathered from my little experience with carbs it's that you're better off just doing the full carb servicing job from the start rather than changing single components and attempting to fault find, which inevitably leads to taking them on and off many times and often takes longer.

In my marked up image of the carbs, the T connector and hose in the back circled in red is the fuel inlet.

The black T circled in yellow that you're asking about should connect to a carb vent hose. I could be wrong, but not having it connected shouldn't effect the performance, but if fuel overflows through it then it'll just pour onto the carb rather than through the breather hose as it should.

Regarding the airbox, the bottom most connection should connect to a drain hose that allows any fuel that's leaked back into the airbox to escape, by routing it down by the bottom of the frame.

The slightly higher airbox connection should have a hose connecting it to a secondary air component that's bolted to the frame up by the cylinder head cover.

The connector at the very top of the airbox should have a breather hose connecting it to the cylinder head cover.

Great thanks for the detailed info. It sounds like those problem with the carb/airbox arent enough to cause my issues.

I'd like to do the full carb servicing but like you said once you do that then you have to do stuff like sync the carbs (dont have the tools), replace jets and rubber parts etc whereas I just want to get back on the road.

So far Ive been following this video https://www.youtube.com/watch?v=AJh1hxNf7BA its great but one guy says he never cleans the "pilot jet/circuit" is this circuit on the opposite side of the carbs? Id like to keep following this video it makes it really easy. Thanks

[max]

...

Great thanks for the detailed info. It sounds like those problem with the carb/airbox arent enough to cause my issues.

I'd like to do the full carb servicing but like you said once you do that then you have to do stuff like sync the carbs (dont have the tools), replace jets and rubber parts etc whereas I just want to get back on the road.

So far Ive been following this video https://www.youtube.com/watch?v=AJh1hxNf7BA its great but one guy says he never cleans the "pilot jet/circuit" is this circuit on the opposite side of the carbs? Id like to keep following this video it makes it really easy. Thanks

You shouldn't have to re-sync the carbs after a simple cleaning or replacing of those components (assuming it was balanced before).

You can access the jets by removing the float bowls from the carbs. They're the same on each side of the carb.

I've attached an image of the labelled jets (marked up from http://gstwins.com/gsboard/index.php?topic=56601.msg656412#msg656412).

[alpo]

max is correct: that's a vent connection. It is damaged and should be replaced.  You may be able to get by with leaving it alone; me, I'd replace it. If you're somewhat mechanically inclined taking the carbs apart is easy: two screws hold them together.

It's quite possible your pilot jets have clogged from sitting a long time. They can be cleaned fairly easily, but the easiest thing to do is replace them. You will have to remove the float bowls to get to them. Do a search on "gs500 service manual free download" and get a copy of the manual. Or, buy one - your choice. The manual will point out the pilot jets. You will need to remove the float bowls; the jets come out with a straight screwdriver.

[BikerBoy]

I'll leave any diagnosing to those with more experience, but from what I've gathered from my little experience with carbs it's that you're better off just doing the full carb servicing job from the start rather than changing single components and attempting to fault find, which inevitably leads to taking them on and off many times and often takes longer.

In my marked up image of the carbs, the T connector and hose in the back circled in red is the fuel inlet.

The black T circled in yellow that you're asking about should connect to a carb vent hose. I could be wrong, but not having it connected shouldn't effect the performance, but if fuel overflows through it then it'll just pour onto the carb rather than through the breather hose as it should.

Regarding the airbox, the bottom most connection should connect to a drain hose that allows any fuel that's leaked back into the airbox to escape, by routing it down by the bottom of the frame.

The slightly higher airbox connection should have a hose connecting it to a secondary air component that's bolted to the frame up by the cylinder head cover.

The connector at the very top of the airbox should have a breather hose connecting it to the cylinder head cover.

Wow thanks for the great info there. I work better with pictures than words.  I have a feeling it will work too.

[user11235813]

That black rubber bit has a small foam air filter attached. It let air into the top of the carbs to drop the slide down. It's controlled by the two white plastic valves on the top of each carb. When the valves get suction they open up and atmospheric pressure is let into the top of the carbs. Whether the white plastic valves get air or not is controlled by the solenoid which is at the very bottom of on of the carbs attached by a little bracket. If you unplug the solenoid then the valves will never open and no air will get in. Instead of unplugging the solenoid, you can follow the wires up and there's a little plastic connector you can unplug that instead. In fact you can remove the solenoid and all the vacuum tubing too.

In the photo below the air filter is still attached but it could just as well not be there because the solenoid has been removed. The two white plastic valve have been connected with a bit of tubing just to close them off, but again it wouldn't matter because they cannot receive engine vacuum to open anyway but I thought it's better to shut them off. Have a bit of rubber glove blocking the air vent anyway, you can see it poking out!

Or you can leave all the vacuum tubing on, and just unplug the solenoid to see if it makes any difference, (it doesn't)

[mr72]

since you are going to be replacing the pilot jets (probably), go ahead and get 20s. The reason you can't really clean them is because the stock pilot jet is only 0.175mm ... that's tiny! It's very easily clogged and difficult to get something in it to clean. The taper is also sort of important so getting it right is worth it.

[BikerBoy]

That black rubber bit has a small foam air filter attached. It let air into the top of the carbs to drop the slide down. It's controlled by the two white plastic valves on the top of each carb. When the valves get suction they open up and atmospheric pressure is let into the top of the carbs. Whether the white plastic valves get air or not is controlled by the solenoid which is at the very bottom of on of the carbs attached by a little bracket. If you unplug the solenoid then the valves will never open and no air will get in. Instead of unplugging the solenoid, you can follow the wires up and there's a little plastic connector you can unplug that instead. In fact you can remove the solenoid and all the vacuum tubing too.

In the photo below the air filter is still attached but it could just as well not be there because the solenoid has been removed. The two white plastic valve have been connected with a bit of tubing just to close them off, but again it wouldn't matter because they cannot receive engine vacuum to open anyway but I thought it's better to shut them off. Have a bit of rubber glove blocking the air vent anyway, you can see it poking out!

Or you can leave all the vacuum tubing on, and just unplug the solenoid to see if it makes any difference, (it doesn't)

Thats interesting. So theres no need to have the vacuuum hosing at all? What about the electrical components that are left unplugged, I have a 2008 which has 2 electrical sockets in the carbs. What do they do?

[user11235813]

@BB, Thats interesting. So theres no need to have the vacuuum hosing at all?

Correct. Just one hose coming from the right side carb going to the vacuum operated petcock. Because it uses a different size hose I left the T piece on and blocked it off with a bit of old hose bent over and wrapped with copper wire, as you can see on the photo.

What about the electrical components that are left unplugged, I have a 2008 which has 2 electrical sockets in the carbs. What do they do?

The one of the bottom that connects into the vacuum lines is a solenoid that lets vacuum route to the white plastic valves on the top of the carbs which allow atmospheric air in via that rubber T piece you referred to in your first post. That causes the slides to drop down.

If you want to test this yourself, you can leave all the vacuum hoses and solenoid in place and unplug the solenoid, further upstream. Theres some electrical wires coming off the solenoid and you can follow them up till you come to a little white plastic connector, you can unplug that and then there's no power going to the solenoid, so it's not letting any vacuum go to the valves and you can then confirm that it makes no noticeable difference. However you can be certain it's not a performance mod. But those hoses are a pita.

The other electrical component on the side of the carbs is the TPS throttle position sensor and you *do* want that to be there.

[BikerBoy]

@BB, Thats interesting. So theres no need to have the vacuuum hosing at all?

Correct. Just one hose coming from the right side carb going to the vacuum operated petcock. Because it uses a different size hose I left the T piece on and blocked it off with a bit of old hose bent over and wrapped with copper wire, as you can see on the photo.

What about the electrical components that are left unplugged, I have a 2008 which has 2 electrical sockets in the carbs. What do they do?

The one of the bottom that connects into the vacuum lines is a solenoid that lets vacuum route to the white plastic valves on the top of the carbs which allow atmospheric air in via that rubber T piece you referred to in your first post. That causes the slides to drop down.

If you want to test this yourself, you can leave all the vacuum hoses and solenoid in place and unplug the solenoid, further upstream. Theres some electrical wires coming off the solenoid and you can follow them up till you come to a little white plastic connector, you can unplug that and then there's no power going to the solenoid, so it's not letting any vacuum go to the valves and you can then confirm that it makes no noticeable difference. However you can be certain it's not a performance mod. But those hoses are a pita.

The other electrical component on the side of the carbs is the TPS throttle position sensor and you *do* want that to be there.

Cool, I think I may copy your design then. I think the vacuum circuit might be the reason my bike wont start now. what year is your bike?

So I cleaned my bikes carbs recently and sure enough, both the pilot jets were completely clogged. Needed a heavy dosing of compressed air, carb cleaner, and guitar string to get them clean again. However putting the vacuum circuit back together wasnt as natural as taking it apart, so I'm sure I screwed it up somewhere. The thing is Im not sure if the vacuum circuit is why my bike wont start but I think it is.

I will do some troubleshooting by:
1. emptying gas tank with old gas and re-fueling it to the top with new fuel,
2. checking fuel lines, making sure the PRI goes to the carb, ON goes to the gas tank (shorter tube), RES goes to gas tank (longer tube), and ensuring fuel lines aren't pinched under the airbox
3. cut up the vacuum circuit the way you did and make sure there are no leaks in the tubing to the petcock

So after putting it all together (I think) I turned it on PRI and tried to start it every 5-10 minutes until the battery died. The headlights would turn on and it would try to start but never combusted. I tried switching it to ON and RES in case I confused fuel lines but it still didnt start. Then I tried draining the nipples on the carbs to see if fuel is getting to them, and weirdly only the left carb had fuel in it! Im not sure if this is because it was on its kickstand so all the fuel went to the left one after I started it but I was starting it with the kickstand up and in Neutral.

Anyway my amateur thinking is that because the vacuum circuit was messed up there wasnt enough fuel getting to the carbs for it to start, or perhaps the battery wasnt at enough charge to ignite. I recharged the battery and its on a tender now. Also going to check the breather hoses are in the right spots.

Added bonus: picture of my non-working carbs in my bike after cleaning. https://imgur.com/a/jB5zdXp

[user11235813]

Mine is a 2010, but I do not have that extra emissions control stuff that is mounted to the left side of the crossbar under the tank. Carb cleaner will damage any rubber bits on the carb like the diaphragm and  o rings, so you do need to be aware of that.

[mr72]

For a non-starting GS, there are some nuances worth clarifying.

Does it ever begin to catch or fire AT ALL? Like, can it catch on for a couple of cycles then dies?
  -- if it NEVER catches AT ALL then one of three things is (likely) happening:
       a. it never gets any fuel AT ALL ... fuel hoses are connected wrong petcock never opens even on PRI, pilot passage clogged in the carb
       b. it is not getting any spark ... likely electrical, could you have inadvertently disconnected a wire, particularly a ground wire?
       c. it's flooded and the plugs are fuel fouled ... Are either of the plugs wet with fuel?

Vacuum is not your problem if the bike WON'T START.

The only part of the starting mechanics affected by vacuum is the petcock. You can completely bypass that by putting it on PRI.

If you are confident that it is getting a spark and it won't start then it almost certainly guarantees the fuel passages that feed the pilot jets are clogged. The fact that you report your pilot jets were clogged is a good indicator that the passages are likely also clogged. Why didn't you replace the pilot jets? While you had it apart would have been a good time to just replace them with 20s, you are going to eventually want to do that anyway.

That guitar string you used to clean the pilot jets? You can use it to run through the passage that feeds the pilot jet. Better yet to tear the carbs down (take out ALL rubber parts, including the pilot needles and o-rings) and then soak the carb bodies submerged in carb cleaner for a day or so to break down the gunk that might be stuck in there THEN run your wire through it. And when you put it all back together put fresh o-rings in everywhere, including the pilot needle o-rings.

Also run that guitar string through the pilot air passage that runs from the throat of the carb, it's one of those little holes near the rim of the carb throat. I can't point you exactly because I'm not so familiar with the 3-ckt carbs and they're slightly different.

Sounds like your float levels are also not right since each carb drained a different amount of fuel, so while you have it apart, worth it to double-check and set the float level. Also I'd replace the float needles while it's apart. Actually I'd just do the entire procedure outlined on my blog with the addition of soaking/clearing that pilot passage which is most likely clogged.

Once you get the bike to start you may find other issues that are caused by vacuum leaks but vacuum issues won't prevent the bike from starting. They will cause it to run lean or not get off of the pilot jet etc. but vacuum is not really involved at starting. The starter turns over at like 300 rpm or less, there's not enough vacuum developed to draw in any significant amount of air and the only thing that might really be affected is the petcock, which you can bypass.

[BikerBoy]

For a non-starting GS, there are some nuances worth clarifying.

Does it ever begin to catch or fire AT ALL? Like, can it catch on for a couple of cycles then dies?
  -- if it NEVER catches AT ALL then one of three things is (likely) happening:
       a. it never gets any fuel AT ALL ... fuel hoses are connected wrong petcock never opens even on PRI, pilot passage clogged in the carb
       b. it is not getting any spark ... likely electrical, could you have inadvertently disconnected a wire, particularly a ground wire?
       c. it's flooded and the plugs are fuel fouled ... Are either of the plugs wet with fuel?

Vacuum is not your problem if the bike WON'T START.

The only part of the starting mechanics affected by vacuum is the petcock. You can completely bypass that by putting it on PRI.

If you are confident that it is getting a spark and it won't start then it almost certainly guarantees the fuel passages that feed the pilot jets are clogged. The fact that you report your pilot jets were clogged is a good indicator that the passages are likely also clogged. Why didn't you replace the pilot jets? While you had it apart would have been a good time to just replace them with 20s, you are going to eventually want to do that anyway.

That guitar string you used to clean the pilot jets? You can use it to run through the passage that feeds the pilot jet. Better yet to tear the carbs down (take out ALL rubber parts, including the pilot needles and o-rings) and then soak the carb bodies submerged in carb cleaner for a day or so to break down the gunk that might be stuck in there THEN run your wire through it. And when you put it all back together put fresh o-rings in everywhere, including the pilot needle o-rings.

Also run that guitar string through the pilot air passage that runs from the throat of the carb, it's one of those little holes near the rim of the carb throat. I can't point you exactly because I'm not so familiar with the 3-ckt carbs and they're slightly different.

Sounds like your float levels are also not right since each carb drained a different amount of fuel, so while you have it apart, worth it to double-check and set the float level. Also I'd replace the float needles while it's apart. Actually I'd just do the entire procedure outlined on my blog with the addition of soaking/clearing that pilot passage which is most likely clogged.

Once you get the bike to start you may find other issues that are caused by vacuum leaks but vacuum issues won't prevent the bike from starting. They will cause it to run lean or not get off of the pilot jet etc. but vacuum is not really involved at starting. The starter turns over at like 300 rpm or less, there's not enough vacuum developed to draw in any significant amount of air and the only thing that might really be affected is the petcock, which you can bypass.

Nope the bike doesnt catch or fire, not even once since I cleaned the carbs, whereas before I cleaned it, it started idling right away but bogged down and died once I gave it throttle or after I idled it for 30 seconds.

1. Id rather not change the jets now because I've read that you should change the air filter too since its not stock anymore. But its something I'd like to do maybe over the winter, now I just want to get it to run.

2. Where are the spark plugs located?

When I can look at my bike this weekend I will drain the carbs, put the bike up evenly on its centerstand, turn it on PRI, and drain them again, checking if the left carb is truly getting more gas than the right - if gas can shift between the carbs then the left probably had more because I checked when it was on its sidestand. Also I will check the battery voltage with a multimeter for good measure..

My hunch is the vacuum line on the petcock is open somewhere since I didnt know what I was doing when reassembling, so gas may not have been there sufficiently when I set it to on. And I was trying to start the bike in the ON, PRI, and RES settings since I wasnt 100% sure where they were supposed to go (now I know where they go, and that youre supposed to only try to start the bike in PRI after carb cleaning) Or the battery was low already and when gas got there the charge wasnt enough for it to start the bike.

I was gonna have to take the carbs off again since my vacuum was all messed up so Ill clean the passageways this weekend when I do that too. Thank you.

[user11235813]

Where are the spark plugs located?

Please tell me you're joking. If you're not joking maybe you should also check the spade connectors to the ignition coil which are those two electrical cylindrical object on either side and to the front of the crossbar on the frame under the tank. Be very careful not to over tighten the spark plug! Same with the oil filter cover nuts.

[mr72]

1. Id rather not change the jets now because I've read that you should change the air filter too since its not stock anymore.

Well, that's not even close to correct.

2. Where are the spark plugs located?
...
My hunch is the vacuum line on the petcock is open somewhere since I didnt know what I was doing when reassembling, so gas may not have been there sufficiently when I set it to on. And I was trying to start the bike in the ON, PRI, and RES settings since I wasnt 100% sure where they were supposed to go

If you tried it on PRI and it didn't start then this is not the problem. If there was ANY fuel in the carbs, this is not the problem. If you don't get the vacuum line connected and then you do get it to start, it will likely die after a few minutes if it's not connected because it will drain the carb bowls of fuel, but as long as it has been put on PRI long enough to prime the carbs, it'll start and run just fine with the petcock off.

I was gonna have to take the carbs off again since my vacuum was all messed up so Ill clean the passageways this weekend when I do that too. Thank you.

Don't bother until you have new #20 pilot jets. Work on making sure it has a spark. If it doesn't catch at all even with fuel in the carbs then it is almost guaranteed to be ignition.

That said, if you really didn't know what you were doing pulling the carbs off then there may be a dozen other things wrong. It really does take at least a little bit of preparation and education.

[sledge]

The best advice anyone can give you Bikerboy is to give up now and seek professional help.

Don't get me wrong and appologies for being blunt but if you don't know where the plugs are you have no chance of successfully removing, cleaning and reinstalling a set of carbs  or diagnosing any related issues

[mr72]

for once I might agree with Sledge. If you don't know where the spark plugs are then you need to get some help. Gotta start somewhere.