2004 Suzuki GS500F - Diagnosis Help

[xanderhaymore1000]

Hello GSTwins forum! I'm brand new to the riding community and recently bought a 2004 Suzuki GS500F as a starter bike. She looks great and the body is in mint condition, she just doesn't run properly. Like I said I'm relatively new to this sort of thing so I'm not super super handy at working on / understanding the function of a motorcycles parts (especially a carbed one like mine), so I was looking for some help diagnosing problems and things I could look into fixing.
The only thing I've looked into doing and accomplished was taking the carbs out and cleaning them with carb cleaner, making sure the pilot jets, etc weren't clogged, and so on. That seemed to help the bike a bit but it still is not rideable on the streets. Here are the symptoms:

Symptoms: First: starting - the bike has trouble starting. Before I cleaned out the carbs, I had to find a "sweet spot" on the choke for it to start, if i got lucky enough for it to start. Now the bike starts much better with it fully choked (so that issue has been dealt with after carb clean) but now the bike dies sometimes and even with the choke fully on only goes to about 2k RPM. Meanless to say the bike won't idle or be driven without the choke on, once I take the choke off the rpms drop really low, chugs, and the bike dies unless I rev it.

Second: The bike backfires a ton. If I'm trying to help warm it up a bit or just flat out keep it alive when I have the choke only half on, the bike backfires like crazy, sometimes like a machine-gun. Keep in mind this isn't me redlining or downshifting or anything, it's just idle and I'm revving to around 4k. (The bike has a modified exhaust that is very short, so Idk if that could have something to do with it.)

Third: This goes along with the previous two, but the bike, when I ride it (which I've done just a couple times for a minute to test to see what was wrong with it) has little to no power in first or second gear and I haven't gone fast enough for 3rd-6th.

Fourth: I was watching a video on how to clean carb jets and during the process I noticed that my bike did not have one of the hoses the video said it would. One of the steps was to "unhook tank vent hose and remove fuel tank." There was no vent hose on the tank. I see the small opening for where I assume one would go, but it doesn't look like the bike had/has one, is this a problem? could it be causing some issues?
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What I've done so far / observed: I've disassembled the carb and airbox. I cleaned the carb jets (the needles) (my terminology isn't up to par, as I'm new to this haha), which like I said helped a bit - some of the jets were definitely clogged. I inspected the airbox and noticed the air filter is really dirty, so I'm going to get a new one, but Idk if a dirty airbox fits in with any of the symptoms the bike is going through. I'm just wondering what else I can do to try to get her riding again, I'm itching to get on the road. I've had my license but no working bike and it's killling meh.

A little background on the bike: Figured this might help - I bought the bike from 2 guys that I trust, they were upfront and said the bike runs but not well and needs a little work before it'll be perfect again. The bike had been sitting for about a month (according to them). Like I mentioned, the bike has a shorter exhaust pipe that's loud as crap. The neutral light doesn't work.
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Basically I just need help with coming up with ideas for me to look into fixing, replacing, etc because I'm new to the biking maintenance realm. Thank you guys so much, I hope I can start my riding journey soon!

[mr72]

You need to go see the FAQ and follow whatever maintenance instructions are there for "carb cleaning".

The most important thing is that you do NOT spray carb cleaner on the carburetor at all (or in the throat, any orifices, etc.) until you disassemble it and remove all rubber parts especially and including the diaphragm under the plastic top of the carb.

I should write an FAQ article just on how to begin rejuvenating these carbs because I write these instructions at least once a week.

Your symptoms sound to me like a combination of clogged jets (all of them, including the "choke"), low floats, maybe a bad (sticking closed) float needle, potentially bad rubber diaphragms causing the slides to not move up (and down), and generally lean idle setting due to undersized pilot jet. Probably a half dozen leaking o-rings and a vacuum leak or three. Standard stuff.

Anyway, start with the FAQ carb cleaning instructions and also set float height, change jets, etc. Just live with the FAQ maintenance section for a while.

[ShowBizWolf]

I should write an FAQ article just on how to begin rejuvenating these carbs because I write these instructions at least once a week.

If you have time to do that, it would be awesome IMO. You really do help a lot of people with carbs. I've done some updates to the wiki recently and it really bugs me when information is confusing and picture links are broken. I wish I could fix it all lol !!

[xanderhaymore1000]

You need to go see the FAQ and follow whatever maintenance instructions are there for "carb cleaning".

The most important thing is that you do NOT spray carb cleaner on the carburetor at all (or in the throat, any orifices, etc.) until you disassemble it and remove all rubber parts especially and including the diaphragm under the plastic top of the carb.

I should write an FAQ article just on how to begin rejuvenating these carbs because I write these instructions at least once a week.

Your symptoms sound to me like a combination of clogged jets (all of them, including the "choke"), low floats, maybe a bad (sticking closed) float needle, potentially bad rubber diaphragms causing the slides to not move up (and down), and generally lean idle setting due to undersized pilot jet. Probably a half dozen leaking o-rings and a vacuum leak or three. Standard stuff.

Anyway, start with the FAQ carb cleaning instructions and also set float height, change jets, etc. Just live with the FAQ maintenance section for a while.

Thanks so much for your reply! Could you link me to the FAQ section you're talking about that has to do with carb cleaning? I've been looking for a while and can't find the section you're referring to.

[ShowBizWolf]

This is the FAQ section of the forum http://gstwins.com/gsboard/index.php?board=7.0 but I'm not sure which one would have the carb cleaning details in it.

I gave the 3 pages of topics a read through twice but didn't see anything... although it could be that good ol' "Front-Shelf Blindness" thing kickin' in lol!

[xanderhaymore1000]

This is the FAQ section of the forum http://gstwins.com/gsboard/index.php?board=7.0 but I'm not sure which one would have the carb cleaning details in it.

I gave the 3 pages of topics a read through twice but didn't see anything... although it could be that good ol' "Front-Shelf Blindness" thing kickin' in lol!

Thanks for your reply. Yeah exactly, I too read over the topic pages and can't find anything related to carb cleaning.. or even maintenance for that matter.

[ShowBizWolf]

I thought of this thread too: http://gstwins.com/gsboard/index.php?topic=56601.0 but it has a LOT of broken picture links in it (at least for me)

I'm gonna take a stab in the dark and suggest searching on YouTube for something like "gs500 carb cleaning" or something similar... maybe that will turn up something helpful! Ooo I just found this one here: https://www.youtube.com/watch?v=AJh1hxNf7BA&feature=youtu.be

[Endopotential]

As you seem to be new to bikes, and especially to taking apart carbs...  Just double check all the parts that you took out and put back in.  There's a lot of rubber O-rings, springs, and tiny washers that can be forgotten.  Any tiny vacuum leak can screw up the bike.

I've done mine three times now, and still catch myself.  I think 2004 had 3 circuits for the jets.  The main and mid jets look the same - make sure you didn't put them in the wrong spots.

Also check that the plate at the front of the carbs that controls the choke slides laterally easily.  Mine was sticky, so the choke lever wasn't doing what it was supposed to.

Good luck!

[mr72]

I should write an FAQ article just on how to begin rejuvenating these carbs because I write these instructions at least once a week.

If you have time to do that, it would be awesome IMO. You really do help a lot of people with carbs. I've done some updates to the wiki recently and it really bugs me when information is confusing and picture links are broken. I wish I could fix it all lol !!

Well I wrote something up and tried to post it but the wiki refuses to save edits.

Fortunately I saved it in another document. I'll try to post again later. Meantime if someone wants to figure out/fix the wiki then let me know when I can post, go for it

[ShowBizWolf]

That is strange! Every time I've edited the wiki it saved for me thankfully.

When you click on the Edit tab at the top and then type in the password, does it bring up the editing screen with buttons at the bottom? There should be Save, Save and Edit, Preview and Cancel.

Just wondering if we're looking at the same thing or not cuz there are some areas of the wiki that act kinda funny sometimes lol!!

[mr72]

When you click on the Edit tab at the top and then type in the password, does it bring up the editing screen with buttons at the bottom? There should be Save, Save and Edit, Preview and Cancel.

Yeah it just returns a 500 after a long time "Waiting for wiki.gstwins.com" when I click "Save" or "Save and Edit" etc.

Also "Preview" deletes everything and returns blank. Makes me wonder whether the post is too long or has some other data in it that's not allowed.

--

Internal Server Error

The server encountered an internal error or misconfiguration and was unable to complete your request.

Please contact the server administrator, webmaster@wiki.gstwins.com and inform them of the time the error occurred, and anything you might have done that may have caused the error.

More information about this error may be available in the server error log.

Additionally, a 500 Internal Server Error error was encountered while trying to use an ErrorDocument to handle the request.

[ShowBizWolf]

Poops 

Well in that case... maybe send John or Janx or another moderator a PM and ask if it can be made into a sticky in the FAQ section... I bet that'd be good!

[mr72]

I think the problem is it doesn't like me pasting it in. I can't manage to get anything to work if I copy/paste. But it works fine if I type things directly into the editor. Also it looks like this wiki was made in about 1997.

Just to make everything easier (and to make it work) I just posted it to my blog. I linked it from the wiki.

Blog: https://joshkarnes.blogspot.com/2017/09/fixing-common-gs500-carburetor-issues.html

Wiki: http://wiki.gstwins.com/index.php?n=Maintenance.RoutineMaintenance -- "Fixing Common Carb Issues"

[rocketgirl]

Just to make everything easier (and to make it work) I just posted it to my blog. I linked it from the wiki.

Blog: https://joshkarnes.blogspot.com/2017/09/fixing-common-gs500-carburetor-issues.html

Very nice write up.   Thanks for doing this.

[mr72]

BTW I just updated the post. Put in a picture

Also fixed a bunch of formatting and did a little bit of rewriting.

Should be a pretty good guide now.

https://joshkarnes.blogspot.com/2017/09/fixing-common-gs500-carburetor-issues.html

[xanderhaymore1000]

Hey, so during my taking off of the diaphragms and whatnot I noticed that there's a piece on one diaphragm that isn't on the other one. Could this be causing the issue? Or add to causing the issues?
Pictures attached. The piece I'm referring to is that black thing. The right side has it and the left side did not have it.

Link to photo: https://ibb.co/c1WGGG

[xanderhaymore1000]

I think the problem is it doesn't like me pasting it in. I can't manage to get anything to work if I copy/paste. But it works fine if I type things directly into the editor. Also it looks like this wiki was made in about 1997.

Just to make everything easier (and to make it work) I just posted it to my blog. I linked it from the wiki.

Blog: https://joshkarnes.blogspot.com/2017/09/fixing-common-gs500-carburetor-issues.html

Wiki: http://wiki.gstwins.com/index.php?n=Maintenance.RoutineMaintenance -- "Fixing Common Carb Issues"

I've been following your right up to the best of my ability and so far I've noticed a lot of what you mention should be there isn't there. Such as the "Remove the plastic tops (with the "little o-ring" on each)" step. I don't know what you mean by plastic top but I assumed you were referring to the cover for the diaphragms, there is no o-ring on them.
Another example is when you say to unscrew the pilot adjustment screw - you say there should be a spring, washer, and o-ring, whereas mine came out as the picture below shows (linked) and only had a spring and the pilot screw itself. Am I doing something stupid? I checked in the holes of the pilot screw and there's nothing in there from the o-ring falling out or anything like that.

Also, one quick stupid question: When applying carb cleaner do I just spray the foam and let it sit ten minutes then kinda blow it off a bit or do I wash it with water or what?

Picture: https://ibb.co/ccgiwG

[mr72]

Such as the "Remove the plastic tops (with the "little o-ring" on each)" step. I don't know what you mean by plastic top but I assumed you were referring to the cover for the diaphragms, there is no o-ring on them.

Sorry, I'll update my blog. There is an o-ring on the pre-2000 carbs that frequently gets lost. I am not sure there is one for your carbs.

Another example is when you say to unscrew the pilot adjustment screw - you say there should be a spring, washer, and o-ring, whereas mine came out as the picture below shows (linked) and only had a spring and the pilot screw itself. Am I doing something stupid? I checked in the holes of the pilot screw and there's nothing in there from the o-ring falling out or anything like that.

If you look on the diagram on this site:
http://www.bikebandit.com/oem-parts/2004-suzuki-gs500f-carburetor-model-k4/o/m6061sch503304

You will see a parts breakdown of your carbs. #17 is the o-ring, #18 is the washer.

Either a) someone else previously took your carbs apart and lost these parts, or b) the washer is stuck to the o-ring and still stuck up in the hole.

This why I said this:
"If the pilot needle o-ring doesn't come out, then you have to pick it out using a pick-like tool or a piece of bent wire; they tend to get jammed up in the hole. If an o-ring doesn't come out, it is not likely because it wasn't there in the first place. If there was no o-ring at all on the pilot needle it would leak a lot of fuel from the idle mixture adjuster. "

The parts are almost guaranteed to be up in there. If you attempted to put it together without the o-ring and washer, like if they really didn't exist in there, then it would constantly drip fuel from the pilot adjuster, at least until the float bowls were empty (bike sitting). When running it would have ridiculous erratic idle, probably fail to start, sometimes start and then just die, idle be all over the place, etc. I know this from first-hand experience If the bike starts and runs and idles even remotely consistently and fuel doesn't drip constantly from the mixture adjusters, then there is an o-ring and washer in there.

What can happen is either they are stuck together and still in there, or the washer fell out and disappeared into oblivion in your garage and the o-ring is still stuck in there.

My spare set of carbs (the originals from my bike) are currently sitting one with no o-ring and no washer and the other with no o-ring, because #1 I lost the washer for one of them and then when I decided to cut bait on those carbs I didn't bother putting in new o-rings.

It is a chore to pick out the old o-rings if they are stuck in there. I used a piece of 22AWG bare wire with about the last ~1mm bent into an "L" shape to pick them out on all four of the carbs I have here. The o-rings didn't just come out on any of them. OTOH once I put in new ones, the new ones tend to come out easier with the needle since they also sort of stick to the needle. And also since they are pliable, they are much easier to pick out, usually you just have to shove the pick tool up in there one time and when you remove it, the o-ring comes with it.

Also, one quick stupid question: When applying carb cleaner do I just spray the foam and let it sit ten minutes then kinda blow it off a bit or do I wash it with water or what?

I've never seen carb cleaner that's a "foam". But once you have all rubber and plastic parts off of the carb (including the parts that have o-rings between them like the slides and the brass float needle seats) then you can do whatever you want. I use B12 Chemtool and either spray it through the carbs using the little red straw on an aerosol can or pour some B12 into an open container of some sort and submerge the carb body in it, particularly for very small carbs like my weed eater (which by the way makes my GS500 carbs seem like child's play).

Good luck!

[xanderhaymore1000]

Hey, so during my taking off of the diaphragms and whatnot I noticed that there's a piece on one diaphragm that isn't on the other one. Could this be causing the issue? Or add to causing the issues?
Pictures attached. The piece I'm referring to is that black thing. The right side has it and the left side did not have it.

Link to photo: https://ibb.co/c1WGGG

Thanks so much mr72! You're helping me out so much haha. Last question (probably). Any idea about the diaphgragm part I have quoted above?