Quote from: Endopotential on September 23, 2016, 12:15:29 AM
Hey Josh, just want to keep cheering you on!

Thanks!

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Just finished my own GS project this summer, and took apart the carbs at least twice in the process.

Well I've had each pair of carbs apart at least twice already. One of these days it'll be the last time I have to take the apart to get the bike to run!

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- these bikes seem plagued by vacuum leaks. ...

No kidding. I think I have chased them down on this bike, who knows about the "new" carbs. Mine ('92) doesn't have PAIR. My history of leaving the petcock on prime seems to indicate I should try and stick with the vacuum petcock for the time being. But I wouldn't mind if it had an "OFF" manual setting.

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- make sure the slides bounce up and down easily ...

They do with the carbs off the bike. Haven't looked with it running.

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- the bracket /slide plate that opens and closes the choke on the carbs can bind.  I had to put in delrin washers on mine to get it aligned properly, so that it would slide easily back and forth.

I wondered about that. Seems like a rather imprecise assembly. I wonder if that was not one of my problems with the original carbs.

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- run the bike with the gas tank and air filter off (run a temporary fuel system with a funnel or turkey baster, but stay safe). 

Yeah next time I have the tank off, I'll have to give this a shot. I really am hoping to not have to deal with this for a while.

I mean, truth is, I just want this bike to run so I can go ride it some and make a meaningful decision on whether I keep it for a long time and do the mechanical and cosmetic work it would need to be a long-term addition to my home, or whether it's not the bike for me and I flip it and buy something else (with fuel injection!).

Update:

Friday I started it up and rode down my steep driveway and it died on the street. It was surging when aimed downhill which was strange to say the least. It wouldn't start again, so I left it sitting overnight on the street. It's too heavy to push back up my driveway.

Saturday morning I went out and pulled the carbs again. I have got this down to a science, let me tell you. There was liquid gas in the intake boots and one plug was wet with gas even after sitting overnight. I re-checked the float height and it looks like for whatever reason I really had myself fooled before. The floats were too high so I adjusted them and for good measure I put the float needles from the original carbs into the "new" ones. They all looked to be in just fine shape but the "new" carb had one float needle sticking and I didn't want to risk it.

Now, putting it back together, I discovered something. Anyone else get annoyed putting the stock airbox on? Well I think I have that licked. First of all, I used some "General Purpose Cement" from Harbor Freight to glue the airbox boots in place, since they kept popping out of their hole when I wrestled with it before. Any decent rubber-based cement will work, but this sub-$1 stuff works perfectly. Now when you go to put the airbox in, first get the fuel petcock and hoses completely out of the way. Then put the REAR of the airbox in first, with it tilted like 60 degrees. It will slide right in to its spot. Then with the air filter out, put a hand inside the airbox and manipulate the boots over the carb throats from the inside. Just like that, I had the airbox in there in like 30 seconds this way. The real key is gluing in the boots, and then knowing to put the rear of the airbox in first with it tilted.

Once I had it all together I noticed visible "junk" in the reserve fuel hose. I pulled it loose from the petcock and drained it. Didn't want that "junk" in the carbs! Then I tried to start it and it wouldn't fire. Figured out eventually that the tank petcock was turned just a little bit PAST vertical, which results in restricted or no fuel flow. You know it will turn like 110 degrees, but you need it at 90 degrees for it to flow. Lovely. Once I got THAT sorted, I started it up and it ran just like it was supposed to for long enough for me to notice it dripping fuel from one of the fuel hoses. Turned it off and then tightened the snot out of the tank hose clamps. Now no leaks. Petcock in the right place. Everything together. Started it up and voila! It fired right up, revved itself to 5K rpms, and it works pretty well. Well enough for me to ride it up into my garage.

This morning I decided to go out and fiddle with the idle mixture and idle speed on the "new" carbs. I wound up with 3.5 turns out and I still think it may be a little lean. I rode it about 5 miles until it started raining, and set the idle to about 1500 rpm with it hot.

I still think it needs idle tuning, but I also think it CAN be made to run right now.

It has a little stumble coming off idle and I think that's because it's lean. It has a little hanging idle, again likely lean. But that I can fix.

Other good news is that it seems to be capable of starting while the engine is hot. Getting closer to a usable motorcycle here. I thought the day may never come.

If we didn't have thunderstorms in the forecast all afternoon and evening I'd be out riding it now.

Next time you have the carbs off, pull the jets and with compressed air, blow air in every frigging hole under the bowls 

Topic: Idle troubles: Maybe pull the idle mixture screws too and blow some compressed air in there, also any small holes in the bores/carb body's, don't blow any air in the large ports on top, those ports supply vacuum for the slides.....they are not potentially clogged like the small holes in the body's might be.

That's great to hear!


Sent from my iPhone using Tapatalk

Quote from: Suzuki Stevo on September 25, 2016, 04:48:24 PM
Next time you have the carbs off, pull the jets and with compressed air, blow air in every frigging hole under the bowls 

Topic: Idle troubles: Maybe pull the idle mixture screws too and blow some compressed air in there, also any small holes in the bores/carb body's, don't blow any air in the large ports on top, those ports supply vacuum for the slides.....they are not potentially clogged like the small holes in the body's might be.

Funny. I actually thought of doing exactly that when they were off, but my air compressor was also broken. So I used a .013" guitar string to run through every orifice. Then I got the valve rebuild kit for my air compressor in the mail later Saturday and repaired it. So next time, I'm golden!

Here's hoping there's not a next time for me to have the carbs off. At least not in 2016! Chances are slim, I know.

Question: what affects idle speed more, the mixture or the idle speed screw? I am still having the issue I had with the previous carbs where it will idle at like 2.5-3K rpm and then if I turn the idle screw just like 1/16 of  turn, it goes down to like 900. Does this indicate an idle mixture problem or something else?

It's funny it is doing basically the same thing with the second set of carbs which makes me also think I need to get serious about checking the valve clearances.

Alright. My dislike for this thing is increasing.

Yesterday I had a few minutes and given the gorgeous weather we are supposed to have here for the next week I figured I need to get the bike working so I can go ride it with my dad this weekend. BTW, lest any of you think by saying "my dad" all the time I'm some kid, well I'm not. My dad just turned 65 and I'm 43. Riding motorcycles in a leisurely fashion is something he wants to do to enjoy his pre-retirement spare time, and it's pretty much the whole reason I bought a motorcycle.

So I went out and rode around the neighborhood a bit just to a) get the bike warmed up enough to set the idle and b) build my confidence that the ol' GS is not going to strand me at a stop sign.

Good news is that it started right up and ran like it is supposed to when it was stone cold. I went ahead and started riding with part choke on and then turned off the choke completely after about 5 minutes. Bike was a little stumbly coming off low/idle revs at initial throttle opening which I now realize may very well be caused by a vacuum leak (did I mention I hate these carbs?). But overall, it ran just pretty great. After riding for about 10 minutes I decided to try setting the idle. I set it lower than it was (it was hovering around 3K) down to under 2K but I didn't want to go too far and have it stall at a stop sign. Eventually after riding for about 20-30 minutes I returned home and tinkered with the mixture a tad trying to get it to idle. I was still not able to get it to idle correctly.

I can set it to idle at about 2K rpms but if I try to drop it any more, it idles below 1K and stalls if I don't keep bumping the throttle. And it's very sluggish coming off "idle" when it is trying to idle at whatever 500 rpm that it is trying to do.

So, I went ahead and pulled it into the garage where it predictably stalled (it's never made it into my garage without dying). The frikin' thing WOULD NOT START again. So it won't start while hot. I tried with some choke, all choke, no choke, it just won't start.

And this is exactly where I started. Only now I have different carburetors and I have spent probably 20 hours working on this blasted thing. It will idle either at 2K+ or it will die, and it will not start when hot.

Someone posted a 2007 GS500F with under 3K miles on it on the local CL for $1K and I am incredibly tempted to just go buy it, drop the money into the F-E conversion and sell old red. Give up. I hate to consider that since even though the 2007 is much newer it is far more complicated to work on and I have no love for the fairings or appearance. But I just need something that will run reliably and I am beginning to think this old klunker won't ever do that.

Anyway, back on to the issues. As I was getting off of the bike, contemplating what might have gone wrong, I noticed an alarming sight. One of the tiny little washers that goes on the idle mixture needle was laying on my workbench. That means it wasn't in the carb! Maybe that explains why one of the carbs did not seem to be responding to mixture changes. And that might be the whole problem. Can any of you confirm that this washer missing may cause poor idle AND not starting while hot?

Later last night I pulled the needle screw and for sure, the unresponsive carb had no washer. I managed to plug the o-ring out with a toothpick and it was also rather flat but seemed kind of OK. I had a spare so I replaced it. For good measure I pulled the needle from the other carb and it had the washer, but I was not able to get any o-ring to come out of the hole (I didn't pull the carbs). Maybe there's one stuck in there, who knows. Maybe it got lost while I had the carbs torn down, like the washer for the other carb. So I put the mildly flattened o-ring from the other carb in there just in case, figuring two flattened o-rings is probably not a disaster but I'll order new ones for both sides anyway. I re-adjusted to 3 turns out AGAIN and I'll try my tuning exercise AGAIN today after work.

I seriously need solid advice on why the bike won't start when hot. And this is not some kind of electrical problem. The starter turns just fine. It occasionally tries to fire. It kind of behaves like it's flooded to some degree, but I didn't pull the plugs to see if they are fouled. I figure it could be one of the following:

• Missing o-rings and washers on idle mixture needles caused erratic fuel delivery and it's super rich at idle, flooding. Why then would it start when cold? Are the plugs just drying?
• Missing o-rings and washers on idle mixture needles caused vacuum leak which screwed up my idle stability as well as prevents starting, but why only when hot? Maybe because the choke fixes this when cold, but when it's hot the choke makes it too rich?
• Some other undiagnosed problem is causing everything wrong... maybe it won't idle under 2K rpm because the igniter is not working correctly on 12V battery voltage and only has enough juice when running on the alternator's voltage but it only acts like this when it is hot. Maybe tight exhaust valves are causing the poor idle and no-start because of no compression at low rpms but the clearance is bigger when hot and when cold compression is fine. Maybe it's something I am too inexperienced to contemplate.
• Maybe I need a whole different motorcycle.

So should I buy the '07 F and give up on the '92? I only paid $1K for the '92 and it's in better shape now than it was when I bought it. I could definitely get my money back out of it. And $100 in lights and brackets turns the F into an E. Starting to think that's the way better bet.

No point doing anything if the valves are not in spec, If the carbs are stock.

I've owned many of these bikes and when the exhaust valves are really tight, the bike has trouble idling even when fully warm and hard to start. If a little tight, it will run okay when warm.

Quote from: HPP8140 on September 28, 2016, 09:52:45 AM
No point doing anything if the valves are not in spec, If the carbs are stock.

I've owned many of these bikes and when the exhaust valves are really tight, the bike has trouble idling even when fully warm and hard to start. If a little tight, it will run okay when warm.

Yeah but I am having the opposite problem, if I am reading you correctly. Mine starts and runs great when cold and has a 1000-rpm wide hole where it won't run between 1K and 2K rpm where the idle speed jumps when it's hot, and it won't start at all when hot. It's not hard to start when cold, just impossible to start when hot.

IME (with cars ... Miata specifically) a tight valve makes it run rough when cold and one it warms up the alloy head expands more than the valve hardware (valve stem, bucket, shim, cam) and the valve closes fine, runs smooth when hot. I am having opposite issues here.

I'm hopeful that my missing washer and maybe missing o-ring were the root cause of my issue, but I have my doubts. Thinking about it, that o-ring doesn't make much sense because what does it seal on the screw side? A washer? I guess it's possible it seals against the neck of the needle and on the outside against the body of the carb and the washer and spring just keep it in place, but it's weird. I wonder if the bike would run a lot better with a factory-style brass cap pressed back over the idle screws after adjusting ... or even just a rubber plug. What is the leak here anyway? grr.. I need a diagram of fuel and air flow for this carb.

Quote from: mr72 on September 28, 2016, 07:18:00 AM

...

Someone posted a 2007 GS500F with under 3K miles on it on the local CL for $1K and I am incredibly tempted to just go buy it, drop the money into the F-E conversion and sell old red. Give up. I hate to consider that since even though the 2007 is much newer it is far more complicated to work on and I have no love for the fairings or appearance. But I just need something that will run reliably and I am beginning to think this old klunker won't ever do that.

...

So should I buy the '07 F and give up on the '92? I only paid $1K for the '92 and it's in better shape now than it was when I bought it. I could definitely get my money back out of it. And $100 in lights and brackets turns the F into an E. Starting to think that's the way better bet.

The 07 F is not really "far more complicated". Is basically the same bike, with the same engine, except with an oil cooler. And like you said, its extremely easy to just turn it into an E body type. So, if you think you can basically break even on your current bike and buy the more reliable, newer one then that definitely a viable option.

If you do end up buying the F, you can sell the fairings for a couple hundred bucks if they're in good shape.

Quote from: mr72 on September 28, 2016, 10:19:09 AM

Quote from: HPP8140 on September 28, 2016, 09:52:45 AM
No point doing anything if the valves are not in spec, If the carbs are stock.

I've owned many of these bikes and when the exhaust valves are really tight, the bike has trouble idling even when fully warm and hard to start. If a little tight, it will run okay when warm.

Yeah but I am having the opposite problem, if I am reading you correctly. Mine starts and runs great when cold and has a 1000-rpm wide hole where it won't run between 1K and 2K rpm where the idle speed jumps when it's hot, and it won't start at all when hot. It's not hard to start when cold, just impossible to start when hot.

IME (with cars ... Miata specifically) a tight valve makes it run rough when cold and one it warms up the alloy head expands more than the valve hardware (valve stem, bucket, shim, cam) and the valve closes fine, runs smooth when hot. I am having opposite issues here.

I'm hopeful that my missing washer and maybe missing o-ring were the root cause of my issue, but I have my doubts. Thinking about it, that o-ring doesn't make much sense because what does it seal on the screw side? A washer? I guess it's possible it seals against the neck of the needle and on the outside against the body of the carb and the washer and spring just keep it in place, but it's weird. I wonder if the bike would run a lot better with a factory-style brass cap pressed back over the idle screws after adjusting ... or even just a rubber plug. What is the leak here anyway? grr.. I need a diagram of fuel and air flow for this carb.

Okay, did not read entire thread.

Quote from: qcbaker on September 28, 2016, 11:18:45 AM
The 07 F is not really "far more complicated". Is basically the same bike, with the same engine, except with an oil cooler. And like you said, its extremely easy to just turn it into an E body type. So, if you think you can basically break even on your current bike and buy the more reliable, newer one then that definitely a viable option.

If you do end up buying the F, you can sell the fairings for a couple hundred bucks if they're in good shape.

From what I have read, it looks like the '07s have noticeably more complicated carbs. Dunno when they switched. It's not just the carbs but it's sensors etc. But this bike is reportedly reliable and running right today.

The fairings on it are mint as far as I can tell from the pictures. But the seller has not gotten back to me, my guess is it's gone. If I hear back, I think I'm just going to go buy it.

Well, it wouldn't start today. I finally ran the battery low enough that it was guaranteed to not start. It's on the charger now. It may start and run again with minimal tinkering, who knows.

I have an appointment to look at the '07 GS500F tomorrow. I am pretty much ready to give up on the '92. We'll see how it goes. I may have taken my farewell ride on the '92. I will have only ridden less than 20 miles on it total if I sell it, that's in about 2 months.

wow, $1000 for a 2007 with under 3k?  that's pretty darn amazing for price granted it doesn't have a country of gremlins living on it.  I paid 2000 for my 2007 with 5k miles on it and the bike KBBs for 2450,  so yeah,  if the bike runs well, doesn't make a bunch of noise and passes a good thorough inspection, i'd be all over that.  at that price, i'd buy it just to have a 2nd bike and a parts bike should one go down. good luck man

I hate to say it, but I'd go with the '07. I bought an '09 in Feb. for $1,700, and thought I was getting a pretty good deal. I'm probably up to $2,000 into it, and it's finally running the way it should...if only it would quit raining.

I admire your efforts, but if you think you can get your money back out of the '92 (which you probably can), buying the newer bike is probably the way to go. I know there are some differences starting with the '04 models, but I don't think the newer ones are much more complicated than the older models.

FWIW, I went out today and tried to start it, and it won't start. I take that back, it will occasionally start with WOT, and it runs at like 400 rpm with WOT and then dies after 5 seconds. Then it won't start for a long time.

While it is trying to start, it backfires every so often, sometimes through the intake, sometimes exhaust.

Left plug came out wet with gas. After 5-second of bad running the right plug came out black.

Sounds like left carb is super rich and right carb is just somewhat rich.

Anyway, this has officially used up the last of my patience. Basically if I am going to have to put more time and money into a motorcycle, it's not going to be one that's 25 years old with 21K miles and a ton of issues. I'll start with a cleaner slate, better candidate for freshening.


EDIT---->

Somehow by a ridiculous miracle of fate I just fixed it.

It was one too many o-rings on one of the pilot needle adjusters. I pulled the needle, just to check, fuel dumped out the hole. Picked out the superfluous o-ring (one is apparently buried in there), and then put the needle back. Adjusted both carbs to 2.5 turns out. Cranked it with the throttle open to clear the flooding. It started, then after holding the throttle for about 3 seconds it started ripping up in revs and it idled at 4.5K, up to 5K with choke, even rolled down my steep driveway without surging. Turned off the choke and it wanted to idle at 3K, adjusted it down a bit, rode around my 3 mile loop a few times, adjusted the idle back down to under 2K with no issues when I got back.

And for the first time I rode up the driveway and into the garage without it dying at the top.

Turned it off and restarted it easily with the engine hot. In case I was going nuts I did it again, turned off and restarted, no sweat.

It still has a hair of a hanging idle so it probably is still a touch lean but man, how nuts that the thing actually runs.

I'm still going to look at the '07, leaving in like 5 minutes. I still will likely buy it and sell the '92, but at least I will be selling a RUNNING GS500E! Or if the '07 doesn't work out then I'll have something that works.

Dang. That was weird.

Quote from: mr72 on September 29, 2016, 11:12:18 AM
FWIW, I went out today and tried to start it, and it won't start. I take that back, it will occasionally start with WOT, and it runs at like 400 rpm with WOT and then dies after 5 seconds. Then it won't start for a long time.

While it is trying to start, it backfires every so often, sometimes through the intake, sometimes exhaust.

Left plug came out wet with gas. After 5-second of bad running the right plug came out black.

Sounds like left carb is super rich and right carb is just somewhat rich.

Anyway, this has officially used up the last of my patience. Basically if I am going to have to put more time and money into a motorcycle, it's not going to be one that's 25 years old with 21K miles and a ton of issues. I'll start with a cleaner slate, better candidate for freshening.


EDIT---->

Somehow by a ridiculous miracle of fate I just fixed it.

It was one too many o-rings on one of the pilot needle adjusters. I pulled the needle, just to check, fuel dumped out the hole. Picked out the superfluous o-ring (one is apparently buried in there), and then put the needle back. Adjusted both carbs to 2.5 turns out. Cranked it with the throttle open to clear the flooding. It started, then after holding the throttle for about 3 seconds it started ripping up in revs and it idled at 4.5K, up to 5K with choke, even rolled down my steep driveway without surging. Turned off the choke and it wanted to idle at 3K, adjusted it down a bit, rode around my 3 mile loop a few times, adjusted the idle back down to under 2K with no issues when I got back.

And for the first time I rode up the driveway and into the garage without it dying at the top.

Turned it off and restarted it easily with the engine hot. In case I was going nuts I did it again, turned off and restarted, no sweat.

It still has a hair of a hanging idle so it probably is still a touch lean but man, how nuts that the thing actually runs.

I'm still going to look at the '07, leaving in like 5 minutes. I still will likely buy it and sell the '92, but at least I will be selling a RUNNING GS500E! Or if the '07 doesn't work out then I'll have something that works.

Dang. That was weird.

Great to hear that you fixed it, finally! 

Why buy the 07 if you got yours running correctly now?

I went and looked at the '07. It was in pieces when we got there to look at it. After half an hour of helping the owner try to get the battery connected etc. we finally jump started it from my Jeep and it refused to idle and died constantly. Basically mechanically no better than the bike I have, and frankly for a 9 year old bike with only 3K miles on it, it was in no better shape than my old one. Dents, laid down several times on both sides, you name it.

I made a low-ball offer, they balked, I passed.

So then, I came home and my old '92 started right up. We hung around and let it run for a few minutes until it was partly warmed up, turn off, then it started right back again. No sweat. Half an hour later I went out and fired it right up, rode it for 20 minutes, worked like a champ, did a little more fine adjusting of the idle, and when I got home it was idling perfectly at 1300-1500 rpm or so and then restarted when it was hot.

I think I have the gremlins tamed for the time being.

So, the old girl came through. She didn't want to get tossed for a newer model. I think she's got the potential to be a keeper. She's sure putting on a good show this afternoon.

My dad wants me to do a ride with him this weekend into the back roads to a little town about 20 miles away or so, so this will be a big excursion. I think the GS will do it.

Man. Talk about a big 180. My old bike must be reading this forum.

  for the '92 !!!

Congrats mr72 

Indeed  !!!
Mate, that's excellent news.
Reaffirms my faith in tenacity.

Just adding on here. There are actually some things I learned in this process and I realized that I mostly came here to the forum to describe symptoms and ask for help, but I didn't mention what I learned that worked.

So just a quick recap, for those in the future who may stumble upon this thread with similar problems of their own.

With the original carbs, there was an array of problems that caused my original symptoms. It's hard to track down exactly what caused what since the behavior was very erratic, but here's what I found:

• "little o-rings" that seal the vacuum ports were missing -- this causes a major vacuum leak
• vacuum ports were broken off and improperly sealed -- even with new "little o-rings" this caused a major vacuum leak
• intake boots o-rings were hard, brittle and flat -- this caused a major vacuum leak
• float o-rings were shot -- this caused a major fuel leak into the carb bowls and inconsistent float level
• float needle seat o-rings also shot -- further causing a major fuel leak and bad float level
• pilot/idle needle o-rings were bad, which caused inability to correctly idle or set idle mixture even when other things were fixed
• some other undiagnosed problems on the carbs prompted me to replace them -- most likely more vacuum leaks and whatever o-rings I did not change were bad

All in all, these carbs were just done in. That's the long and short of it. One could potentially rebuild and nurse them back to health but it wouldn't be worth it.

I bought a set of replacement [used] carbs and then proceeded to make mistakes in addition to other issues that led to recurrence of similar symptoms. Here's the run-down.

• replacement carbs had been sitting and had misc. corrosion and clogs, most of which I cleaned and cleared before first installation. After I installed them the first time, I discovered the pilot jets were still clogged and the float level was wrong, so I replaced both jets in both carbs and adjusted the float height twice.
• most o-rings were in pretty good shape but I replaced them anyway.
• one of the float needles was sticking so I put the float needles and seats from the original carbs into the replacements
• first installation indicated I still had a vacuum leak, it was a crack in the petcock vacuum hose.
• due to my OCD about the pilot mixture needles' potentially bad o-rings, I removed them to inspect, finding they were in good shape, I put it back together but left out one of the washers. The bike ran right one time when it was put together this way but the carb on that side didn't seem to respond to any idle mixture adjustment. Then it would not start again.
• when I fixed the missing washer on the pilot needle, my OCD about o-rings kicked in again and I replaced the o-ring on that needle while it was out. Then for good measure I checked the other carb to ensure that the washer and o-ring were on that needle. The washer was there but I couldn't get an o-ring to come out with the carbs still on the bike, and I wrongly assumed it was missing so I added one and put it together. After this, the bike wouldn't start. The carb with the extra o-ring on the needle valve was flooding.
• when I removed the extra o-ring from the pilot needle that apparently had two on it and put it back together, the bike runs perfectly. If I had left the pilot needles alone on the replacement carbs rather than checking them and introducing my own mistakes, it would have worked fine from the start

I learned a ton about vacuum leaks and the pilot screws when working on this, and I'll post new threads on that. I just wanted to tie this one up.