I'll apologize up front for such a long post.... but, I wanted to be clear.
I have a stock '93 with 15k that I've owned since 1998, the only aftermarket piece is a foam air filter. I moved to the city about 4 years ago. While there I realized that the combination of poor roads and city traffic weren't the right fit for me to ride, so after the first 2 years the bike was shelved for about 2 years. I took all the precautions I knew how. I emptied the tank, shy of 1 gallon, put STABIL in the tank, road it for about 20 minutes, pulled the battery, and stored it.
Then I moved out of the city about 9 months ago. Once I pulled the bike out and put the battery in that had been trickle charging for 2 years, the bike road pretty well. I flushed the tank with new gas and the old girl moved well, shy of some sluggishness off of the line. At that point I only road it for 2 weekends. With the move and all things were hectic, and I just now pulled the bike out again last month.
At first the bike was dead. There was no life in the battery so I replaced it. The bike would start up without issue with the choke out the whole way, but
4 out of 5 times I would pull the throttle, the bike would do nothing. The other time out of 5, the bike would rev up as normal. When it would rev, it would feel very strong; I don't have any tools to show it but my layman perception was that the engine had full compression, was breathing well, had fuel, and had spark. But again that was only 1 out of 5 times I would pull the throttle..... anything but safe. The bike also didn't like having anything but full choke at all times.
So, here's what steps I have taken to try and correct this:
- 1. Replaced the gas. EFFECT: No noticeable change.
- 2. Replaced the inline fuel filter between the petcock and the carbs, after pulling the air box. EFFECT: No noticeable change, but maybe a little rougher idle.
- 3. "Rebuilt" the carbs, mostly just dismantled, cleaned, and inspected. In my feeble understanding, I thought the carbs would be fouled since I could notice what looked to be varnish in the air box. I rebuilt the carbs, but they were very clean inside, no issues with any consumables, gaskets, o-rings, plastics, etc. I reassembled the carbs and fitted them back on without balancing. EFFECT: No noticeable change.
- 4. Changed the oil and filter. EFFECT: No noticeable change after my terrible luck with the oil filter cover bolts.
- 5. Changed the spark plugs. EFFECT: No noticeable change.
- 6. Replaced the noticeably worn fuel line between the tank and the petcock. EFFECT: No noticeable change.
- 7. Fiddled with the idle screw. EFFECT: I could only get 2 conditions, bike either ran as it always had or wouldn't run/start at all.
- 8. Reinstalled the air box after reading on this site today that the bike does not like to run without it. EFFECT: The bike is back to its original temperment of starting / idleing fine, but does not like to go over 4k except every once in a while after revving the throttle a few times.
So, as you can see, I'm out a couple weeks of aggravation, maybe $100, and I'm exactly where I started. The only thing the bike does well is start; starts like a champ every time. The only thing it does OK is running once you've gotten it past 4k, e.g. I took it around the block and after revving the throttle a couple times and getting nothing, the bike will go eventually (after a wheelie...) and once it goes, it goes well -- I can rev to redline, shift and shift with no problems, but it all starts over again when I stop. Here's what it does poorly: idle, run without the choke, and rev.
Sorry again for the long post, but I wanted to be clear.
Here's what I can think to try next, what does everyone think:
- A. Replace all fuel lines.
- B. Pull tank's petcock and check screen / check fuel flow through out the system.
- C. Check spark plug wires / bike electrical relays.
- D. Check the boots between the carbs and the engine.
- E. Balance the carbs.
- F. Whatever anyone else can come up with....
What does everyone think? Thanks in advance![/list]
First replace the air filter with a stock one.Beware that there is an air filter floating around that is supposed to be a replacement but in fact chokes the bike out causing the conditions you have listed.I would pull the carbs again and use spray cleaner in all the passages and jets.That is where crud and varnish builds up and causes problems.Next I would adjust the valves before balancing the carbs.This way the carbs are receiving all the vacuum that the engine produces.It wouldn't hurt to pull the frame petcock and check it for dirt and debris.Remember to start the bike on PRIme then switch to ON.If the vacuum operation is bad it will have difficulty running in the ON or RES position.I'm posting some links for reference.
http://cgi.stanford.edu/~sanjayd/gs500/Upgrades/AirFilter
http://gstwin.com/carb_work.htm
http://www.bbburma.net/FloatHeight.htm
http://video.google.com/videoplay?docid=-2015554469142545363&q=suzuki+gs500
http://cgi.stanford.edu/~sanjayd/gs500/Maintenance/5CarbSync
http://gstwins.com/gsboard/index.php?topic=19363.0
http://gstwins.com/gsboard/index.php?topic=36958.0
Thank you for the suggestions and the links. I'd like to try all the non-invasive things first since the bike was running "fine" 7 months ago.
1. The current air filter has worked fine in the past and been cleaned many times -- do you think I should still swap it out?
2. Which passages are you thinking of in the carbs? They were both just dismantled and cleaned. The only thing I can think that I didn't thoroughly clean was the T-joint for the fuel, between the carbs.
3. Valves -- I will check these last, I guess. I'm still mystified how these are different from the bike running fine 7 months ago...
4. Petcock -- I'll try this tonight. Currently the bike runs on both PRIME and ON. What about the tank petcock?
Thanks again. Any more suggestions would be greatly appreciated...
Quote from: pennstump on June 16, 2008, 04:34:44 PM
Thank you for the suggestions and the links. I'd like to try all the non-invasive things first since the bike was running "fine" 7 months ago.
1. The current air filter has worked fine in the past and been cleaned many times -- do you think I should still swap it out?
2. Which passages are you thinking of in the carbs? They were both just dismantled and cleaned. The only thing I can think that I didn't thoroughly clean was the T-joint for the fuel, between the carbs.
3. Valves -- I will check these last, I guess. I'm still mystified how these are different from the bike running fine 7 months ago...
4. Petcock -- I'll try this tonight. Currently the bike runs on both PRIME and ON. What about the tank petcock?
Thanks again. Any more suggestions would be greatly appreciated...
The foam filters start to break down over time and become a restriction.If it's still soft it should be ok.The passages where the 2 jets are located inside the float bowls.The upper T can get clogged.This would slow or stop the flow of fuel into the carb bowls.The tank petcock has a screen.It could be blocked.It's a long shot but possible.It could be low float height not letting in enough fuel at upper rpms.
Quote from: pennstump on June 15, 2008, 06:35:06 PM
I'll apologize up front for such a long post.... but, I wanted to be clear.
I have a stock '93 with 15k that I've owned since 1998, the only aftermarket piece is a foam air filter. I moved to the city about 4 years ago. While there I realized that the combination of poor roads and city traffic weren't the right fit for me to ride, so after the first 2 years the bike was shelved for about 2 years. I took all the precautions I knew how. I emptied the tank, shy of 1 gallon, put STABIL in the tank, road it for about 20 minutes, pulled the battery, and stored it.
As far as I know, it's best to store the bike with a full tank. The exposed surfaces of an empty tank are prone to rusting. Have you looked taken a look at the condition inside the tank? Maybe rust has formed and is contaminating the fuel?
Was the bike stored in a garage? Outdoors and covered? Outdoors and exposed?...
Quote
Then I moved out of the city about 9 months ago. Once I pulled the bike out and put the battery in that had been trickle charging for 2 years, the bike road pretty well. I flushed the tank with new gas and the old girl moved well, shy of some sluggishness off of the line. At that point I only road it for 2 weekends. With the move and all things were hectic, and I just now pulled the bike out again last month.
At first the bike was dead. There was no life in the battery so I replaced it. The bike would start up without issue with the choke out the whole way, but 4 out of 5 times I would pull the throttle, the bike would do nothing. The other time out of 5, the bike would rev up as normal. When it would rev, it would feel very strong; I don't have any tools to show it but my layman perception was that the engine had full compression, was breathing well, had fuel, and had spark. But again that was only 1 out of 5 times I would pull the throttle..... anything but safe. The bike also didn't like having anything but full choke at all times.
I'm fairly certain that two years of sitting is beyond the shelf life of Stabil. At that length of time, I would expect to see some varnish or some gummed-up fuel. I see below that you took apart the carbs and cleaned them; is it possible that you missed a blockage in one of the tiny passages?
How many miles did you put on in those two weekends you took the bike out?
Quote
So, here's what steps I have taken to try and correct this:
- 1. Replaced the gas. EFFECT: No noticeable change.
- 2. Replaced the inline fuel filter between the petcock and the carbs, after pulling the air box. EFFECT: No noticeable change, but maybe a little rougher idle.
- 3. "Rebuilt" the carbs, mostly just dismantled, cleaned, and inspected. In my feeble understanding, I thought the carbs would be fouled since I could notice what looked to be varnish in the air box. I rebuilt the carbs, but they were very clean inside, no issues with any consumables, gaskets, o-rings, plastics, etc. I reassembled the carbs and fitted them back on without balancing. EFFECT: No noticeable change.
- 4. Changed the oil and filter. EFFECT: No noticeable change after my terrible luck with the oil filter cover bolts.
- 5. Changed the spark plugs. EFFECT: No noticeable change.
- 6. Replaced the noticeably worn fuel line between the tank and the petcock. EFFECT: No noticeable change.
- 7. Fiddled with the idle screw. EFFECT: I could only get 2 conditions, bike either ran as it always had or wouldn't run/start at all.
- 8. Reinstalled the air box after reading on this site today that the bike does not like to run without it. EFFECT: The bike is back to its original temperment of starting / idleing fine, but does not like to go over 4k except every once in a while after revving the throttle a few times.
Looks like a good list of restoration stuff.
Quote
So, as you can see, I'm out a couple weeks of aggravation, maybe $100, and I'm exactly where I started. The only thing the bike does well is start; starts like a champ every time. The only thing it does OK is running once you've gotten it past 4k, e.g. I took it around the block and after revving the throttle a couple times and getting nothing, the bike will go eventually (after a wheelie...) and once it goes, it goes well -- I can rev to redline, shift and shift with no problems, but it all starts over again when I stop. Here's what it does poorly: idle, run without the choke, and rev.
If the bike ran well before, and now it doesn't, I have to think it's a carb problem. Especially considering your probably is mostly at low revs. I would suggest taking off the carbs again (I know it's a pain :() and giving the cleaning another try. You didn't mention what you did for cleaning: I would spray some carb cleaner and even use some guitar wire to clean out the passages.
If you don't wanna go through that hassle again, you could always try Seafoam? (in my opinion, I don't mind using the stuff, but I prefer to know the bike runs well without it).
Quote
Sorry again for the long post, but I wanted to be clear. Here's what I can think to try next, what does everyone think:
- A. Replace all fuel lines.
- B. Pull tank's petcock and check screen / check fuel flow through out the system.
- C. Check spark plug wires / bike electrical relays.
- D. Check the boots between the carbs and the engine.
- E. Balance the carbs.
- F. Whatever anyone else can come up with....
A. Unless they're leaking, I wouldn't replace the fuel lines just yet. I don't think fuel lines could cause the problems you describe.
B. It's a good idea to check the tank petcock, but again I don't think this is the source of your problem. If I understood correctly, once you get past the low-rev bogging, the bike runs well at high revs. I think a clogged fuel filter would cause more problems at high revs.
C. I definitely wouldn't start chasing electrical gremlins until I'd sorted out the more typical problems with taking a bike out of storage (i.e. carb gunk)
D. Good idea, but leaky boots would cause the bike to run lean and idle high. A problem here wouldn't lead to bogging.
E. Sure, but it's hard to balance the carbs if the bike isn't running well. Also, I don't think the carbs could get unbalanced during the 2 years in a garage.
I agree with ben2go that sitting may have caused the frame petcock to go bad; however, I still don't think that is the source of the problem. If the petcock was bad, the problem would be worse at high rpm.
Similarly, valve clearance adjustment is a good idea, but I'd exhaust other avenues first. It seems unlikely that valves would go out of spec while the bike is parked.
Out of curiosity, how are your float heights? Use this easy method to check (it also confirms that the fuel system is working to get fuel to the carbs):
http://www.bbburma.net/FloatHeight.htm
p.s. This is the first time I've looked at this thread because I thought the title suggested you were looking at advice on the next great modification you should pursue (as in new exhaust vs. LED taillight etc). Changing the title to include "troubleshooting" or "carb problem" might help get some interest from more of the experts (in addition to ben2go, that is).
Thank you for your response. I changed the title to include "TROUBLESHOOTING."
The tank really seems pretty good, little to no rust inside. The bike was stored in a garage, covered.
I agree. STABIL probably broke down, but it ran fine after the 2 years. No noticeable varnish except in the bottom of the air box, but I can't be sure that's recent. I totally could have missed something, but I tried to be pretty thorough. The only thing I think I missed was the t-valve, it probably only got some blasts from the carb cleaner. Everything else I either brushed, sprayed with carb cleaner, soaked in carb cleaner, or ran some craft wire through to remove particles. I probably put about 80 miles on in the 2 weekends.
I'm not totally familiar with Seafoam except for seeing people complaining about it on this board. Is it something more than a gas additive?
Tonight, I decided to check the tank petcock. I pulled the tank and while holding it over my gas can, I opened the petcock. Fuel moved steadily out of the reserve (longer) tube, but nothing came out of the on (shorter) tube. I have about a gallon in the tank -- is that right? Should nothing come out of the shorter tube? i then took the petcock out and inspected the screen and gasket, looked OK.
I will definitely check the float height tomorrow after work. Can I use a run off tube from a brand new battery?
when you cleaned/rebuilt carbs, did you soak/clean em? or spray or jusr r&r of needles and such?, lemme know, then ill help you some more
Quote from: pennstump on June 16, 2008, 10:15:20 PM
I agree. STABIL probably broke down, but it ran fine after the 2 years. No noticeable varnish except in the bottom of the air box, but I can't be sure that's recent. I totally could have missed something, but I tried to be pretty thorough. The only thing I think I missed was the t-valve, it probably only got some blasts from the carb cleaner. Everything else I either brushed, sprayed with carb cleaner, soaked in carb cleaner, or ran some craft wire through to remove particles. I probably put about 80 miles on in the 2 weekends.
On the scale of fuel passages, the t-valve is pretty big. It's worth checking, but if it was blocked I would expect problems at all rpm :dunno_white: Buddha's the one who could tell you which jets and passages you should focus on with low rpm trouble. My money's on the carbs needing another cleaning.
Quote
I'm not totally familiar with Seafoam except for seeing people complaining about it on this board. Is it something more than a gas additive?
It's supposed to be a cure-all cleaner. If there are any deposits blocking carb passages, the Seafoam may help to clean them out.
Quote
Tonight, I decided to check the tank petcock. I pulled the tank and while holding it over my gas can, I opened the petcock. Fuel moved steadily out of the reserve (longer) tube, but nothing came out of the on (shorter) tube. I have about a gallon in the tank -- is that right? Should nothing come out of the shorter tube? i then took the petcock out and inspected the screen and gasket, looked OK.
RES holds about 1 gallon, so your results sound as expected. Now that you mention it, first thing I would do is add more gasoline to that tank. Normally I'd suggest filling it, but since you will likely need to remove it a couple more times, maybe just half way?
Quote
I will definitely check the float height tomorrow after work. Can I use a run off tube from a brand new battery?
I've never seen a clear battery vent tube. If yours is clear and brand new, I guess it would be fine. Seems unnecessary though, given that you can buy clear tubing anywhere for 10 cents a foot. :icon_mrgreen:
Quote from: yamahonkawazuki on June 16, 2008, 11:13:21 PM
when you cleaned/rebuilt carbs, did you soak/clean em? or spray or jusr r&r of needles and such?, lemme know, then ill help you some more
I brushed the large sections, sprayed all non-plastic bits with carb cleaner, soaked the jets, needles, and bowls in carb cleaner, and ran some craft wire through "all" small passages to remove particles. The only exception being the fuel T-valve, since it was plastic and didn't want to run too much carb cleaner through it but it probably got its share of it.
any progress?
Ok... some progress after some free time today.
Here's what I did, in order:
- 1. Checked float balance via "tube method." All appears to be good, precisely at the bowl seal.
2. Drained tank and pulled tank petcock. Appeared fine, very little to no rust, but cleaned with compressed air.
3. Pulled frame petcock and cleaned. I don't know if this was bad, but I removed the screws and used a good bit of force to remove the vacuum plate and expose the baffle. All looked good, but I simply re-attached the plate with the damaged gasket. (later on this appears to not be an issue)
4. Checked fuel flow through the fuel system, e.g. the tank was hooked back up and I replaced the tube from my inline fuel filter to the carb T-joint with a length of scrap tubing and into my gas can. The flow seemed to be more than adequate.
5. Replaced all fuel lines after ripping one while removing it from the tank.
6. Replaced the vacuum line from the petcock to the carbs after I noticed a small hole in the tube. EFFECT: Well, no real effect, but my bike now runs on RESERVE and ON settings.
7. Noticed that periodically some "exhaust" would come out the air intakes of the carbeurators. I don't have a clue why this is happening exactly, but I think it's not good.
8. Pulled the carbs and visually inspected the boots.
9. Pulled the bowls off of the carbs and recleaned and inspected everything. I now made it a point to spray out the 2 T-joints, jets, etc. There were 2 things of substance: when I pulled the right bowl, there was "sludge" at the bottom. The left bowl was clean. The sludge was fairly gelatinous. My only guess was that it had something to do with the oil I used to lubricate the slides and o-rings. I cleaned it out. The other interesting thing is that I paid a little more attention to the bypass ports directly under the butterfly valve. I noticed that light was only shining through a couple of the holes. I cleaned it out with some fine wire and sprayed some cleaner on it. I have read many times on this site about the idle screw. I moved it until it started to touch the throttle, then spun the screw 2.5 revolutions.
9. Reassembled everything, minus air box, for some testing. The engine seemed more "flickable" now, but ran quite poorly around the block once it was assembled. I cannot explain why, but the bike seemed to operate well only at about 1/3 throttle and the bike would sit at about 4k RPMs. At any other throttle point, the bike would severely hesitate and buck.
10. Reinstalled the air box, making sure the boots where on the carbs. I could tell it was running better, even without the air filter, yet. If I placed my hand over the filter hole, the bike would accelerate quickly and strongly, suggesting too much air flow before. I then installed the air filter, nothing again that covering the opening with my hand would make the bike's engine accelerate very smoothly and evenly.
11. Test drove the bike and now the issue with the bike only taking off 1 out of 5 times is gone. Hooray... :cheers: for a second. Now, the bike severely hesitates until about 4000 - 4500 RPMs, then the bike takes off and runs without issues. Also, the bike does not run with the choke off. I tried to adjust the choke while playing with the idle screw. The bikes seems to periodically surge on its own. While the choke was engaged, either the whole way or only partial way, I could only ever adjust the idle to be between 2000 and 4000. Getting below 2000 would make the bike stall immediately. The bike was clearly warmed up for all of this testing.
So, here I am. I have a bike that runs perfectly well over 4500 RPMs, stutters and hesitates below 4500 RPMs, and cannot run without the choke. I, again, would love for anyone to offer their thoughts on my predicament. Tomorrow, I plan to check for vacuum leaks with some ether around the carbs and boots.
Here are some questions I have:
A. Are there any secrets to replacing the throttle cable on the carbs? Should the throttle cable be taut?
B. The choke seems take a little more effort to move now; anything to worry about?
C. The boots between the air box and the carbs have tension rings on them, but they do not do anything with my setup. When fully screwed in, they still spin and move around. Is that in any way normal?
D. Is there anything to be concerned about with the "exhaust" blowing out of the carbs?
E.
What should I do now?Thanks again for everyone's help and I apologize again for the long-winded post...
have you dissassembled, and toroughly CLEANED the carbs?, i see you removed, inspected and replaced them, but saw nothing of you cleaning them, also are teh butterflies at teh same level?
Well, you're not done yet, but it certainly looks like you've made some progress! :thumb: And kudos for posting such extensive details on your troubleshooting procedure.
Quote from: pennstump on June 24, 2008, 12:49:36 AM
1. Checked float balance via "tube method." All appears to be good, precisely at the bowl seal.
2. Drained tank and pulled tank petcock. Appeared fine, very little to no rust, but cleaned with compressed air.
3. Pulled frame petcock and cleaned. I don't know if this was bad, but I removed the screws and used a good bit of force to remove the vacuum plate and expose the baffle. All looked good, but I simply re-attached the plate with the damaged gasket. (later on this appears to not be an issue)
4. Checked fuel flow through the fuel system, e.g. the tank was hooked back up and I replaced the tube from my inline fuel filter to the carb T-joint with a length of scrap tubing and into my gas can. The flow seemed to be more than adequate.
5. Replaced all fuel lines after ripping one while removing it from the tank.
6. Replaced the vacuum line from the petcock to the carbs after I noticed a small hole in the tube. EFFECT: Well, no real effect, but my bike now runs on RESERVE and ON settings.
OK. All of this looks good. Seems like we can safely assume there is no problem getting fuel to the carbs!
Quote
7. Noticed that periodically some "exhaust" would come out the air intakes of the carbeurators. I don't have a clue why this is happening exactly, but I think it's not good.
This is strange. Maybe a problem with timing or valve clearances? I seem to recall that you said the bike ran well prior to storage, so it would be strange that timing or valves would have changed. :icon_confused:
Quote
8. Pulled the carbs and visually inspected the boots.
9. Pulled the bowls off of the carbs and recleaned and inspected everything. I now made it a point to spray out the 2 T-joints, jets, etc. There were 2 things of substance: when I pulled the right bowl, there was "sludge" at the bottom. The left bowl was clean. The sludge was fairly gelatinous. My only guess was that it had something to do with the oil I used to lubricate the slides and o-rings. I cleaned it out. The other interesting thing is that I paid a little more attention to the bypass ports directly under the butterfly valve. I noticed that light was only shining through a couple of the holes. I cleaned it out with some fine wire and sprayed some cleaner on it.
Carb sludge is bad. If the sludge was in the bowl, it was probably in the carb passages also. This was the kind of gunk that would be expected in a sitting bike. And the same kind of gunk that would cause the running problems you described inititally. Good thing you cleaned it out now! :icon_mrgreen:
Quote
I have read many times on this site about the idle screw. I moved it until it started to touch the throttle, then spun the screw 2.5 revolutions.
EDIT: I'm not sure what you are talking about here :dunno_white: :icon_confused:
Are you talking about the pilot screw? 2.5 turns sounds like one of the mixture screws - those are different than the idle screw. The idle screw is a big brass knob that hangs down between the two carbs.
(http://www.bbburma.net/MiscFotos/DSCF2431_Idle_Drain_Mixture_Screws.jpg)
The idle is not set according to any number of turns. The idle is set strictly based upon rpm (1200 rpm +/- 100 rpm)
This thread has some relevant details (I stole the picture from Kerry :)):
http://gstwins.com/gsboard/index.php?topic=11433.msg95450#msg95450
Quote
9. Reassembled everything, minus air box, for some testing. The engine seemed more "flickable" now, but ran quite poorly around the block once it was assembled. I cannot explain why, but the bike seemed to operate well only at about 1/3 throttle and the bike would sit at about 4k RPMs. At any other throttle point, the bike would severely hesitate and buck.
10. Reinstalled the air box, making sure the boots where on the carbs. I could tell it was running better, even without the air filter, yet. If I placed my hand over the filter hole, the bike would accelerate quickly and strongly, suggesting too much air flow before. I then installed the air filter, nothing again that covering the opening with my hand would make the bike's engine accelerate very smoothly and evenly.
Without the air box, your bike should run much too lean (i.e. too much air in the air-fuel mixture). I think it would be tough to assess how well the bike is running with the airbox removed. This seems to be confirmed by the note that the bike ran better when you restricted the airflow.
Quote
11. Test drove the bike and now the issue with the bike only taking off 1 out of 5 times is gone. Hooray... :cheers: for a second. Now, the bike severely hesitates until about 4000 - 4500 RPMs, then the bike takes off and runs without issues. Also, the bike does not run with the choke off. I tried to adjust the choke while playing with the idle screw. The bikes seems to periodically surge on its own. While the choke was engaged, either the whole way or only partial way, I could only ever adjust the idle to be between 2000 and 4000. Getting below 2000 would make the bike stall immediately. The bike was clearly warmed up for all of this testing.
So, here I am. I have a bike that runs perfectly well over 4500 RPMs, stutters and hesitates below 4500 RPMs, and cannot run without the choke. I, again, would love for anyone to offer their thoughts on my predicament. Tomorrow, I plan to check for vacuum leaks with some ether around the carbs and boots.
Because the bike will not run without choke, it seems there may be an air leak - the extra fuel from the choke would be necessary to enrich the mixture :dunno_white: The high idle (impossible to lower) also suggests a lean mixture. At this point, I would focus on identifying air leaks and making sure the choke is operating correctly.
Quote
Here are some questions I have:
A. Are there any secrets to replacing the throttle cable on the carbs? Should the throttle cable be taut?
Not sure what you mean. The throttle cable has an outer sheath (the black stuff) and a wire cable inside. The sheath should not be taught; it needs some give so that the cable doesn't bind when you turn the handlebars. The cable inside should slide freely; when you twist the throttle, the movement should be smooth.
Quote
B. The choke seems take a little more effort to move now; anything to worry about?
You may want to remove and lubricate the choke cable. There is a special tool for this, or you can hang the cable and let lubricating oil flow through it. Also, check that the choke plunger (in the carb) is moving freely in-and-out when you move the choke lever.
Quote
C. The boots between the air box and the carbs have tension rings on them, but they do not do anything with my setup. When fully screwed in, they still spin and move around. Is that in any way normal?
This is not normal. The point of the rings is to seal the intake boot and prevent air leaks. Perhaps the previous owner replaced these with a non-stock size? I would definitely spray some starting fluid or WD-40 around here to determine if there is an air leak.
Quote from: pennstump on June 24, 2008, 12:49:36 AM
Ok... some progress after some free time today.
Here's what I did, in order:
- 1. Checked float balance via "tube method." All appears to be good, precisely at the bowl seal.
2. Drained tank and pulled tank petcock. Appeared fine, very little to no rust, but cleaned with compressed air.
3. Pulled frame petcock and cleaned. I don't know if this was bad, but I removed the screws and used a good bit of force to remove the vacuum plate and expose the baffle. All looked good, but I simply re-attached the plate with the damaged gasket. (later on this appears to not be an issue)
4. Checked fuel flow through the fuel system, e.g. the tank was hooked back up and I replaced the tube from my inline fuel filter to the carb T-joint with a length of scrap tubing and into my gas can. The flow seemed to be more than adequate.
5. Replaced all fuel lines after ripping one while removing it from the tank.
6. Replaced the vacuum line from the petcock to the carbs after I noticed a small hole in the tube. EFFECT: Well, no real effect, but my bike now runs on RESERVE and ON settings.
7. Noticed that periodically some "exhaust" would come out the air intakes of the carbeurators. I don't have a clue why this is happening exactly, but I think it's not good.
8. Pulled the carbs and visually inspected the boots.
9. Pulled the bowls off of the carbs and recleaned and inspected everything. I now made it a point to spray out the 2 T-joints, jets, etc. There were 2 things of substance: when I pulled the right bowl, there was "sludge" at the bottom. The left bowl was clean. The sludge was fairly gelatinous. My only guess was that it had something to do with the oil I used to lubricate the slides and o-rings. I cleaned it out. The other interesting thing is that I paid a little more attention to the bypass ports directly under the butterfly valve. I noticed that light was only shining through a couple of the holes. I cleaned it out with some fine wire and sprayed some cleaner on it. I have read many times on this site about the idle screw. I moved it until it started to touch the throttle, then spun the screw 2.5 revolutions.
9. Reassembled everything, minus air box, for some testing. The engine seemed more "flickable" now, but ran quite poorly around the block once it was assembled. I cannot explain why, but the bike seemed to operate well only at about 1/3 throttle and the bike would sit at about 4k RPMs. At any other throttle point, the bike would severely hesitate and buck.
10. Reinstalled the air box, making sure the boots where on the carbs. I could tell it was running better, even without the air filter, yet. If I placed my hand over the filter hole, the bike would accelerate quickly and strongly, suggesting too much air flow before. I then installed the air filter, nothing again that covering the opening with my hand would make the bike's engine accelerate very smoothly and evenly.
11. Test drove the bike and now the issue with the bike only taking off 1 out of 5 times is gone. Hooray... :cheers: for a second. Now, the bike severely hesitates until about 4000 - 4500 RPMs, then the bike takes off and runs without issues. Also, the bike does not run with the choke off. I tried to adjust the choke while playing with the idle screw. The bikes seems to periodically surge on its own. While the choke was engaged, either the whole way or only partial way, I could only ever adjust the idle to be between 2000 and 4000. Getting below 2000 would make the bike stall immediately. The bike was clearly warmed up for all of this testing.
So, here I am. I have a bike that runs perfectly well over 4500 RPMs, stutters and hesitates below 4500 RPMs, and cannot run without the choke. I, again, would love for anyone to offer their thoughts on my predicament. Tomorrow, I plan to check for vacuum leaks with some ether around the carbs and boots.
Here are some questions I have:
A. Are there any secrets to replacing the throttle cable on the carbs? Should the throttle cable be taut?
B. The choke seems take a little more effort to move now; anything to worry about?
C. The boots between the air box and the carbs have tension rings on them, but they do not do anything with my setup. When fully screwed in, they still spin and move around. Is that in any way normal?
D. Is there anything to be concerned about with the "exhaust" blowing out of the carbs?
E. What should I do now?
Thanks again for everyone's help and I apologize again for the long-winded post...
Not trying to ruffle ya feathers but some of us have a light blue back ground and can't read the yellow text.Sorry for any trouble. :cry:
Quote from: ben2go on June 24, 2008, 08:26:26 AM
Not trying to ruffle ya feathers but some of us have a light blue back ground and can't read the yellow text.Sorry for any trouble. :cry:
I had the same trouble :( If you drag your cursor over the text (i.e. highlight the text), the text turns dark blue on a white background... much easier to read! :)
Quote from: beRto on June 24, 2008, 08:33:28 AM
Quote from: ben2go on June 24, 2008, 08:26:26 AM
Not trying to ruffle ya feathers but some of us have a light blue back ground and can't read the yellow text.Sorry for any trouble. :cry:
I had the same trouble :( If you drag your cursor over the text (i.e. highlight the text), the text turns dark blue on a white background... much easier to read! :)
Cool.Never thought of that.Thanks. :thumb:
Thanks guys. Sorry for the text color. I'm on the gray palette and anything else is impossible to read...
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This is strange. Maybe a problem with timing or valve clearances? I seem to recall that you said the bike ran well prior to storage, so it would be strange that timing or valves would have changed. :icon_confused:
Very strange, to make is odder, it doesn't seem to happen now.
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EDIT: I'm not sure what you are talking about here :dunno_white: :icon_confused:
Are you talking about the pilot screw? 2.5 turns sounds like one of the mixture screws - those are different than the idle screw. The idle screw is a big brass knob that hangs down between the two carbs.
The idle is not set according to any number of turns. The idle is set strictly based upon rpm (1200 rpm +/- 100 rpm)
Then I must apologize, I was overloading terms. I meant the idle screw, no wonder.... :icon_mrgreen: I still have the brass fitting over the other screw; would they need adjusting? I will check out that thread.
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Because the bike will not run without choke, it seems there may be an air leak - the extra fuel from the choke would be necessary to enrich the mixture :dunno_white: The high idle (impossible to lower) also suggests a lean mixture. At this point, I would focus on identifying air leaks and making sure the choke is operating correctly.
The only places I would think to look for air leaks would be the 2 boots between air box and carbs, the carbs themselves, and the 2 boots between the carbs and the engine. Are there any more places to look?
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A. Are there any secrets to replacing the throttle cable on the carbs? Should the throttle cable be taut?
Not sure what you mean. The throttle cable has an outer sheath (the black stuff) and a wire cable inside. The sheath should not be taught; it needs some give so that the cable doesn't bind when you turn the handlebars. The cable inside should slide freely; when you twist the throttle, the movement should be smooth.
Should the wire within the throttle cable be tight, and if not how much slack should be in the actual wire? This question now seems less important since I can now adjust the idle screw how need be from my slow moment above... :oops:
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C. The boots between the air box and the carbs have tension rings on them, but they do not do anything with my setup. When fully screwed in, they still spin and move around. Is that in any way normal?
This is not normal. The point of the rings is to seal the intake boot and prevent air leaks. Perhaps the previous owner replaced these with a non-stock size? I would definitely spray some starting fluid or WD-40 around here to determine if there is an air leak.
I will replace them and check for leaks tonight.
Thanks again, beRto.
Quote from: yamahonkawazuki on June 24, 2008, 01:33:58 AM
have you dissassembled, and toroughly CLEANED the carbs?, i see you removed, inspected and replaced them, but saw nothing of you cleaning them, also are teh butterflies at teh same level?
I've done this to the best of my abilities. I have now twice disassembled the carbs, sprayed cleaner through the passageways, used craft wire to get at the small openings, soaked the bowls and jets, and inspected all consumables and o-rings. Are there any obvious things that I may have missed? Actually, I haven't had much luck with the wire and the slow system (e.g. the small pilot hole on the bottom right of the air intake). Should I have been able to get a wire in that opening for cleaning? I chalked it up to the wire being too big, but now that I think about it... maybe it should have fit...
The butterflies look parallel to the naked eye, is there a way to test for sure?
Thanks.
Quote from: pennstump on June 24, 2008, 11:14:10 AM
Then I must apologize, I was overloading terms. I meant the idle screw, no wonder.... :icon_mrgreen: I still have the brass fitting over the other screw; would they need adjusting? I will check out that thread.
I would not remove the brass caps. Assuming the bike is stock (no aftermarket exhaust, stock airbox), it should be able to run fine with the stock settings. Granted, the bike may be stock-jetted a little lean, but certainly not so bad that it wouldn't hold an idle or allow the bike to take off from a standstill.
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The only places I would think to look for air leaks would be the 2 boots between air box and carbs, the carbs themselves, and the 2 boots between the carbs and the engine. Are there any more places to look?
Start with those places and go from there!
Another common source of air leaks (especially considering you have taken the carbs apart) is to have misplaced the tiny o-rings that fit into the top of the carbs. A search should turn up lots of threads with pictures, diagrams, fiches, etc. Ask if you don't find the right info.
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Should the wire within the throttle cable be tight, and if not how much slack should be in the actual wire? This question now seems less important since I can now adjust the idle screw how need be from my slow moment above... :oops:
The throttle cable should not be taught; there should be some free play in the throttle. You should be able to turn the throttle a few degrees before you feel the cable start to pull. The point of freeplay is so that the engine speed does not increase if you turn the handlebars (could lead to a bad result if it were to happen in a corner!).
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I will replace them and check for leaks tonight.
Sounds good
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Thanks again, beRto.
You're welcome!
Does anyone know of any images of the pilot jet? From the exploded view, I don't know that I saw it, how do you get to it?
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The only places I would think to look for air leaks would be the 2 boots between air box and carbs, the carbs themselves, and the 2 boots between the carbs and the engine. Are there any more places to look?
Start with those places and go from there!
Another common source of air leaks (especially considering you have taken the carbs apart) is to have misplaced the tiny o-rings that fit into the top of the carbs. A search should turn up lots of threads with pictures, diagrams, fiches, etc. Ask if you don't find the right info.
I found a leak at the bottom of the left boot between the carbs and the air box, no leaks at all from the carbs or, more specifically, the vacuum caps. I then replaced the hose clamps with something that could get tighter. No more leak, but no noticeable change in the engine's behavior. The bike still dies without the choke and hesitates under 4500 RPMs, even after confirming that I sprayed carb cleaner and inserted a wire into the "slow system" hole.
What else could cause the bike to die without the choke. I'm now a little fixated on the pilot jet... How can I confirm that I did check this out? Any pictures or description of where it sits? When I disassembled the carbs the first time, following the FAQ directions from this site, I was supposed to tap a hammer on the main jet (http://gstwin.com/carb_work.htm) I couldn't knock anything loose so I just soaked the hell out of it.... is the pilot jet what I was supposed to dislodge for cleaning? Time to take the carbs off again? :mad:
Thanks again.
Pilots once you remove it, usually should not be reused. They are likely to get damaged and if they do, getting it out will be a beeyatch ...
Anyway, I can rejet and trouble shoot, or sell you a jet pack for a stock bike with the right pilots in it. Usually you can make the same mistake over and over and wonder why the problem keeps comming back ...
Cool.
Buddha.
What do the sparkplugs look like?
Here's a thread with lots of details about the missing o-rings; the symptoms sound very similar to yours (you may want to take the carbs off again and recheck):
http://gstwins.com/gsboard/index.php?topic=40662.0
Image 7.8 (B) shows the pilot jet location:
(http://i216.photobucket.com/albums/cc179/gs_beRto/carbjets.gif)
I can't imagine that you missed it? :dunno_white: However, if the pilot jet is clogged, it could cause the problems you are having. Again, I would suggest looking at the carb insides another time... sorry :cry: :icon_mrgreen:
Keep trying, you'll get it!
SUCCESS!
I pulled the carbs again and after confirming what the pilot jets were and that I had removed / cleaned them before. I pulled them out again. Both came out without any issues and with no damage to either. I flipped one over... no jet hole. Then I turned the other one over... no jet hole. Both had become completely impacted with gunk. This must have happened in the last 3 weeks. Anyway, I soaked and cleaned them and the tube internal to the floats, inspected everything else, and put the carbs back together again.
Next I thoroughly inspected the carb-engine boots, no issues. Then I installed the carbs and thoroughly inspected the carb-air box boots. My best guess is that over time the carb - air box boots warped, so this is why the old hose clamps were not effective. I then very carefully installed the air box.
Start the thing up and.... perfect. I think it must have been about 3 small things and 2 big things (clogged bypass ports and pilot jet) together. Now the bike idles fine, starts fine, runs fine, if anything now the bike's throttle seems a little touchy -- maybe because I haven't ridden in a while... The only thing of note was one stop sign, the bike stalled when I went to accelerate.... it only happened once and after the last few weeks, I'm willing to write it off.
Thank you to everyone for their help, especially beRto.
Now, I guess I'm off to the front fork main seals and chain...
:cheers:
Fantastic! Another GStwin success story :thumb:
(sorry Buddha ;) :icon_mrgreen: )