Recently started working on my 1997 gs500e again. I completed basic maintenance (oil/oil filter change) carbs cleaned out, new gas etc, etc. Finally got her started and running seemingly fine. But then I go to take her for a test ride and all of a sudden around 1/2 throttle she struggles to maintain rpms or even gain rpms. Does anyone have any advice or has anyone experienced the same issue? Thanks in advance
What have you ruled out? When I put my airbox back on the rubber boots never hook under the carbs right which would cause airflow problems.
How long is the bike running before it drops revs?
Chris
O0
Especially if it happens only above a certain speed, there could be a bad seal between the airbox and carbs, or even something as simple as the breather hose routed incorrectly.
You could also have an old or fouled filter element causing a lack of airflow when you really open the throttle.
How's your jetting?
You have correct fuel hose routing ? Sounds like the floats aren't filling up.
Or a rip in a diaphragm.
Cool.
Buddha.
Quote from: the_63 on February 07, 2017, 05:23:44 PM
What have you ruled out? When I put my airbox back on the rubber boots never hook under the carbs right which would cause airflow problems.
How long is the bike running before it drops revs?
Chris
O0
That was my first guess but when I first put everything back together after I cleaned the carbs I noticed when I turned the gas tank flow back on i was losing fuel between the airbox boots and the carbs. I got the leak to stop but do you think I still don't have a good seal?
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Breather hose goes from the engine to the airbox right? Or is that the top hose on the carbs?
Jetting is completely stock. I will try cleaning the air filter out. I might have skipped that step when doing everything.
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Quote from: The Buddha on February 07, 2017, 08:11:39 PM
You have correct fuel hose routing ? Sounds like the floats aren't filling up.
Or a rip in a diaphragm.
Cool.
Buddha.
Fuel hoses are routed correctly. Double checked that because I thought that might be an issue. Where would possible rips be? Im guessing between the carbs and airbox or between carbs and the engine?
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Quote from: newbie1993 on February 07, 2017, 08:13:00 PM
Quote from: the_63 on February 07, 2017, 05:23:44 PM
What have you ruled out? When I put my airbox back on the rubber boots never hook under the carbs right which would cause airflow problems.
How long is the bike running before it drops revs?
Chris
O0
That was my first guess but when I first put everything back together after I cleaned the carbs I noticed when I turned the gas tank flow back on i was losing fuel between the airbox boots and the carbs. I got the leak to stop but do you think I still don't have a good seal?
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Also, the bike idles perfectly until I mess with the throttle. Rpms either jump drastically and stay around 4k or rise to around 6-8k and bounce around until the bike cuts off
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Quote from: newbie1993 on February 07, 2017, 08:13:00 PM
when I first put everything back together after I cleaned the carbs I noticed when I turned the gas tank flow back on i was losing fuel between the airbox boots and the carbs. I got the leak to stop but do you think I still don't have a good seal?
How did you solve this issue? Because it sounds like all you did was make sure the airbox was on the carbs tight so that the fuel didn't drip out of the boots.
Fuel should be leaving the carbs in one direction and in one state. Towards the engine, and as a vapor.
If it is leaking out the back as liquid the carbs are overflowing, even if the fuel is collecting in the air box it's still overflowing.
In which case the floats in the carbs are set improperly or the needle and seat is bad.
Diaphragms are in the carb, they're under that plastic top.
Tiny tiny rip you cant even see will do this.
Cool.
Buddha.
Quote from: Watcher on February 07, 2017, 08:47:04 PM
Quote from: newbie1993 on February 07, 2017, 08:13:00 PM
when I first put everything back together after I cleaned the carbs I noticed when I turned the gas tank flow back on i was losing fuel between the airbox boots and the carbs. I got the leak to stop but do you think I still don't have a good seal?
How did you solve this issue? Because it sounds like all you did was make sure the airbox was on the carbs tight so that the fuel didn't drip out of the boots.
Fuel should be leaving the carbs in one direction and in one state. Towards the engine, and as a vapor.
If it is leaking out the back as liquid the carbs are overflowing, even if the fuel is collecting in the air box it's still overflowing.
In which case the floats in the carbs are set improperly or the needle and seat is bad.
So as the carbs are filling with fuel while the petcock is is the prime position. I should see no fuel on the airbox side unless i have a flooding issue. And yes, all i did is get rid of the leaking issue. And I didnt bother with the needle adjustment or anything because I didnt think it needed it because they were last adjusted when i last rode and i had no flooding issues or leaking issues. And flooding would mean the bike would be running rich right?
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Think of the carbs as like tiny versions of your toilet, and the fuel line from the gas tank is like the water line coming from the wall.
You flush and the water from the tank drains, as the water level in the tank drops a float also drops, which opens a valve to let more water in.
As the tank fills and the float rises to a certain point it shuts off the valve, otherwise it would just overflow.
The carbs behave the same way, so if your carbs are leaking, or more specifically overflowing, the floats are not shutting off the fuel flow.
This can be from a float out of adjustment, which is something than can happen with age, or a bad valve. In a carb this would be the needle and seat.
Often the needle and seat are just dirty, often just the needle is faulty, and sometime an O-ring that seals the whole valve can go bad. It's hard to say what the culprit is.
But something here is to blame.
And a carb that is flowing too much fuel like this is essentially drowning itself. It might work fine on idle when vacuum is low but when you open it up it's just sucking way too much fuel and bogs the whole engine down.
Quote from: Watcher on February 07, 2017, 10:22:52 PM
Think of the carbs as like tiny versions of your toilet, and the fuel line from the gas tank is like the water line coming from the wall.
You flush and the water from the tank drains, as the water level in the tank drops a float also drops, which opens a valve to let more water in.
As the tank fills and the float rises to a certain point it shuts off the valve, otherwise it would just overflow.
The carbs behave the same way, so if your carbs are leaking, or more specifically overflowing, the floats are not shutting off the fuel flow.
This can be from a float out of adjustment, which is something than can happen with age, or a bad valve. In a carb this would be the needle and seat.
Often the needle and seat are just dirty, often just the needle is faulty, and sometime an O-ring that seals the whole valve can go bad. It's hard to say what the culprit is.
But something here is to blame.
And a carb that is flowing too much fuel like this is essentially drowning itself. It might work fine on idle when vacuum is low but when you open it up it's just sucking way too much fuel and bogs the whole engine down.
About how often do those needles in the float assembly need to be replaced? I replaced the jets recently and when i cleaned out the carbs the o rings werent bad. Everything still fit snug. And also at one point everything was fine. Throttle was good and responsive. Idle was perfect. Would the wd40 method help me out at all in this situation?
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Hard to say how long they last. Sometimes you can get away with cleaning them, but not with WD40. WD40 is a solvent and will destroy rubber.
Use something that isn't destructive, like alcohol.
Or sometimes just opening the drain screws on the bowls is enough to flush off any dirt that is clinging to the needles. You might get lucky.
I meant as far as making sure it isnt a vacuum leak. But i doubt it is. Would telling you i get quite a bit of backfiring help at all? I'll try and flush out anything that might be stuck in the there. But just in case the airbox isnt sealed quite right would that possibly solve my issue. And also a little bit more info. When i had the bike running earlier it would run fine and idle perfectly and all of a sudden rpms rise and then they fall and then the bike cuts off. But the needles are pretty new. My bike was my daily for pretty much every season.
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Best advice I ever got for rooting out vacuum leaks was a spray bottle of water.
Carb cleaner and WD-40 are both bad for rubber. Water isn't. Just instead of a rise in idle you're looking for a drop.
From here, though, I'd be taking the carbs off, opening the bowls, inspecting the needles for wear or debris, and verifying proper float height.
If all that checks out, then I'd go hunting for vacuum and other causes.
I will say that the bike would only start if i sprayed the silicone wd40 at the boots of the airbox at first. But that was before i took of the small fuel leak i had. What would worn out needles look like? And also if it float height had been previously adjusted would i have to bother with it this time?
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The GS uses rubber tipped needles, but you're looking for basically the same thing as this image.
Rings that imply wear, discoloration, or any sort of obvious debris.
(http://imagizer.imageshack.us/v2/800x600q90/923/4tGaGD.jpg) (https://imageshack.com/i/pn4tGaGDj)
No matter how recently the carbs were adjusted, it never hurts to check again.
Especially with how malleable the tabs are for setting float height they could easily have been bumped with the bowl off and been pushed out of spec.
Definitely also check that one of the diaphragms in the carburetors is not torn, pin-hole, misaligned, or deformed from contact with carb cleaner. That mid-throttle, low-rpm bogging/sputter is exactly the symptom of the slide and main needle not moving up and opening the main jet.
A severe vacuum leak could also cause this. Not having the caps on the vacuum ports, for example, or missing the o-rings in the carb tops that are under the vacuum ports could do it. It'd take a serious problem of the intake boot to do it, like the rubber part completely separated from the mounting flange for example (happened to me).
Vacuum moves the slide and main needle up by causing the rubber diaphragm to move. If the rubber diaphragm doesn't seal, won't flex, is torn, or there is a vacuum leak so it doesn't have enough vacuum on the top side to move, then the bike won't get off of the pilot jet and it'll top out at like 4K rpm and likely stall at more than about 1/4 throttle.
So if it was me, I'd pop the tank off, then take the black tops off the carbs and check the diaphragms inside. I had to replace one of mine recently because it was wrinkled.
Then I'd check that the carbs are firmly situated in the boots between engine and carbs, then I'd check the rubber boots between the carbs and airbox, make sure that there's nothing wrong there.
Breather hose goes from the breather cover to the airbox, and there's a hose that comes from the carbs that lays over the top of the airbox.
Chris
O0
Just made sure the diaphrams had no tears or pinholes or anything. Made sure the o rings were in the vacuum ports and made sure all parts for the needle that goes into the diaphram had all of its parts secured and were in the right place. Boots between the airbox and carbs are secured and tight. I supposed the next step is to check float heights because when I did everything else same issue happened. Would incorrect float height cause this issue as well? And also I'm getting ready to make sure float heights are correct. What is the correct adjustment height again?
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yes low float height could cause this problem.
Quote from: mr72 on February 08, 2017, 03:25:15 PM
yes low float height could cause this problem.
Would you happen to know correct float measurement?
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IDK look in the wiki, has detailed instructions on setting float height.
If fuel comes out of the airbox what does that mean? I had it running and throttle was responsive and rpms were going up smoothly as i gave it throttle and then all of a sudden when i decided to take the bike for a ride the rpms have trouble going up and the bike dies and now im stuck and also the battery won't maintain a charge. And my portable jump box is dead.
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What would happen if i put the hoses from the tank petcock in the wrong place on the frame petcock?
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http://wiki.gstwins.com/index.php?n=Maintenance.FloatHeight
Fuel out of the airbox means the carbs are overflowing. Overflowing carbs means the the float is set wrong or the needle/seat is dirty/worn.
Battery not maintaining a charge could just be from having to screw with the motorcycle so much. Not allowing it to run steadily for an extended period won't allow the motorcycle to recharge the battery effectively.
If the hoses from the tank go into the wrong place on the frame petcock the "on" and "res" positions could be switched around.
I'm honestly not sure what would happen if you tried to flow fuel into the out side, it might just not flow.
Here is the proper routing.
(http://www.gstwin.com/images/how_to/fuel%20hose/www_gs500_de_HoseRouting.jpg)
Have you ever used the see through fuel lines? If so, should all lines be full with fuel (i know the fuel line for prime should be) no matter what position the petcock is in?
The seats are fine and the needles are still pretty pointed on the ends and only should a small amount of wear. Im guessing that means the needles are set too high and arent closing when the float bowls are full causing fuel to overflow back into the upper parts of the carbs and back into the airbox and out of the overflow tube on the airbox.
I know how to check float heights using the tube method while the carbs are still mounted on the bike. However I dont know the measurement for correct adjustment. I would do the tube method just to be sure they are incorrect but havent had the time to get some tube. All I know is completely stock and the little tab on the floats are literally almost touching the top of the float directly above where the little tab is connected
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Quote from: Watcher on February 09, 2017, 12:34:48 AM
http://wiki.gstwins.com/index.php?n=Maintenance.FloatHeight
Fuel out of the airbox means the carbs are overflowing. Overflowing carbs means the the float is set wrong or the needle/seat is dirty/worn.
Battery not maintaining a charge could just be from having to screw with the motorcycle so much. Not allowing it to run steadily for an extended period won't allow the motorcycle to recharge the battery effectively.
If the hoses from the tank go into the wrong place on the frame petcock the "on" and "res" positions could be switched around.
I'm honestly not sure what would happen if you tried to flow fuel into the out side, it might just not flow.
Here is the proper routing.
(http://www.gstwin.com/images/how_to/fuel%20hose/www_gs500_de_HoseRouting.jpg)
Just saw your link. Much appreciated. I have vernier calipers however Im still a little confused. If I'm understanding correctly. I remove the carbs from the bike after emptying the float bowls and and everything. Flip them over, remove the float bowls and while float arms are kept free and touching the bottom ( or rather the top of the carbs body. And then using the calipers measure from the silver tab to where the float bowl gasket meets the body of the carbs and adjust the little silver tab based on its position to where the float bowl meets the carb body. And the measurement should be 14.6 mm give or take a mm
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Fuel level should be @ the top of the bowl.
Into the airbox = too high, or stuck or some issue.
Cool.
Buddha.
Here's a couple of youtubes:
https://www.youtube.com/watch?v=aiexehn33kg (https://www.youtube.com/watch?v=aiexehn33kg)
https://www.youtube.com/watch?v=PHuB1lyagKM (https://www.youtube.com/watch?v=PHuB1lyagKM)
Chris
O0
Is there a way to just measure the the distance of the metal tab from the float arm? I just feel like that would save a lot of time seeing as I have never used vernier calipers.
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Just checked float heights. Here are some pictures. Based on my current heights which are both wrong does the tab need to be adjusted up or down?
Float height in left carb
(https://uploads.tapatalk-cdn.com/20170209/6ee03265dbfab67e757e662ef2260323.jpg)
Float height in right carb
(https://uploads.tapatalk-cdn.com/20170209/a3fc3eaf823fdb5c5af0804cb9e6e466.jpg)
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Your petcock in prime when checking ???
Cool.
Buddha.
Quote from: The Buddha on February 09, 2017, 06:56:20 PM
Your petcock in prime when checking ???
Cool.
Buddha.
Should it not be in prime?
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Quote from: newbie1993 on February 09, 2017, 09:00:44 PM
Quote from: The Buddha on February 09, 2017, 06:56:20 PM
Your petcock in prime when checking ???
Cool.
Buddha.
Should it not be in prime?
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It should be, and if so, left is low, and right - well I am not sure, but it should be to the top of the bowl, and not have big air bubbles in the line.
I think I'm seeing some of those engine casting lines and not sure if its air or just the lines from that, but looks like left is waaaaaay off and right may be a mm or 3 off - both look low, leaving you leaner than Paris Hilton. Am I right ?
Cool.
Buddha.
Quote from: The Buddha on February 09, 2017, 11:34:59 PM
Quote from: newbie1993 on February 09, 2017, 09:00:44 PM
Quote from: The Buddha on February 09, 2017, 06:56:20 PM
Your petcock in prime when checking ???
Cool.
Buddha.
Should it not be in prime?
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It should be, and if so, left is low, and right - well I am not sure, but it should be to the top of the bowl, and not have big air bubbles in the line.
I think I'm seeing some of those engine casting lines and not sure if its air or just the lines from that, but looks like left is waaaaaay off and right may be a mm or 3 off - both look low, leaving you leaner than Paris Hilton. Am I right ?
Cool.
Buddha.
The right actually overflowed onto my hand. Meaning the tab is adjusted too low? And the tab on the left carb is adjusted too high or is it the other way around? And i wasnt sure if the those were air bubbles or something else. I just followed the instructions from the video in this thread about checking float heights. Im not completely up with all the technical terms so im not sure what you mean by engine line or lining. I
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And I thought overflowing into the airbox would mean i was too rich?
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Here are some brighter picture of the ones before so you can see where fuel begins in the tube and where it ends. Left you can see better but the right overflowed onto my fingers so you cant really see it that well unless you can see the fuel on my fingers and the overflow from the top of the tube near my fingers.
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Quote from: newbie1993 on February 09, 2017, 11:47:17 PM
And I thought overflowing into the airbox would mean i was too rich?
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Set your floats correctly, you may be getting blowby filling the airbox, and its likely due to the bike sitting and a few heat cycles could help cut down on that. I diagnose as I see it. If you're getting fuel in airbox, maybe the floats are getting stuck on occasion, otherwise they're lean ... or they tend to get stuck, this time they're stuck low, another time maybe stuck high.
Oh, try shaking the bike. See if the U tube levels change.
Cool.
Buddha.
How can I prevent them from getting stuck? And you're saying the needle is stuck low preventing the needle seat from being closed and letting more fuel in than needed or the other way around? Or do you mean the float arm itself?
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You need to remove the carbs, remove the float bowls and set the float height correctly using the procedure in the FAQ.
http://gstwins.com/gsboard/index.php?topic=26604.0
You don't have to use calipers for this. You can actually use a 15mm bolt head as a measurement guide.
While it's apart you inspect the float needles to ensure they don't stick, verify condition, etc. Smart money says get a new set of float needles and just replace them while it's apart.
Quote from: newbie1993 on February 10, 2017, 06:52:01 AM
How can I prevent them from getting stuck? And you're saying the needle is stuck low preventing the needle seat from being closed and letting more fuel in than needed or the other way around? Or do you mean the float arm itself?
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Diagnose it first. Don't just open and do stuff.
Cool.
Buddha.
Quote from: mr72 on February 10, 2017, 07:17:01 AM
You need to remove the carbs, remove the float bowls and set the float height correctly using the procedure in the FAQ.
http://gstwins.com/gsboard/index.php?topic=26604.0
You don't have to use calipers for this. You can actually use a 15mm bolt head as a measurement guide.
While it's apart you inspect the float needles to ensure they don't stick, verify condition, etc. Smart money says get a new set of float needles and just replace them while it's apart.
Links like these help a lot. I learn much better by actually seeing rather than from explanations using terminology i dont understand. Also from the link i noticed that the needles in those pictures are on a different way than mine. Does that mean mine are on wrong/backward? Or does it not make a difference? Thanks I will take the carbs out and see what's going on right after I do what Buddha suggested and recheck float heights with the tube method.
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Quote from: mr72 on February 10, 2017, 07:17:01 AM
You don't have to use calipers for this. You can actually use a 15mm bolt head as a measurement guide.
Are any of the bolt heads from this bike 15mm?
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Went and corrected float heights. Put everything together and now i have fuel coming out of this little gap(https://uploads.tapatalk-cdn.com/20170211/5ae156e9e3a5b308294a18975dfaa3e3.jpg)
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(http://imagizer.imageshack.us/v2/800x600q90/922/TEKLqx.jpg) (https://imageshack.com/i/pmTEKLqxj)
The orange line indicates the gap between the crank-case and the clutch actuator/front sprocket cover. Fuel doesn't come out of there, and neither does oil.
The red line indicates the seam of an engine cover, specifically the stator. Fuel doesn't come out of there, but oil might.
And the green X marks the starter cover. No fluids at all behind that cover, just a starter...
Nothing in that image would be the source of a fuel leak aside from the big green fuel line on the left side of the image.
If the carbs are leaking somewhere it may be dripping down onto this area?
The green (or rather yellow) is the line from my fuel tank to the pet chicken. I had overflow of fuel from the upper t on the carbs. If that may cause it. But every time i press the starter button it seems like it's lightly spitting out from where the red line and the orange line meet.
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Quote from: newbie1993 on February 11, 2017, 08:39:59 PM
The green (or rather yellow) is the line from my fuel tank to the pet chicken. I had overflow of fuel from the upper t on the carbs. If that may cause it. But every time i press the starter button it seems like it's lightly spitting out from where the red line and the orange line meet.
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That upper T is air equalization and gas escape when if you dump the bike.
Your floats are still stuck ... that's about the only way you can spit fuel out of that T, unless gravity is acting upwards in your garage.
Cool.
Buddha.
There's a couple of o'rings in the float chamber that need replacing over time: 1 is at the float needle seat. It holds the seat in place. If it's leaking you'll chase your tail trying to stop high float bowl levels. The other o'ring is holding the entire float assembly in place. You'll need to pull that assembly off and replace the o'ring there. If either of these are dry or old, they will allow fuel into the float chamber regardless of what the floats are doing.
Quote from: Arpee on February 12, 2017, 02:21:10 PM
There's a couple of o'rings in the float chamber that need replacing over time: 1 is at the float needle seat. It holds the seat in place. If it's leaking you'll chase your tail trying to stop high float bowl levels. The other o'ring is holding the entire float assembly in place. You'll need to pull that assembly off and replace the o'ring there. If either of these are dry or old, they will allow fuel into the float chamber regardless of what the floats are doing.
Needle seat o ring on one side is replaced. Kinda stupid i know but it was the only one that looked worn out. However the other ones that hold the floats in place need to be replaced. definitely need replacing. Those will definitely be replaced asap
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There is gas in my oil 😑😑😑😑
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Float heights are correct still bogging down and Im pretty sure theres fuel in my oil and oil in my fuel(https://uploads.tapatalk-cdn.com/20170216/d7e098c7ff7f6b5a53b9acfa5e8121e2.jpg)(https://uploads.tapatalk-cdn.com/20170216/566753094f7f514becfa0108e7d353ad.jpg)
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Oil in the fuel, not likely.
Fuel in the oil, most definitely. Overflowing into the airbox is often mirrored by overflowing into the engine. Liquid fuel entering the cylinders and bypass the piston rings and enter the crankcase.
With all this mess one of us should have cued in and mentioned for you to check, sorry.
The engine will not run right with gas diluted oil and may cause a potentially dangerous situation.
So long as your floats are set right (looks pretty good to me) go ahead and change the oil and filter and we'll go from there.
No worries on the cueing in. I know i ask a lot of questions. The only sad thing is that i literally just added brand new oil and a brand new oil filter. What made me realize i had fuel in my oil is after the bike would start it would run and die and then a pool of muddy looking fuel would pour out of the airbox drain hose. Would fuel in the oil mimic incorrect float heights as far as bogging down and popping from the airbox/air filter area and exhaust?
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Fuel in the oil can cause excess crankcase pressure and there's a breather that connects from the valve cover to the airbox. That could be causing the "muddy fuel" you described.
Fuel diluted oil can cause rough idle and starting issues.
The only bike that I personally know gets fuel in the oil often is another Suzuki the DRZ400 ( particularly the SM model).
Had it happen twice before I found the culprit ( online forum).
In THAT bike the seat of the fuel needle/seat control valve has an O ring around the outside that shrinks and no longer seals the OUTSIDE of it so the fuel flows straight around the outside.
Now, despite the number of times I have had the GS500 carbs off , I can't remember if it has the same push in O ring seal setup on the needle and seat. If it does That may be the culprit.
The DRZ has similiar CVcv carbs to the GS.
The bike took a little while to start but when it did start it took a little throttle to get it started. Idled high and Revved a couple times but then she bogged down and died and then "muddy fuel" poured out of the airbox drain hose. This is just me describing the situation a little more so I make sure Im taking steps in the right direction to get everything fixed. Will be picking up new oil and a new oil filter tomorrow and give an update after I see how everything goes after that.
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If you are still trying to tinker with fuel diluted oil you are doing more harm than good.
Stop doing anything until you change the oil.
All manner of bad things can happen when the oil is no longer lubricating and when you have a combustible in the crankcase.
UPDATE.
Oil and filter replaced both brand new.
Steady idle at 1.2k rpm. Easy startup after Oil change. No bogging down while giving throttle. Everything seems to be alright. Will update after test ride.
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Not sure if this is a natural occurrence but there is like no acceleration past about 1/2 throttle. If I keep it around 1/2 throttle Everything seems to be fine. Also having issues going up hills unless I play with the clutch. Also i don't know if it was the cold weather but the bike died about 3 times during a 24 mile drive. But started right back up and everything was seemingly fine.
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I haven't had any problems going up hills, provided I'm in a lower gear. What issues are you having, specifically?
As for the acceleration past 1/2 throttle, when you give the bike more throttle, do the Engine RPMs continue to rise, but you just don't seem to be going faster? If that's the case, maybe your clutch is not adjusted properly and is slipping at high RPMs?
Acceleration is perfect at half throttle and less. Any more than that there is literally no more acceleration in higher gears at highway speeds. I have to down shift to lower gears. Does just fine downhill perfect even but when i wanna go full throttle i cant. Its like the bike wants to but cant so it coughs kinda or light backfires. Clutch operates and responds perfectly it seems to be throttle response itself. Maybe mixture screws need to be adjusted or throttle cable needs to be adjusted because the throttle has a bit of freeplay
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Throttle should have a bit of freeplay and the mixture screws only handle idle speed, not open throttle.
Throttle half open is about where the main jets come in. Either these are clogged or your slides aren't working.
You can visually check this with the airbox off and revving the engine.
If the slides aren't moving you likely have a puncture in the membrane.
Main jet is the bigger of the 2 correct? And by membrane you mean the diaphragm? I submerged both diaphragms in water and saw no bubbles. Thats what I'll check. A little more information though. The bike wants to go. At anymore than 1/2 throttle it kinda surges with acceleration. Its like no power and then a lot of power and the back to nothing. And back and forth until i back off the throttle and then its back to normal.
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Sorry you're having such a hard time with the carbs. I have to admit to these carbs being particularly finicky. :icon_sad:
It sounds like you have a starvation issue now either with air or fuel. Either the plastic slides aren't lifting enough when you open the throttle (vacuum problem) or you're not getting enough fuel into the mixture, i.e. the needle isn't placed in the slide properly so could perhaps be not rising high enough. Just to be sure, I'd double/triple check you've put the needles back in the correct way, not missing any of the parts, etc.
The carbs are definitely an acquired taste.
Sounds to me like float level is low, float needle valve getting stuck closed, etc. I would just replace the o-rings and clean the carbs thoroughly, make sure you have the vacuum port caps on and the o-ring under the vacuum ports on the tops is there and in good shape, then as long as the float needle valves work and the float level is right then you should have a running bike.
The thing about these carbs is there really is not a lot of tuning. They kind of do what they do. Put stock or +1 sized jets in and as long as everything is clean and all rubber parts are intact then the ONLY thing to tune is the idle mixture and speed. Get the idle mixture screw at 2.5 turns out and the bike should start and run fine and you might be able to dial it in a tiny bit better but overall basically that's all there is to it. Anything causing it to not run right is not because of carbs being out of tune, it's because of degraded parts in the carbs somewhere causing either a vacuum leak, a fuel leak (bad o-rings), or something is clogged (tiny little orifices).
Quote from: mr72 on February 24, 2017, 09:27:47 AM
The carbs are definitely an acquired taste.
Sounds to me like float level is low, float needle valve getting stuck closed, etc. I would just replace the o-rings and clean the carbs thoroughly, make sure you have the vacuum port caps on and the o-ring under the vacuum ports on the tops is there and in good shape, then as long as the float needle valves work and the float level is right then you should have a running bike.
The thing about these carbs is there really is not a lot of tuning. They kind of do what they do. Put stock or +1 sized jets in and as long as everything is clean and all rubber parts are intact then the ONLY thing to tune is the idle mixture and speed. Get the idle mixture screw at 2.5 turns out and the bike should start and run fine and you might be able to dial it in a tiny bit better but overall basically that's all there is to it. Anything causing it to not run right is not because of carbs being out of tune, it's because of degraded parts in the carbs somewhere causing either a vacuum leak, a fuel leak (bad o-rings), or something is clogged (tiny little orifices).
You guys are awesome. My right side carb float level is low. I figured i would have with running a little lean than a lot rich. I didnt know it would take my throttle away from me. Now i know. The level is about 4-5mm below where the carb bowl meets the carb body.
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I think you've done well to keep troubleshooting and working at it. I'm sure a lot of people would have just cut their losses and outsourced the job. Good for you :cheers:
Chris
O0
I went and reset the right carb now its about 2-4mm above where it should be. The issue is a little better but still having problems with surges in power. Downhill I've got no issues which i expected. But uphill and sometimes on level planes its hard to maintain speed or even gain. Would a little rust from the tank cause this or possibly make this issue worse? I noticed a little rust when i drained the float bowl to reset the float height.
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Also the float height is about 2mm below where it should be after rechecking heights.
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downhill/uphill differences probably either float height or o-ring leak in the carb.
O-ring leak where though? And my height on the left is perfect. On the right its about 2mm below where it should be. I dont lose speed uphill i just dont gain any unless i already have a good bit of speed in which case i continue to gain speed.
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Quote from: newbie1993 on March 02, 2017, 03:39:20 PM
O-ring leak where though?
Who cares? On an '89-00 GS (IDK what year yours is) there are four o-rings on each carb that warrant replacing: float, float needle seat, idle mixture needle o-ring and the "little o-ring" on the vacuum port under the top of the carb. Add to that the intake boot o-rings and that makes a round 10 o-rings total that you should replace. Just replace them all and then quit worrying about o-rings. It's almost exactly the same amount of work to replace all of them as it is to replace one and then you don't have to try and figure out which of the dried-up worn-out o-rings is the one that's leaking the most.
While you have that apart replacing the o-rings you can examine the diaphragm under the top and make sure it has not been destroyed by carb cleaner or age. While the carbs are on the bench it's easy to lift the slides and make sure they return smoothly. You can make sure the main needle is not misaligned with the main jet so it hangs up and prevents the slide from closing (it happened to me!). And you can properly set the float level once and for all. Win-win. Takes two hours or less even for a beginner to do all of this with $10 worth of parts.
"there are four o-rings on each carb that warrant replacing: float, float needle seat, idle mixture needle o-ring and the "little o-ring" on the vacuum port under the top of the carb."
Im ordering parts and im not sure which one is the idle mixture needle oring.
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