Hey everyone...I hope someone can help me with this. I bought my bike early this year, and especially as I start riding a little more aggressively I've noticed an issue that I cannot pinpoint the cause. When I'm accelerating, especially hard acceleration in 4th-6th gears, I lose power between 5000-6000 RPM. Initially, I thought that this was the clutch slipping, but the more I ride, and the more I think about it, I'm not seeing an RPM spike when this happens...it's more like I'm hitting a rev limiter and neither the engine nor the bike will go any faster. I've found that sometimes if I let off the throttle and get back on it, that solves the issue (another reason that I thought it was the clutch). I'm thinking that maybe it's a carburetor/fueling issue. When I first bought the bike I had to replace one of the carb floats because it had a pinhole leak and was filling with fuel...perhaps I didn't adjust the float height correctly...could this be causing my issue? Or does anyone have any other ideas? Any input is greatly appreciated...I need to get this fixed ASAP.
A guy on another forum had a similar issue with his bike, and it turned out to be dirty carbs. Since I had mine apart when I replaced the leaky carb float, and they looked pretty immaculate, I don't think that's my problem. I suppose it could still be an issue with float height, but I've not had an opportunity to check it yet. Any other ideas???
http://forum.motorcycle-usa.com/default.aspx?f=18&m=497849
Could it be that one of your jet needles/slides isn't opening all the way? Curious if you figured this out.
Quote from: smokestack on July 16, 2016, 12:38:49 AM
Could it be that one of your jet needles/slides isn't opening all the way? Curious if you figured this out.
I had a sick kid over the weekend, so I didn't get a chance to pull the carbs apart. I'll hopefully get around to it sometime this week.
Update...sort of.
I rode to my brother's house last weekend so I'd have an extra pair of hands to help with this stuff. We adjusted the float levels...one was about 1.5mm off, but the adjustment failed to solve my problem. By the time we put the bike back together, not only was it dark, but the work light we were using burned out. Long story short, I got it home and took another look (since it still wasn't running right), and I put the float bowls on backwards and we missed one of the hoses when we were reconnecting everything.
It's back on the center stand now (it's been sitting there since last weekend, while I haven't had time to work on it), and I'm setting aside some time this weekend to get it fixed. I just really don't even know where to start at this point, aside from fixing my stupid reassembly mistakes. I know my earlier explanation wasn't all that clear, so here's what I've got going on...as I'm accelerating, when I get to around 55-60 MPH the bike acts as though it doesn't have any more to give. It sounds almost like it's hitting a rev limiter, and even if I'm giving it full throttle it doesn't want to go anymore. After a few seconds of this, sometimes it will lurch forward and continue accelerating...other times it doesn't - which is probably a result of my throttle input, but I haven't experimented quite enough to pinpoint it.
Pretty frustrating, because this is where I feel like I should be getting the greatest amount of power out of the bike, but there's nothing. It's especially scary when I'm trying to pass someone...
Any ideas? Other than cleaning the carbs, I'm not sure what else to even consider as a starting point.
Insufficient fuel flow..... next time it does it, do a plug chop. I'd bet your spark plugs are white from being lean at that range.
Search for fuel starvation, and you'll find all the possibilities. I can't remember - have you messed with the jets? If you accidentally put in smaller mains instead of larger ones, that could do it too.
Thanks Rich. I haven't messed with the jets, but perhaps they're clogged? I'll take the plugs out and look at them later today. Have to go get passports for the kids this morning, but I should have most of the afternoon to tinker.
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How's the air filter? Correct part for the bike?
It's clean, and as far as I know it's OEM.
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post the part number
Quote from: rscottlow on August 13, 2016, 05:55:33 AM
Thanks Rich. I haven't messed with the jets, but perhaps they're clogged? I'll take the plugs out and look at them later today. Have to go get passports for the kids this morning, but I should have most of the afternoon to tinker.
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While it is possible your main jets are clogged, that's probably not the problem. I say that because the pilot jets become clogged much more easily than the mains (smaller holes). So if it's running well off idle and thru the midrange, I think you're running out of gas when the engine demands it.
I cleaned the jets, even though they already looked clean. I put everything back together and went down the road for a test ride. Now it's doing the same thing, but also in 2nd and 3rd gears. If it's this simple, I might just kick myself, but is it possible that too much slack in the throttle cable is causing this? It looked a little loose, but visually appeared to be operating correctly so I didn't worry about it. I didn't do any intentional adjustment any of the roughly half a dozen times I've taken the carbs out, and it seems as though it would be easy to accidentally loosen or tighten the cables when removing and reattaching them. But could that cause me to be losing power only at higher RPM range? When it's sitting in neutral, I can rev it up just fine, but would being under load make a difference?
Sorry for my lack of knowledge, but this is my first bike, and I've never worked on a small motor before I bought this thing.
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Quote from: HPP8140 on August 13, 2016, 04:00:20 PM
post the part number
It's dark and raining now, but I'll look tomorrow. I assume based on the symptoms worsening, though, that it must be related to something that I've done.
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I made some adjustments to the throttle cables. If nothing else, it started up easier, and is idling better than it was. It's raining here, so I can't go test it out, but as soon as it dries up, I'll report back.
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Took it out, and the issue is not resolved. Same thing as before, but I rode it around a while longer since it was only raining a little bit, and I was trying to collect as much information as possible. So here's what I have: when I open the throttle all the way, the bike doesn't run well at all. I mean to the point where if I'm going up hill and I open it up, RPMs will actually drop. Partially closed, I can get enough power to make my way up a hill, but very slowly. Going downhill, the bike almost operates as normal. If I really get into it, I can still hear and feel the loss of power when I open it up, though. Again, my knowledge is really limited, but doesn't this point to fuel mixture? Something in the carbs? I just don't know why it got worse after I cleaned the jets, unless I messed something else up while I was in there...
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Other things I noticed...once I get it up past where power initially drops off (usually by letting off the throttle some), I can keep accelerating...but only to a certain point. For example, I couldn't get it above 10,000 RPM in first, 8,000 in second.
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Hope you've figured out the issue, but I'm curious - I don't know much about this area, but it does seem like a mixture issue, I'd assume that it is only tied to the RPMs and in that case the issue could be emulated without riding - just revving up the bike? Did your bike have the same issue w/choke on ? I wonder if fuel lines are clogged or if there are gremlins on the vac side - although I guess those show themselves even at idle...
Quote from: AK Baller on August 24, 2016, 11:27:52 PM
Hope you've figured out the issue, but I'm curious - I don't know much about this area, but it does seem like a mixture issue, I'd assume that it is only tied to the RPMs and in that case the issue could be emulated without riding - just revving up the bike? Did your bike have the same issue w/choke on ? I wonder if fuel lines are clogged or if there are gremlins on the vac side - although I guess those show themselves even at idle...
Unfortunately, I haven't figured it out yet. I'm sure it's simple, but I haven't found time to work on it much. I agree it sounds like a mixture issue, but the issue cannot be replicated by just revving up the bike. I even put it on the center stand and went through the gears to see if I could recreate the problem, but no luck. So this is only happening under load at higher RPM's. Based on what I've read, this points me right back to the carbs, but all I know is what I've read online.
So just to recap...I replaced one of the floats early this riding season due to a pinhole leak causing it to fill with fuel and not float. When I installed the new one, I don't think I adjusted the float level properly, which caused my initial problem - bogging down in higher gears at higher RPM's. A few weeks back, I pulled the carbs out and adjusted the float height correctly, but ran out of daylight and my work light burned out while the bike was still apart (I was at my brother's house, and my bike was my ride home so I had to get it put back together). We finished reassembly with flashlights, but put the float bowls on backwards and missed a couple of hoses when putting the carbs back on. It rode somewhat poorly on the way home - part of this was due to my brother fiddling with the idle screw when the bike didn't seem to start up just right. The next day, I pulled the carbs back out, flipped the float bowls, put everything back together (I think correctly), and took it out for a quick test ride. This is when it started bogging down in second and third. My only remaining hypothesis is that when I was switching the float bowls around, I think I pushed down on the floats when I was examining them to make sure the needles were seated correctly and whatnot - perhaps I pushed too hard, bending the tabs, and throwing off that adjustment. Sometime within the next few days I'm hoping to get the carbs back out and measure the float height (or use the clear tube method if I can find some clear tubing that is the correct size...any suggestions on where to find this stuff? I've tried a couple different sizes, but none that fit snugly on the drain holes). If it's not the float height, then I honestly don't even know what to check next. I'll hopefully report back with a fixed GS sometime this weekend...then again, Oktoberfest is this weekend, so who knows when I'll find time :dunno_black:
This is mostly for my reference, but this may have something to do with my issues...so many hoses. I marked them when I initially took the carbs apart, but not very well, and much of the paint has come off since I first took the carbs out.
http://gstwins.com/gsboard/index.php?topic=56491.0 (http://gstwins.com/gsboard/index.php?topic=56491.0)
Have you already ruled out a slipping clutch?
Has someone (previous owner) gone messing with the mixture screws? It might help to remove those and make sure that one of the tips hasn't broken off. Someone will need to help me out with the exact factory setting, but I believe it's 3.5 turns from closed.
Have you ruled out ignition issues? I had a bike that acted similarly - turns out that it was a fault in the spark plug boot allowing it to arc at higher RPM.
Methinks slippy clutch.
From the original post:
Initially, I thought that this was the clutch slipping, but the more I ride, and the more I think about it, I'm not seeing an RPM spike when this happens...
(End quote)
So it's not looking like a slipping clutch guys.
Quote from: smokestack on August 28, 2016, 08:23:58 PM
Methinks slippy clutch.
Yep...that was my original thought too. It's worsened considerably, as I've pulled out the carbs, made adjustments, and reassembled. So that makes me think it has to be related to the fuel mixture. I checked the float heights again - one was off a little bit, probably from me fiddling with it so many times. I readjusted it to 13mm, and now it's bogging down all over the place. I've tried messing with the choke while riding - that doesn't seem to have much of an effect.
So...originally, it was only bogging down during hard acceleration in higher gears. I adjusted the floats, but did not reconnect all of the vacuum hoses correctly. Since it didn't seem to be running right, I adjusted the idle screw and was able to ride home. Next, when I took the tank back off to fix the vacuum hoses, I also cleaned the jets - they seemed clean already, but I thought it wouldn't hurt to soak them in carb cleaner. Upon reassembly (and the vacuum hoses being hooked up correctly), it started bogging down in lower gears at high RPM as well. I readjusted the idle screw. Took the carbs apart once more, and did my most recent float height adjustment, and now it's bogging down everywhere. So I'm back to square one, but it's currently worse than it has been since I started. Since it got worse after working on it, I feel like it has to be something that I did wrong, but at this point, I'm clueless as to what that might be. That's why I keep going back to float height...that's pretty much the only thing I've touched...
Quote from: Kijona on August 28, 2016, 08:19:46 PM
Has someone (previous owner) gone messing with the mixture screws? It might help to remove those and make sure that one of the tips hasn't broken off. Someone will need to help me out with the exact factory setting, but I believe it's 3.5 turns from closed.
Have you ruled out ignition issues? I had a bike that acted similarly - turns out that it was a fault in the spark plug boot allowing it to arc at higher RPM.
I don't know much about what the PO did with this bike. I know it had been down prior to my purchase (PO claimed it happened before he bought it). It's got aftermarket mirrors, signals, passenger pegs, and bar ends (all an obvious result of being dropped). The signals were never wired correctly, so whoever did the replacement clearly did not know what they were doing with it. I bought the bike very early this spring (late Feb, early March), and it had been properly winterized by the PO or his mechanic. After I bought it, I had an issue where the bike was not fueling properly - it turned out to be a leak in one of the carb floats, which I replaced. I also ended up replacing the signal generator after the bike mysteriously stopped getting a spark. Since then, I had no issues with it until I started riding harder and noticed it bogging down in higher gears.
I'll check on the mixture screws - it's possible that the PO could have messed with them to compensate for the one float not floating due to the leak? And after I replaced the float, I guess that could have caused the issue to become more apparent. When I originally put the new float in, I think I forgot to adjust the float height. So then, when I corrected the float height, that could have caused the issue to worsen and become noticeable in lower gears? - So I guess my next question is, where are the mixture screws? (I have a manual at home, so I can look later...).
I have not yet ruled out any ignition issues - everything thus far has pointed towards fueling, so that's all I've investigated yet.
That dropping rpm with increasing load - 10k in first, 8k in 2nd, 6k in 3rd, 4k in 4th etc etc - are likely the result of a diaphragm with a tiny rip.
You could also have a plain jetting issue.
Definitely not slipping clutch, with a slipping clutch you rev out like you're in neutral, but not get any faster. You'd in fact get slower with increasing revs.
If you're doing 40 @ 4k and you clutch is slipping, usually it will slip on acceleration, you'd be doing 6k but be only going 30 in the same gear.
Cool.
Buddha.
Quote from: The Buddha on August 29, 2016, 07:12:18 AM
That dropping rpm with increasing load - 10k in first, 8k in 2nd, 6k in 3rd, 4k in 4th etc etc - are likely the result of a diaphragm with a tiny rip.
You could also have a plain jetting issue.
Definitely not slipping clutch, with a slipping clutch you rev out like you're in neutral, but not get any faster. You'd in fact get slower with increasing revs.
If you're doing 40 @ 4k and you clutch is slipping, usually it will slip on acceleration, you'd be doing 6k but be only going 30 in the same gear.
Cool.
Buddha.
Your sentiment about the clutch makes total sense to me - I jumped to that conclusion when the problem started, but after I rode a couple more times I realized that couldn't be the case.
Jets are all stock sizes - I pulled them out and soaked them in carb cleaner for a couple of hours, then sprayed some carb cleaner through them just to make sure they were clean.
Where is the diaphragm located? I haven't taken the tops of the carbs apart at all - I don't have the tools or the know-how to re-sync the carbs, so I've avoided messing with anything that I'm afraid could do more harm than good...
The problem worsened after disassembly and reassembly, and even after checking several times, I'm sure that all has been put back together as it should - so perhaps this is the wrong assumption, but I feel like something I did made the problem worse. I just don't know what it could be.
Bumping to be able to find this thread again.
I just bought my GS500E '08 last week and I'm having the exact same problem of not gaining extra power at 6K+ RPM.
Although for me it's like this in every gear, time to learn how to clean carbs..
Diaphragm is at the top. Just remove 2 screws to remove black cap.
Quote from: HPP8140 on August 29, 2016, 09:11:14 AM
Diaphragm is at the top. Just remove 2 screws to remove black cap.
Thanks, sounds like it'll be easy to check this one out...I'll hopefully be able to report back this evening.
Misassembly of the diaphragm can cause this too. And the diaphragm getting a little damage from a bad assembly job also is possible.
Cool.
Buddha.
Quote from: The Buddha on August 29, 2016, 12:02:41 PM
Misassembly of the diaphragm can cause this too. And the diaphragm getting a little damage from a bad assembly job also is possible.
Cool.
Buddha.
I'll look into it...I haven't had the top of the carbs apart yet, so if this is the case, it would have to have been done prior to me purchasing the bike 6 months ago. I suppose it's possible that the PO made adjustments to compensate for the bike running poorly, so in correcting the float height adjustments to spec, the problem is getting worse for me?
I think I may have found the problem (thanks Buddha!). I finally got around to checking the diaphragm, and this is what I found. I haven't checked the other side yet (my wife is out shopping this morning, and I have the kids), but I was too excited when I found this, not to share right away. Once my wife gets home, I'll get this thing out for a test ride, and hopefully be good to go.
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Update: took a closer look, and whoever installed it had it pinched under the cover. I won't be able to get it seated properly, so I'm going to order a replacement. Any suggestions? Partzilla? Or is there a better/cheaper option?
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Another update: I managed to get the existing diaphragm seated on there properly. There are still creases where it was punched under the cover, but I looked pretty closely and didn't see any tears or holes. I've got it all back together...just waiting for my wife to get home so I can test it out. It should at least be running better than it was.
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And...one more update for today. Got out for a quick test ride. It's much improved, but still running overall sluggishly. It takes off slow in first, and if I'm taking off on an incline, it has a lot of difficulty getting up the hill. Once I hit 5500, power improves significantly. I can go through the gears keeping it at higher RPMs and it rides okay. Just slower than it should. Am I to assume that since its creased on the edge, the diaphragm is not sealing? I'm on the verge of ordering a replacement, I was just hoping to be able to ride until it arrives.
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This is sort of the opposite of the problem you had before, no? Now it runs fine at >5k rpm but is iffy at lower revs?
I am far from an expert (just read my other rambling posts trying to get my bike to basically run right) but it still sounds to me like maybe it's running lean on pilot. Maybe you just need to adjust the idle mix needles a bit and it will improve. You might try riding it with a little bit of choke on and see if the lower rpm hesitation or lack of power improves at the low revs. If so that might point to a lean idle/pilot mixture.
Did you check out the fuel flow to the carbs? If the flow from the tank is restricted (most likely a clogged petcock or two) then you will not have sufficient fuel flow to the carb bowls. The bike might run and idle and rev up fine for the first few minutes, but then starve for fuel after a short ride.
Ive ridden many machines around my property, only to discover that the petcock was turned off the whole time. You would be surprised how far a bike will go on the bowl alone.
However, I have to add my standard question; when was the last time you checked the valves?
Quote from: mr72 on September 04, 2016, 04:28:27 AM
This is sort of the opposite of the problem you had before, no? Now it runs fine at >5k rpm but is iffy at lower revs?
I am far from an expert (just read my other rambling posts trying to get my bike to basically run right) but it still sounds to me like maybe it's running lean on pilot. Maybe you just need to adjust the idle mix needles a bit and it will improve. You might try riding it with a little bit of choke on and see if the lower rpm hesitation or lack of power improves at the low revs. If so that might point to a lean idle/pilot mixture.
Haha, I hear you. I've been following your progress with much empathy. Yeah, it basically is the opposite of what it was doing before. I'll see how it runs with the choke on tomorrow hopefully. Then I'll check the idle screws and probably reset them to spec and see what happens.
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Quote from: W201028 on September 04, 2016, 07:47:46 AM
Did you check out the fuel flow to the carbs? If the flow from the tank is restricted (most likely a clogged petcock or two) then you will not have sufficient fuel flow to the carb bowls. The bike might run and idle and rev up fine for the first few minutes, but then starve for fuel after a short ride.
Ive ridden many machines around my property, only to discover that the petcock was turned off the whole time. You would be surprised how far a bike will go on the bowl alone.
However, I have to add my standard question; when was the last time you checked the valves?
I haven't checked the valves. Until this point the bike appeared very well maintained. The PO said he was told the valve stem seals were bad, but I don't know how much that would affect how it runs. This is my first bike, and I just got it in the spring.
I can look into fuel supply if the idle adjustment makes a difference. I'm also still considering that the diaphragm may be leaking air, but I don't know if the way it's running now supports that hypothesis.
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Quote from: rscottlow on September 04, 2016, 05:12:35 PM
Haha, I hear you. I've been following your progress with much empathy.
I only wish my problem was as simple as yours :)
Quote
Yeah, it basically is the opposite of what it was doing before.
I think that means: you fixed it!
And now you might have a new problem that is probably much easier to fix.
Quote from: mr72 on September 05, 2016, 04:41:39 AM
I think that means: you fixed it!
And now you might have a new problem that is probably much easier to fix.
I sure hope so lol. This one was a pretty easy fix...I just didn't know what to look for, so it took a long time for me to find the problem. I didn't get a chance to tinker anymore over the weekend, but I was out at my great uncle's house setting up tree stands yesterday--he's retired, and is always looking for something to tinker with--and he mentioned that if I can't get it running right before I put it away for the winter, to bring the carbs out to him and he'll play with them. Worst case scenario, of course, but at least it's another option to fall back on. That being said, I really hope I can get it running properly before I have to put it away for the winter.
Quote from: rscottlow on August 14, 2016, 04:05:29 PM
Other things I noticed...once I get it up past where power initially drops off (usually by letting off the throttle some), I can keep accelerating...but only to a certain point. For example, I couldn't get it above 10,000 RPM in first, 8,000 in second.
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FWIW, I just took mine to NC and TN after doing a full cleaning on the carbs (the bike sat in weather for ~3 years before I got it - the carbs were a mess inside). I have basically the exact same issues that are mild at sea level (I live in Delaware, our biggest hill is about 300 feet LOL) and severely exacerbated, to the point of "oh shaZam! I'm gonna die" at ~5,000 feet elevation.
I can't find anything else wrong anywhere. (I work IT these days, but my first career was in auto- and motorcycle-mechanics)
Bottom line: Jet kit ordered, and in your case I'd do the same (with a full needle kit and perhaps slide drill).
Note: my previous response was before seeing you found an issue with the diaphragm.
When in doubt, back to basics. These bikes are basically 80s and 90s tech parts bin bikes, which means they come out of the factory running lean as all heck, rather than using modern fuel systems, to make the EPA happy.
Replace the diaphragm - it doesn't take much to damage them to the point of not working correctly, then get a decent stage-1 kit with needles, and follow the directions for stock airflow (filter and muffler - assuming they're stock).
If you suspect the carbs' cleanliness before doing the kit, FULLY disassemble them (don't be too intimidated and take pictures along the way), then soak the bodies in a can of this stuff for a few hours, rinse with water and blow them out with compressed air, making sure to shove lots of air in every single hole, orifice, etc. (wear safety glasses)
If that doesn't do it, you have another issue, and yes, it's *always* a good idea to thoroughly check the rest of the fuel system - ensure flow, that the petcock isn't hung up, the fuel pickup tube is clean-n-clear, etc.
Parts cleaner mentioned above (generally available at most auto parts stores, too):
https://www.amazon.com/Berryman-0996-Chem-Dip-Carburetor-Cleaner/dp/B00DSMEL2A
(https://images-na.ssl-images-amazon.com/images/I/41YpPfMm49L.jpg)
Finally ordered the replacement diaphragm this morning. I'm crossing my fingers until it arrives, in hopes that all of my problems will disappear upon installation...
So...you want to talk about checking the simple things first? To make a long story short, I think I've fixed it...
Somewhere along this painful journey of not being able to ride my GS, I pulled the right spark plug to try to determine whether it was running rich or lean. When I did, I was being lazy, and only took a couple of the right side fairing screws out and kind of held the fairing out of the way instead of taking it all the way off. When I put the plug back in, I must not have reconnected the spark plug wire. :dunno_black:
When I re-seated the diaphragm, the carbs issue was resolved, but it was still running all around sluggishly. I ordered the new diaphragm in case the old one still wasn't sealing correctly, and I installed it this morning. I took it out for a test ride, and it was hardly improved. I decided to check the plugs again, so this time I removed the right side fairing. Lo and behold, I've been running on one cylinder. So I feel like a total dummy, but I reconnected the spark plug, started it up (to a much healthier sound...I don't know how I didn't notice it before), and let it run for 20 minutes or so to clear out that right cylinder. I reset the idle, and it seems to be running fine. I'm working from home today, and I get off in 15 minutes so I'll take it out for a ride to see how it's running under load. I don't want to jinx it, but I think my problem has been solved :woohoo:
Hahaha I'm a dummy. But it's fixed, and that makes me happy lol.
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Great to hear you fixed your problem! Ride safe mate.
I would've never said "connect the spark plug boots"..... haha.
Glad to hear you're all fixed up!