So I finally got my bike back together and tried it out last weekend, but I was having the same problems with hanging idle like plenty of people do. I messed with it a while yesterday morning, and pretty much soaked the thing in WD40 before determining that I can't find an air leak anywhere. I pulled my carbs anyway because some gas is drilling from them somewhere, so I'm just going to try to rebuild them, but do you have any good places to start that might be causing this? I don't mind trying these out, but the P.O. installed that god awful loud V&H full system, and I live in the city, so I try to keep the bike running/revving as little as possible when I'm outside my house working on it. Sitting outside revving the engine really isn't my goal as far as staying on the neighbors good side. I guess I'll pull the black caps off the top and inspect that some, I've been wondering if there's a part inside the carb that might stick, keeping the airflow a little longer after I let off the throttle?
Sorry for the repeat question, I know it's been covered so many times, but the answer always seems to be an air leak, and mine could be, but I can't find one!
I'd be curious to see if you find a solution to this. I've been fighting the same freaking problem for the past month. Bike jumps straight to 6K on start. Sprayed everything with WD40, no effect. Just finished checking valve clearances, float heights are good, got the little o ring at the top of the carb, no sticking cables; all the usual suspects.
I have the tank off the bike when I'm running it so I can mess with everything while its revving like crazy. If I hold my hand over the air filter and restrict the flow, I can get the bike to idle down to 2K, but as soon as I let my hand off, jumps straight back up.
Everything is stock in my case, however awaiting a Buddha jet kit to try and richen her up (don't know if it will help).
Just to check, have you messed with the air/fuel mixture screws? Personally, I've tried everything from 1 turn out to 5 with no significant changes...
Don't know what they are called in English, but on the carbs, find the rubber caps that you need to remove when you sync the carbs. When you remove these caps your idle will go crazy.
I forgot to put the caps back on when I synced my carb, and I just could'nt get a stable idle. I messed around with this for almost a week before I found out the caps were missing :icon_rolleyes: .
If they are not missing, then check that they are not fractured.
The little caps that you're talking about, are they the ones on top of the carbs? I have both of those on. I haven't messed with the mix screws. Everyone always says not to touch them, and the bike ran before with them set how they were. I'm just going to try rebuilding them and hope whatever I messed up last time doesn't happen again.
Idle can hang with lean mix. This is the biggest cause of the problem.
It also can hang wiht a tight valve or a exhaust leak, neither of which will respond to the wd40 trick.
Cool.
Buddha.
Hmm... I know all of my valves are tight, but the buckets still spin, so they're not ridiculously tight. I did remove the exhaust to repaint it and replace the exhaust gaskets though, so I'll check and make sure that's on tight. To be honest with you guys, I'm not that crazy about engines.... haha
Quote from: tt_four on March 21, 2010, 04:45:33 PM
I haven't messed with the mix screws. Everyone always says not to touch them...
Everyone lies. Touch them.
The idle mixture is wrong from the factory. Once you add some mods, it's really wrong. They're screws for a reason. That reason is so you can adjust them.
The brass plugs are no longer there, so the previous owner definitely messed with them at some point, but I don't really trust his work. Is there a certain method to it? Do I screw them all the way in the slowly back them out until it seems to run right, or screw them out and then slowly start screwing them in?
All the way in, then out as many turns as needed.
Quote from: tt_four on March 21, 2010, 07:26:54 PM
Hmm... I know all of my valves are tight, but the buckets still spin, so they're not ridiculously tight. I did remove the exhaust to repaint it and replace the exhaust gaskets though, so I'll check and make sure that's on tight. To be honest with you guys, I'm not that crazy about engines.... haha
OK this is the standard buddha trap. There is a potential situation where it is loose enough to spin when cold, and yet tight enough to hang open when warming up but fine when fully warmed up. Think about it. The valve is steel. So is the cam shaft bucket and shim. The head is aluminum which expands almost 2X ... however the head dissipates heat so well, being the only part of these 3 with a live air feed and direct oil puddling.
I'd seriously set em back into the measurable range.
Then ... rejet ... I dunno who says never to touch the air screws ... and we always set it to 3 as a start, not a set in stone number. We also swap pilots ... and mains ... and set the floats and needles.
Cool.
Buddha.
When you say you set them to 3, do you mean screw them all the way in, then back them out 3 full turns?
I definitely plan on readjusting my valves, I was just hoping to get my bike running so I could ride it to a dealership to get the new shims. I don't really have much 'outside the city' transportation, which is normally fine, but there's no bike shops inside the city either.
The thing that bugs me is that it ran fine before, so I feel like it's something I did wrong putting it back together. It's not like your bike runs ok, you pull it apart, and put it back together and all of a sudden the valves are too far out of adjustment to run properly. First thing I'm going to do is clean and rebuild the carbs, and if it still doesn't run right, I'll start in on some more serious measures, and then I'll be readjusting the valves sometime soon regardless.
Screw mixture screws all the way in then 2-3 turns out and warm up,adjust to suit.Have you checked your slides and needles are returning smoothly?
mine did this after dynojet kit, k&n, and slip on cobra f1. set floats, all new o rings and float needles and seats. still hung. dynojets baseline was 2 turns out. Im at about 4.75. Carbs are synched by eyeball pretty damn welll. But im sure a proper vacuum guage would help to get the dialed it. Idles super low for me. 1000rpm somethings 9oosh for a bit. 15 minutes itll stay at its 1250. thinking i need a good synch.
I have the DJ needles in there now, which I know plenty of people consider to be junk. Would I be better off putting the stock needles back in? and if so, what about the little washers and all that? I haven't gotten to mess with it yet. I'm taking 2 days off this weekend, so I'm gonna try to get some stuff done then. I've also got that box of moped stuff that'll be showing up this week, and even though the GS is cooler, I think the moped will be a lot simpler to get running, so I'll be tempted to get working on that first just so I can at least get out and ride something. It's tough having too many projects all at the same time.
One other thing to look at while you have the carbs open. On my 97, the engine wasn't returning to idle when the bike slowed like it should have. Turned out to be the hole in the bottom of one of the carb slides being buggered up. The needle would tilt a little in the emulsion tube and not drop when the slide dropped. I ended up wearing one of the needles to the point it broke, at which point the bike ran like crap since only one cylinder was fully using the main jets. So check the condition of the slides while you have the carbs open to make sure you don't have a similar situation.
Im going nuts. This is whats happening. I rejetted, new o-rings and float needles. NO air leaks.
It will hold an idle, but not without the rpms hanging and reallly slowly coming down after i rev it. If i turn the idle screw down, the revs wont hang and will come down, but now it wont idle above 1K or will die. Ive been messing with air/fuel screws without much success. Dynojet kit...yeah i know.
So should i keep richening with mix screws until i can set the proper idle without the hanging issue? Im at 5 turns and its still doing it. Plugs look good. If anything a little lean.
Im thinking a good legit carb synch with the mercury sticks will help.
Any ideas?? input? thanks.
I haven't figured mine out yet. I plan to toy with it a little this weekend, although I'm dogsitting for my parents, so who knows how much free time I'll really have. I've actually spent more time fixing up that moped lately, because because I wanted to feel productive for once. If I get it completely back together and then have 2 vehicles that aren't running right I'm going to blow a blood vessel.
Anyway, I'm gonna mess with mine over the weekend and I'll let you know if I make any progress. If i don't I may up the pilot jet like Buddha recommended for you. My bike has the dynojet kit in it as well. No sure what's so awful about them as it's just different jets and a needle, but who knows. I've been wondering if I'd have better luck if I kept the jets but went back to my stock needles.
Well, still the same issue here. Misery loves company. I have noticed that it seems worse when the bike is fully warmed. For example, I can maintain a semi steady idle at 1200 with the choke when initially start the bike, but after about 10 minutes of running I can't get the thing under 6K RPMs without restricting the air intake. Perhaps some hole is expanding as it warms up?
Anyway, I got 125 mains and 40 pilots in yesterday, so I'm going to see how that helps. I had a dream that it helped, so who knows.... :cookoo:
Ive pretty much narrowed it down to float heights. Doing the check with the float drain and clear tubing, my level is a tad lower than the gasket level where it should be. Such a pain to do because you gotta pull the carbs, then back on, check, then if not right all over again. Erg. And nothing but good weather is on the way. So im gonna just run my idle low and rev it at stop lights to keep it going, haha! Then do float heights on a rainy weekend.
Floats can be done on the bike. Heck they can be done wiht the fuel lines still connected ... if you dont mind a little gas spilling here and there and have steady hands, you can get it spot on ... however yo uhad to have swapped out the float bowl bolts with allen head screws.
Cool.
Buddha.
Once you get the basic idea of carbs (i.e. rebuilding, cleaning, putting them back together 1000 times, etc...) it's not too difficult to start to overlook simple stuff. Things that you normally would think to yourself "no way!"
But, if your shims are close, your carbs are cleaned and set properly (turned all the way in then 3 turns out for re-jet), you are getting a spark at the plugs, and gas when you cover the intake side of the carbs with your hands while trying to start, then about the only thing left to check is the float height which should be as spot on to the the carb body / float bowl seams and / or the throttle cable where it tightens against the carb body.
I found that I could get my bike started well, get it to idle somewhat well around 1150 - 1300 then take off riding. Once I was underway, it wasn't long before I experienced really high revs when I pull the clutch or shift to neutral. One day, while I was fighting with this problem, I used a small temporary gas tanks and simply got the bike running, then, I pulled on the cable near the carbs and found that with some movement, it would cause a high / hanging rev. So, I tightened it down literally tightening the cable against the nut all the way down to the carb body. It was only then that I could not get the cable to cause the high revs and to this day, that is the way I have to set my throttle cable otherwise, I get all sorts of hanging idle problems.
i would check that area after you get your bike buttoned back up. leave the tank off or loose so you can reach the throttle cable AT the carburetor body. Then wiggle it. If you get weird accelleration / revs, that is where your problem could be.
Good luck, I nearly took a sledge hammer to my bike trying to figure this out.
Well, I finally get to share a bit of success. Started today with stock jetting and stuck at 6K RPMs when bike is warm, to now at 125 mains, 40 pilots, 1 washer, 5 turns out and a reasonably running GS! The revs still seem to slowly come down after some throttle but I was able to take it for a 20 min spin tonight around the block and ever time I pulled the clutch in, the thing dove right down to idle. I had to tweak the idle screw a bit to get the idle where I wanted once it got warm, but it idles well at stops now.
I'm not so sure about my mixture screw setting (5 turns); I started at 3 turns out and incremently went half a turn up until the revs seemed to respond the best. I think I can go in a bit; I may tweak it some more later.
I doubt I can list everything I've done to get to this point since 2 months ago, but this is the first night I've gotten positive results. New clutch cable, carb cleaning, all new o-rings, new float needles, one new float, one new needle seat, valve clearance check, new cylinder head manifold boots, new fuel lines, floats set, eyeball synch (tried the $5 synch tool, but not getting great results), sprayed WD-40/carb cleaner for vacuum leaks, frame mounted petcock vacuumless mod, lubed all cables, new battery, rejet, oil change, and probably a million other things!
I'd like to get the carbs synched better, tune in the mixture screws and need to look at my clutch cable routing (revs as I turn bars to the right), but I'm finally able to ride the thing again! :woohoo:
lowering my float height really helped my problem a ton. did it last night. revs come down nicely, idles at around 1200. maybe a hair less. still takes forever to warm up though...
Actually after riding to work this morning...same crap. Last night it seemed perfect in my garage. Then after riding about 10 miles back to crap idle and hanging revs. Rideable but annoying. Synching at my buddies garage Friday. Maybe that will help clear things up a bit.
My hanging idle issue is driving me nuts. Here is what I have done so far with little to no luck:
-Swap engines with a spare one
-3 different carbs
-new intake manifold (carb boots)
-new petpock
-net exhaust gasket
The only constant is the darn airbox. Could a leaky airbox cause a hanging idle problem?
Check that the bolts at the downpipes are tight, and that there is no leaking there.
Quote from: bombjack on April 11, 2010, 03:19:21 AM
Check that the bolts at the downpipes are tight, and that there is no leaking there.
I did that. I even tried tightening them again when the engine was warm...
Have you lubed your throttle cable? And the choke cable?
Check the routing of the throttle cable too.
No, but I will try that. I am skeptical this will work because I visually watched the carbs to see if the cable was sticking and it didn't look like it. Also, the idle will jump up soon after startup with no throttle input.
The idle screw doesn't seem to be an issue either as I screwed it all the way out.
I got my bike put back together today, and I was pretty pleased with how it was running when I started it up. Before it just wouldn't idle right no matter what I did. Even after letting it run long enough that it should've been warm I still couldn't take the choke off and get it to idle right. Well it fired right up(starter fluid is amazing, and I can't believe I never tried it before), and idled very smooth with the choke on. It didn't take long before I could turn the choke down and it still idled well. I kept it high, about 1500-2000 rpm. Once I get comfortable and trust the bike to run well I'll turn it down a little.
The only problem it's still having is when I come to a stop at a stop sign or whatever, the idle still wants to hang around 3k rpm. Slightly annoying, but no where near as annoying as having a bike that doesn't run right. For now I don't want to take the chance of pulling it apart and possibly messing something else up. Everything else works, and it runs perfect when I'm actually on it and have the rpms over 3k, so I'm just gonna get it inspected on Saturday and try to actually enjoy it for a bit. I'll mess with the hanging idle again when we get a couple rainy days. That'll give me a chance to change my brake fluid and put the clipons back on. I was super excited to try those renthals, but from the 5 minutes I've ridden, I've gotta say I HATE them. I'm fine with not leaning completely forward to reach the bars, but I hate the fact that my arms are going straight forward. I feel like my arms at least should go downward. I'll give it a few rides just to be sure, but I think clipons are definitely the way to go.
Could a hanging idle be caused by unbalanced carbs? I balance mine using the eyeball method but I am pretty much at my wits end.
I don't know what unbalanced carbs do. They seems to be pretty rare around here. I'm guessing there's a better chance that my float heights are off, but I'll figure that out later. Air leaks often seem to be a problem too, but I can't find one for the life of me.
As far as hanging idles go.... now that I've taken my bike more than 2 blocks from my house, I've actually gotten it over 4k rpm, so I'm getting a little more used to what it's doing. The idle only hangs high if I ride the bike over 4k rpm, and regardless of what rpm I'm at when I pull the clutch in, it stays right at 4k rpm. If I'm only going 2.5k rpm and pull in the clutch it seems fine. The other thing I notice is if I'm riding slower than the engine rpms would let you believe, or even if I'm just stopped at a stop sign, and I let out the clutch just slightly, it'll drop the rpms back down to a normal idle.
Does that mean anything as far as helping me resolve anything, or are those the basic symptoms of a hanging idle? I've never really had one before to know. I had always assumed that your bike would at all times try to idle high, but mine only does it at certain times.
I can control it when I'm riding because when I start to slow down I either let the clutch out just enough to catch and drop the rpms down, or I don't even pull in the clutch until it goes under 4k, but I've got an appointment to get it inspected tomorrow at noon, and I'm not sure whether or not they're actually gonna test ride it or not, or if they'll just have me turn on the high beam and the turn signals, but I'd be worried he wouldn't pass it if he tries to stop for the first time and the rpms won't drop below 4k and he doesn't know how to make it stop.
Do most places test ride bikes when they inspect them??
At this point it's pretty much like I'm having a conversation with myself here.... but that's ok.
So I tightened up my exhaust bolts, turns out they were pretty loose, but I think the main thing that helped was waiting until my bike was completely warmed up to adjust the idle. I can get it to idle perfectly fine now. When I pull in the clutch the rpms still drop slower than I would think they're supposed to, but it's not a big deal. The reason I didn't catch it before is because they'll eventually drop to a normal idle rpm, so I never thought to adjust them further, but this time I revved the engine over 4k, so they'd get stuck there, then I'd use the idle adjuster from there. Pretty much solved the problem.
I did notice something else though... Once I've done that, the bike runs perfectly fine while it's warmed up, but come the next time I go out to go riding once my engine is cooled, it doesn't like to start just off the choke. The choke actually barely does anything, and I have to turn my idle way up high again, then ride a couple blocks until it warms up, and then readjust it to get rid of the hanging idle. Is there something else I'm still missing? I thought after I adjusted it that last time and got rid of the hanging idle it would be fine, but apparently not. It would be nice to not have to toy with those every single time I start the bike.
I never really used to care when people talked about carbs vs. FI, and even would've preferred carbs because it's something I can tear into, as opposed to computers, but at this point I think I could really really appreciate a fuel injected bike.
i know this sounds obvious, but have you checked the choke cable at the carbs to make sure the choke is actuating as it should?
Quote from: flair.14 on April 12, 2010, 03:07:40 AM
No, but I will try that. I am skeptical this will work because I visually watched the carbs to see if the cable was sticking and it didn't look like it. Also, the idle will jump up soon after startup with no throttle input.
The idle screw doesn't seem to be an issue either as I screwed it all the way out.
try checking the slack on the throttle cable?
Have you checked valve cleareance lately? The cleareance is slightly temperature dependent.
The throttle has all kinds of slack. I made sure to leave a little extra just until I get everything sorted. I didn't get to mess with the choke cable much yet. I know that's a possible cause though. I just haven't gotten to pull my tank off yet since earlier this past weekend. I did put some more slack in that line too. There could still be something hanging up at the other end, but at least I know the cable isn't too tight and staying partially open because of that.
My valves do need adjusted. I checked them over winter, and all 4 of them are too tight. The bucket still spin freely, so they weren't so tight that they were pressing on them, but they were tight enough that my smallest gauge wouldn't fit. The only reason I haven't replaced them yet is because I didn't have a way to calculate the size I need without being able to fit a gauge in there to see how tight it is now. My plan now that my bike works is to ride to a dealership to pick up a shim that's clearly too thin, just so I can stick it in all 4 and calculate the clearance. Once I do that I can get 4 proper sized shims. I just knew I'd get killed on shipping if I tried to order them all seperately online.
I really just wanted to get the bike out to ride it since it's been so long of a process by now, so I'm just taking it easy and cruising nicely, mostly around 3-4k rpm since I'm in the city. In a couple weeks it'll get another tear down to change the fork oil, brake lines/fluid, new grips, put in the R6 shock, take off the center stand, paint the tank/fairing, paint the frame black if I feel up to it, make some better brackets for my tail and seat, put the clipons back on if I don't end up getting used to these renthals. I'll get the valves properly adjusted when I do all of that.
i finally got all the parts in! i also had a hanging idle on my 92, but i got the carb parts i needed. did valve adjustment already, now onto carb rebuild. i'll let you know how my little project goes =]
tt_four: i know it's not the best way to go about it, but theoretically, if the valve bucket can still move freely, theres at least SOME space between the cam and shim. therefore, since the clearance needed is only .03-.08, you should only have to get one size down from your current shims right? +/-260 down to 255 and so forth. i guess this only works if you have access to shims easily though.. lucky for me, and i sure hope they dont change this, but i got my shims free from the dealer by exchanging mine in. i needed 3 new shims when readjusting the clearance for the 92 and they gave me an assortment of shims within the range i needed, then when i got my clearances in order i just brought back the same number they lent out to me. i plan on doing a clearance check on my 89 soon so hopefully the dealer will still be as helpful.
if i still have a hanging idle, i plan on gettin new rubber boots (from airbox to carb AND carb to head). anyone know where i can get these cheap?
I've checked and checked but I don't think I have any air leaks. I've sprayed that whole setup with wd40 like 4 times now and it doesn't do anything.
That's also what I thought for the valves. The ones I have in mine now are all either 260s or 265s. I tried putting the 260 shims in where the 265s were, but I still couldn't get my gauge in there. I'll probably have to pick up a 235 or a 240 and try to measure with those. I'll see how helpful the dealership is when I make it there.
tt_four : i'd say start at 250 but that's just me. make sure to measure with calipers too? i had a few 265 that ended up being 263 and that made a bit of a difference.
I will be rejetting my carbs to see if that stops my hanging idle. I will let you know what happens.
I've definitely been measuring mine. The one thing I was curious of when I was doing it though.... If I measure a shim with my calipers it's going to measure the highest point. Wouldn't the center of the shim wear down slightly since that's where the cam rubs it, while the outer edges would be untouched? So even if the center, where the cam rubs is 263, couldn't I still get a measurement of 265 when I measure the whole thing? Or are shims hard enough that they don't really wear down like that?
Quote from: tt_four on April 26, 2010, 04:33:01 PM
I've definitely been measuring mine. The one thing I was curious of when I was doing it though.... If I measure a shim with my calipers it's going to measure the highest point. Wouldn't the center of the shim wear down slightly since that's where the cam rubs it, while the outer edges would be untouched? So even if the center, where the cam rubs is 263, couldn't I still get a measurement of 265 when I measure the whole thing? Or are shims hard enough that they don't really wear down like that?
never thought of that.. but generally i would assume that it shouldnt matter? i'd imagine you could test by placing your thinnest feeler gauge across the shim and measuring to see the difference in measurements. not sure if it'll work, but it's worth a shot if youre really curious
so i started today by taking off the black caps to the carbs to adjust the needles, finding that there were 6 grooves in which the C clip could go. i'm assuming this means the needles were probly not stock? well i decided to be adventurous and i put them on the lowest setting (closeest to center of needle). my assumption is that the stock has the C clip about a mm from the end, and putting a washer in when rejetting would keep the black thingy from raising so high (pardon my disregard for the actual names of things)... so with the option to just lower the C clip position, i did that instead of using washers. is my process flawed??
anyways.
sorry to gloat.. but NO MORE HANGING IDLE!!! :D :D :D idles much better and is actually responsive to the idle screw
except now itll cut out if i leave the throttle barely barely open. too rich right? im gonna follow the Poor Man's Rejetting Pictorial to try and get the air screws just right.. and maybe check float heights.. i'll update when i can :laugh: :laugh:
Quote from: pandymai on April 26, 2010, 08:03:09 PM
so i started today by taking off the black caps to the carbs to adjust the needles, finding that there were 6 grooves in which the C clip could go. i'm assuming this means the needles were probly not stock? well i decided to be adventurous and i put them on the lowest setting (closeest to center of needle). my assumption is that the stock has the C clip about a mm from the end, and putting a washer in when rejetting would keep the black thingy from raising so high (pardon my disregard for the actual names of things)... so with the option to just lower the C clip position, i did that instead of using washers. is my process flawed??
Your needles are probably just from a european bike. They come stock with grooves and c-clips.
Glad to hear that it solved your problem. :thumb:
My bike has the dynojet needles in it. I've been wondering if I might do better just to stick the stock needles back in and leave the dynojet jets in there. People seem to hate DJ stuff.