First off.. hello i found the forum by googling the issues of my newly aquired 02 gs500.. seem like theres some clever people here so im going to hit you up for some tips snd hopefully start enjoying this basket case bike i just bought :technical:
So i got a deal on an 02 gs500 with issues... being the cocky bloke that i am thought i would sort it and have a ridable bike.. doh! Got me bashing my head against a wall.. so i will break it down incase anyone clever here likes puzzles or if you prefer to just take the piss outta me thats cool too O0
Symptoms.
Starts well cold with choke or half choke. races to over 5k on full so usually use half. Warms up a lil rattly but not too shabby.. when getting close to running temp i back off the choke a bit and it starts running like a turd.. will not idle unless kept above 2k (by wharever means, choke , throttle, or adjusting idle screw up.). Idles 20 mins then bogs down and stalls.. plugs show a rich condition. Can ride but gotta keep engine running at stop lights.. good top end power and highway speed fine.
What ive tested
Reset carb idle air screw to all in, then back off 2.5 turns on both carbs.
Checked operation of petcock.. diaphragm is operational with 'on' working when vacuum present and 'pri' working as just open.
Tested with fuel cap open = same result
Vacuum gauge (connected to both carbys) shows crazy vacuum bouncing all over the place (even to above zero) at bad idle but nice steady vacuum with very high choke idle or higher rpms held on by throttle).
Pulled valve cover , found timing to be correct and all valve clearances about within spec (on the sloppy side all between 0.05 and 0.1mm so atleast not tight!).
Compression test dry and cold 150/160 psi .. warm and wet was slightly more.
Fuel hose and vac for petcock all correct
Air filter had a gut full of fuel (as did the crankcase because the gumby i bought it from was storing the bike in 'pri' and the floats were set waaay too high).
Oh yeh i set the floats down to the correct height and noticed that the carbs where surprisingly clean like someone had given them a once over . Checked o rings on idle air screws and a couple jets . Can shine light through jets. No junk in seats etc.. but i didnt overhaul the whole carbs due to the kits costing over au$100 for pair.. and CVs or carbs in general are not my forte lol.. if problem is the carbs seems like BOTH have bad idle circuits which seems unlikely i guess :dunno_black:
I did check for vacuum leaks with wd40 but... i have not been suspecting vacuum keaks due to the rich (not lean) condition.. but the high idle on choke has got me confused..
Any thoughts anyone ??. Ive never seen a vacuum gauge behave like that in my life, litterally jumping from vaccuum to above 0 so fast the eye cant see bouncing around like that little needle is off his head.. but stabilizing above 2k rpm??.
These bikes seem really cool and i cant wait to have a working one and customize it etc.. but right now i cant get the basics sorted.. i feel very silly.
:mad: :cookoo:
Did you check the plugs before or after resetting the float height? Could have been two problems: Float height and vacuum leak. Did WD40 test result in anything?
The choke behavior sounds normal. The bike is supposed to sit at high RPM for a minute or so with the choke on full.
I did a search here and found two less common causes of hanging idle:
1.) Stuck throttle cable. Make sure it has slack when all the way closed.
2.) Timing off by 1 tooth. This one is really weird but may be something to check if you have exhausted all other possibilities. I'm no expert but could that result in weird vacuum behavior?
I suspect you still have high floats. And make sure those air jets in the back are clean - do not try to remove them, spray and clean em. Maybe use those hair sized cleaners.
Those let air in the pilot jet circuit. Less air = too rich.
Cool.
Buddha.
idling up to 5K is normal on choke. It's supposed to do that.
I think your float needles may be sticking. Usually when someone says "bogs" they are IME describing a lean/no-fuel condition that would actually argue that the float bowls are not filling correctly, so maybe low floats or float needles sticking closed. Maybe put it on the center stand on level ground and let it run a couple of minutes, enough to stabilize the fuel level in the carbs, then using a drain hose open the fuel tap on each carb bowl and measure how much fuel comes out. If it's about the same amount, then I'd carefully reset the float levels again and go ahead and probably replace the float needle valves while the carbs are apart just in case.
Oh one other thing, if the pilot needle o-rings are shot then it will run rich on pilot no matter what you do. And they are probably shot.
And while I'm at it, the intake boot o-rings are probably also shot, and will leak air acting like a vacuum leak and making it run super lean under load.
I'm sure you've seen this but it might help if you haven't:
https://joshkarnes.blogspot.com/2017/09/fixing-common-gs500-carburetor-issues.html
The drain and measure is not a good test. The fuel in the line is a significant portion and the bowl you drain first will have a higher volume - by a good bit.
Do U tube test, in prime for float level. Use a clear tube if you can.
Float needles also are near impossible to stick closed. The fuel pressure sitting on top of them will push them open. The 01-02 carb has many flaws, but the needle sticking open is unlikely to be one of them like the 89-00 version.
So its likely your floats are still high. Pilot needle O rings ???? I have no idea what these are - I've never seen these cos carbs don't have a "pilot needle". The only needle there is goes through the main jet. We mistakenly refer to the float stopper as float "needle". Even if it was the pilot jet - there is no O ring on the pilot jet - never has been, 89-00 nope, 01-02 nope, 04-09 Nope.
Intake boot O rings or intake manifold leak will cause it to run lean not rich.
Cool.
Buddha.
the thing you often call the "pilot screw" is the "pilot needle". it's a needle that goes in the pilot valve. Jut happens to be threaded and adjustable with a screwdriver. and it has an o-ring that will cause rich running if it's bad.
and I really do think I specifically said the intake boot o-rings being bad will cause it to run very lean. you read my post at all?
I'm going to have to stop clicking on that "Show me this post" link and leave some folks on hide.
Thankyou all for the suggestions.. as previously mentioned timing is not a tooth out.. its spot on.. float levels where high previously but i set them correctly, and allready used a capillary ( 'u hose' method) to confirm. Plugs where replaced after initial going over sorry forgot to mention.. still read rich.. i .might try a damper in line with the vacuum gauge as i since realised it may need one :icon_idea: i dunno.. but appreciate you guys offering advice
Mr72 are you talking about the smaller jet inside , revealed when float bowl is removed?. I cleaned / checked that. No o ring present on either carb. Should there be ?. Like i said im not into cvs or carbs as i previously mainly played with cars.
Read the blog post I linked above. If you remove the pilot needle (what you used to adjust the pilot mixture to 2.5 turns out) completely, then out comes a spring, a washer and a tiny o-ring in that order. That's the o-ring I am talking about.
Sorry mate.. a terminology thing.. i was calling that an idle air mixture screw cos im not too familiar with cvs. Yes i can see that would make it rich.. good suggestion but there fine. Damn
Are the jets the stock size?
When you were setting the float heights, did the float needle valve seem like it was functioning properly? Kinda springy and clicky.
Did you use any carburetor cleaning products while you still had rubber parts in the carb?
Have you looked at the other side of the carb where the diaphragms are to see if they are in good condition and if the previous owner put any washers under the needle or incorrectly assembled something. I once had a bike run like crap after cleaning the carb. Turned out I put one piece back together wrong; the little plastic piece that the spring sits on was under the needle clip instead of over it. It can be helpful to reference the parts fiche upon reassembly instead of relying on the previous condition and your memory as a guide.
Bluesmudge. Thanks i have not sprayed any non metalic parts.. carbys look very clean like PO had a crack at it. Not sure if the jets are stock as the numbers on them are not the size..(eg. 40. More like 'REU' or something written on them) like jiberish to me??.
I believe the issue is pilot curcuit related as higher rpms are crisp and responsive.. slides jump up when twsting the throttle and fall back down nicely, main jets seem to be handling high rpms fine if i understand the carb correctly.
I havnt opened the top (diaphragm section) as i thought this could not affect idle or cause the rich idle and stall condition. But hit me up if im dead wrong please!
I will do as suggested earlier and clean the pilot air holes in the filter side of carby to see if it helps.. thanks all for your thoughts.
weeee welcome,...always fun to read about someone getting it running,...especially when it's not me :2guns:
where pics? :dunno_black:
:icon_mrgreen:
Quote from: dylan13nnn on December 17, 2019, 07:17:36 PM
I believe the issue is pilot curcuit related as higher rpms are crisp and responsive.. slides jump up when twsting the throttle and fall back down nicely, main jets seem to be handling high rpms fine if i understand the carb correctly.
I havnt opened the top (diaphragm section) as i thought this could not affect idle or cause the rich idle and stall condition. But hit me up if im dead wrong please!
Probably on the right track. Just remember not to spray any carb cleaner on/in the carbs while the tops and diaphragms (or any rubber parts) are still installed. Before hitting it with any carb cleaner you need to tear it all the way down to the metal core of the carb with all o-rings and diaphragms removed. Carb cleaner will immediately damage the rubber diaphragms and will degrade o-rings.
Quote
I will do as suggested earlier and clean the pilot air holes in the filter side of carby to see if it helps.. thanks all for your thoughts.
I would think if these holes are clogged then it would be very hard to start and it wouldn't idle at all. The fact that it'll idle up to 5K with choke when cold tells me it's getting plenty of air at idle.
Truly here are my thoughts:
1. you may be just turning off the choke too early. It can take 15-20 minutes of actual running on the road, going through gears under load, for the bike to get to operating temperature. My GS500 (old version of carbs...) will not idle like without at least some choke until I have ridden about 5 minutes. So maybe you are just getting in a hurry to get it off choke and there's nothing wrong.
2. You might still have an air leak at the intake boot o-rings, which will add air variably according to load/throttle/rpm and totally screw up mixture settings. And you might have inadvertently compensated for this by making the idle too rich.
3. Something in the pilot circuit is clogged. The jet can get clogged easily, so can the channels that feed fuel to it. Or the air orifice as suggested. In any case you sort all of this out quickest and easiest by just tearing down the carbs and re-cleaning them in their entirety, replace o-rings, and reset. Trying to debug one little thing can be a fool's errand.
Cheers 72 .. #3 might be it... i have removed the boots now and o rings are definitely suss! A busy couple days coming up and it 46 degrees c outside so bugger that! but hopefully I get around to replacing and reassembling to see if thats the issue... symptoms all line up to vac leak but the wet sooty plugs have been steering me away from it indicating rich not lean... BUT... it has only ran on choke . So that may still make them read rich as turning choke off kills it (yes even after 10 . 20 or 30 minutes but thanks for pointing it out.. there are no silly suggestions).
CBR pics at the moment would be of gs parts and tools scattered accross my veranda haha.. but il post pics when its running and i start on cosmetic mods.. gonna be a rat bike so i dont have to park the sporty anywhere dodgy.. hahaha
The pilot jet sits in the bowl. There is no channels that feed to it. Its sitting in the float bowl, and the pilot jet orifice is several times smaller than the passages. Very unlikely fuel gets through the pilot without clogging it and clogs up the passage which is literally 2-3X the diameter of the hole it just passed through.
The choke circuit pulls fuel through the pilot jet. If its rich on the choke, its not plugged in it. If you want to try experimenting, put a rubber plug in place of the pilot jet and see if it will even start up on the choke. Plugged pilot = no running on choke.
I'm not sure if you tried the wd40 test for vacuum leak at intake manifold.
The air mixture screw passage could be blocked, or you may just have the throttle stop screw all the way out so its shutting the throttle completely instead of leaving a crescent when you shut the throttle.
Trouble shoot first before randomly taking stuff apart - though just by sheer luck you might get it right much faster taking apart and cleaning stuff. You have a counter intuitive problem here - or atleast a not too common one.
Cool.
Buddha.
Quote from: The Buddha on December 19, 2019, 10:06:19 AM
The air mixture screw passage could be blocked, or you may just have the throttle stop screw all the way out so its shutting the throttle completely instead of leaving a crescent when you shut the throttle.
.. which is pretty much exactly how its meant to be set up, the entire purpose of those air orifices in the venturi.
Quote from: mr72 on December 19, 2019, 12:50:47 PM
Quote from: The Buddha on December 19, 2019, 10:06:19 AM
The air mixture screw passage could be blocked, or you may just have the throttle stop screw all the way out so its shutting the throttle completely instead of leaving a crescent when you shut the throttle.
.. which is pretty much exactly how its meant to be set up, the entire purpose of those air orifices in the venturi.
Sorry no, If you don't have a crescent shaped air gap, you will not hold an idle. It would not idle with the butterflies closed.
The inlet jets in the air filter bell mouth - not the venturi allow air air to enter and fuel to mix and atomize and come out in a smooth misty spray into the air stream passing through the venturi instead of a pure stream of just gas.
Cool.
Srinath.
Hey all.. thanks for the suggestions looks like it was a vacuum leak after all (intake o rings). I feel silly but spraying the intake boots while running failed to change idle and the black sooty plugs just steered me away from a lean stall.. i guess the previous owner riding it around on choke all the time may have caused this ??. Then when i swapped out the plugs i would be running it on choke for 20 mins then less than a minute without choke before it stalls so thats why the plugs always read rich.. i guess in my head i would have expected vac leak to look like 'dry" lean plugs and high idle (hanging idle).. live and learn thankyou for all your suggestions. At the least some msintenance is done ive got clean jets, valve clearances are checked, fresh oil and new plugs. So theres that.. haha..
Onto the next problem.
With a stable idle the 'little rattly' i mentioned in my initial post is a really noticeable knock at idle that goes away at higher (about 2.5k) rpm then sounds fine. Easier to trace with a screw driver used as a stethoscope now.. left engine cover.. :icon_neutral: ..... drained the oil again to remove left (alternator) cover and inspect... appears the "starter clutch" behind the magnet drum moves about 2-3mm back and forth when manipulated by hand, sounds an awful lot like the knock I hear at idle. . Possible its bolted on loose ?. Im off to borrow a puller from my brothers workshop and remove the magnet drum n check it out. I hope its as easy as tightening bolts and adding some red thread locker.. that would be great..
As a side note theres seems to be a mm or so of end float in the crankshaft.. (guessing a mm i dont have a dial indicator here) (actually there was on the intake camshaft as well come to think of it).. i cant find anywhere what the spec is for float on this engine but i sure hope that isnt my knock.. thaat would suck!
Il report back when its running like a clock (being cocky again hahaha).
Likely not the starter clutch.
Starter clutch will make a hard metallic knock at start up if slipping, usually if its locked up, it will destroy the starter in a matter of minutes. Any other state of malfunction in it is extremely unlikely.
The magnets are intact ? then leave that assembly alone. Do not try to pull it with a sliding hammer (correct tool, or a dent puller - likely wrong tool, or some other gear puller - very very wrong tool)
The upper cam shaft to bearing end play having 1mm end play is almost normal, and will make a clacking sound at and just off idle. Nothing to worry about. But they do sell shims of 1.1mm and 1.2 and 1.3 to quieten it down.
I suspect your clacking is the only issue - and hence its done. Clacking at idle and just up off idle is there in ever bike, worse in the post 2000 ones due to shieite manufacturing form spain or wherever they made them.
Cool.
Buddha.
And the only part I believe bolted in that left cover outside of what is bolted to the cover is that rotor to the end of the crank. The clutch is bolted onto the back of the rotor, it being loose will not allow the thing to start at all. The idler is on a pivot and the starter is bolted in on the other side in the cavity under the carbs.
I suspect the starter clutch bolts being loose is what you suspect, and those if loose will hit the engine case in short order and you'd end with a lot of shrapnel and a DOA motor in very short order, pretty sure its not happening.
BTW is that pinned/riveted on or bolted on ? Check it - if its pinned on, you don't need to remove it to check if a bolt is walking on you.
I have seen it both types even just on Suzuki GS based bikes, the katana motors were bolted on but an entirely different type, not the sprag like we have, something stupid with 100's of teeth and if you ever let those get out, you cant tell which way each tooth goes and no way to even hold it together. A Suzuki savage OTOH has similar teeth, but they're held in by a wire running around and cant escape.
Cool.
Buddha.
https://youtu.be/QbneQjTWnqU
Thanks buddha
I can move the clutch around back n forth independently from the magnet drum.. its supposed to be held tight with three bolts . like the guy here.. mine still atached for now.. but i definitely have that wriggle there.. something wrong with me welding a 14x1.5 bolt to a slide hammer putting a cushion on the ground to break the fall and knocking it off ?. Doesnt seem to brutal to break the interference fit even if those magnets are quite brittle and damage easily?
Wait - you have that off already and you can move that bolted on piece - and those bolts are not loose ???
You have a set of wallowed out holes on that donut in your hand. Or the bolts have necked off from wear. Find out what, the bolts are cheap, but that donut in your hand - may be $$$$ if even available.
I've never seen that part wiggle - and never seen those bolts even come loose either, they are loctited from the factory BTW.
Anyway this part does not need sliding hammer or the 14mm axle - you can take off those 3 bolts and see where the wear is. Maybe sleeve that donut if the wear is in it from wallowed out holes.
Cool.
Srinath.
U missunderstand. That is a screenshot from youtube . Mine is not off yet.. but that part wiggles just like the one on the youtube video. With the magnet drum held tight the clutch part wobbles like the one in pic.. (still atached to the bike) when i wobble it i hear the metalic knock that i herd at idle. Doesnt matter lol.. il report back when im home and i have mine off tommorow .. cheers
OK if you hold the magnet, that collar/donut rotates ???
OK I've not heard of that happening, but open it up and check the bolts etc, you really hope its bolts that have got wear on the threads, if its the donut, you're gonna have to sleeve it, I suspect its $$$$ if even available.
Cool.
Buddha.
Check this out..
Even though that looks terrible and ive surely found the source of the noise. It looks like the design is such that the one way 'clutch' (whatever the hell its called) is hub centric and relies on the clamping force of the three bolts securing into there seats to secure it tightly to the 'magnet drum' (or whatever the hell thats called). Sleeving will not be required. If it was stud centric the bolts would be designed with a shoulder where the chopped out threads are now and not threaded right to the head of the bolt. Suzuki know what there doing i reckon, and they haven't designed it to be secured by the threaded shaft of the bolt. But rather the bolt seating and clamping. Lucky the 'seats' for the bolt head are intact and arent chopped out. I will be replacing the bolts with new equivelant high tensile allen head bolts using red loctite and reassembling when i have time.. 👌. Another roblem solved and thankyou to everybody for your input.
Good thing you caught it early. I let mine go until all three bolts sheared off and locked up the generator rotor. That required some damage control. You get away with replacing some bolts.
Dude i dont know how you put up with the noise! Sounded like a spun bearing (at idle only).
Omfg yes! Those stupid questions have gone away everytime i post now! I guess the factory loctite wears off after so many km there was no evidence of loctite on my bolts.. :dunno_black:
My 48K 89 with starter clutch problem had the bolts and the donut nearly pristine. The rotor wasn't coming off the crank, and the rotor was toast anyway, I let the clack stay clacking too long, and the vibration destroyed the magnets it was on so tight, I had to weld the axle onto the rotor, heat the rotor before it will slide off the crank. The donut was mint, one of the springs had busted etc etc.
This wear on lower mile and post 2000 bikes seems to be related to poor manufacturing quality.
Cool.
Srinath.
Quote from: The Buddha on December 23, 2019, 07:39:32 AM
This wear on lower mile and post 2000 bikes seems to be related to poor manufacturing quality.
After my starter clutch bolts sheared off, I replaced my entire generator rotor/starter clutch assembly with a pristine unit from an '89 bike hoping that maybe the manufacturing quality was better in the early bikes. The magnets look different. Items like the very nice aluminum shock knuckle and clip on bars on the '89 bikes has lead me to believe that Suzuki hadn't fully implemented their cost cutting measures for 1989 bikes and hopefully the starter clutch is more reliable :dunno_black:
This is what mine looked like after letting it go too long:
(http://www.billycreek.net/photos/sc_5%20copy.jpg)
(http://www.billycreek.net/photos/sc_1%20copy.jpg)
(http://www.billycreek.net/photos/sc_6%20copy.jpg)
(http://www.billycreek.net/photos/sc_7%20copy.jpg)
I fixed it 10,000 miles ago. The repair seems to have worked, despite all the metal and magnetic bits I found in the sump.
Wow!! Looks like not an uncommon issue.. i agree things are manufactured without due care ..
Anyway, just wanted to report back to all whom offered there help and advice the engine is running like a swiss watch and idling beautifully at about 1100 rpm with no suss noises!. I can hear the beautiful sound of correctly adjusted valves and the slightly obnoxious exhaust note from the w@nk cannon the PO has installed.. its christmas eve so unfortunately im busy but cant wait to road test.. have a good Christmas.
These bikes appear to have 3 stages in terms of QC. 89-96 seems to be class 1, 96-00 seems to be class 2, the 01/02 I don't know where they fall, but the 04 and later, made in spain ones are the worst.
Still if it starts to make a rattle I'd hope you'd have got after it, but then again, mine was clacking at starting for over a year before I felt it seemed very much more shaky and out of balance one day, yea it sure was, it had lost 1/2 the magnet to that clacking and related vibration.
Cool.
Srinath.