i'm having problems with my gs.. it's been left for a long long time and it will start but will stumble and get with  difficulty over 2000rpm. If i try to keep it above that level it will give sometime a sudden burst but again it will stumble etc. And if i press it hard it will make a horrific metallic knocking sound, which i theink comes from the engine. I'm planning to change oil, oil filter, spark plugs and clear air filter, but when i saw that thread over here "Diagnosing "Both carbs leak Fuel"
http://gstwins.com/gsboard/index.php?topic=33930.0
and having opened my gs to do the above servicing, i realized that this carb breather tube is missing. So the question is, if i stick a tube on there, where does that have to go, where does the other end lead to?
I've looked at the images of the manual and images in gstwin.com but i still haven't figured it out. Any help (especially with image) will be very helpfull!
And what about the metallic knocking, do you think it has to do with the above situation or another problem (my gs has already 87000km on...)
Thank you in advance!
Peter

Metallic knocking sound and you need to push it past 2K - why ?

Open the motor up and look, it may be worse than your breather tube.

Breather tube missing is a good thing. Breather tube pinched shut is bad.
Dont worry, just sent that tube nowhere. To the back is fine as in the pic.

87K - OK more reason to open up and look.

Cool.
Buddha.

that'd have to be a godly breather hose to take a knock out the engine

the knocking isn't there when i start the engine. when i start it (starts from the first hit of the starter button), it sounds ok but it won't idle. when i open the throttle it stumbles at 2k rpm and when i open harder it will pass that rpm and give a burst between stumbling. The knocking appears sometimes during that outbursts and if i get softer with the throttle, it disappears.  As for opening the engine, i'm not very experienced and don't know what to open and where to look at...

If anybody can give any help for the difficulty of the engine to idle and the stumbling (reading the posts in here i got the idea that it has to do with the carbs, not sure of course... ). Anyway, i will check it out again in the evening. I will take the air filter out to clean it and hope. Thanks again Buddha and gregvhen for the answers, any thought is very very welcome

You said it sat for awhile? How long exactly? Most likely your stumbling through the rpm's is caused my dirt / old gas in the carbs.

I dont know what to tell you about the knocking in the engine..... Sounds like it's time for a rebuild. It's not as bad as you think - and there's plenty of people here that would be willing to help you out.

yeh that breather tube goes nowhere. its just to let air in and out of the carbs as fuel displaces it.

Thanks guys, so i'll stick a tube to nowhere . The truth is that the bike has been sitting for 8-9 months. I will empty the tank and pour some sparkling new petrol in. But i guess there could be mud and other slimey stuff in the carbs...  So i'm looking at the "carb cleaner" topics right now.

I'll keep you posted, especially for the knocking problem of my bike...

Could the knocking sound just be "lugging" or "pinging" from the engine not running right?

it wouldn't even bother getting a new breather hose.  what you should do is try to cover the port with some of loose filter/mesh to prevent bugs and debris from getting in there. i remember someone mention some kind of cloth and a zip-tie

yes definitely take apart the carbs. use a thin wire and make sure the passages are clean. dont loose any orings!

Is it poss` your running on one cylinder (prob` due to manky carbs) and the side that isn`t running is knocking when you rev it?

Even putting in new gas in the tank may not help much as your bowls will still have old gas in them.  There are two screws you can unscrew and bleed the bowls with.  They are easy to reach and you can drain these into a container you can see through and be able to tell how nasty the gas looks or if there is water in there.  I may be dreaming this but old gas has a very distinct smell to me.  If you read the wiki you will be blown away by how much information has been covered in there.  I bet you large money you can't have a problem with your bike that nobody here has either fixed or heard of.

The carbs are easy to remove and rebuild.  Just read and read some more.  I have yet to tear down one of these motors so I am no help whatsoever.... These guys guided me through tank rust/jetting/fuel starvation issues.  Welcome and good luck.

Scott

True - old gas doesnt smell or look like new gas. And the passageways through the carbs are so tiny that even a little bit of old gas (think syrup) can clog them. Disconnect the choke cable, throttle cable, and rubber hoses, loosen the clamps and have at it.

Just be sure to have a wide, clean work space when pulling the carbs apart. All you really need is a couple screw drivers, some carb cleaner, and an air compressor to clean out the passages.

all right guys, you 've convinced me, i'll try to mess with the carbs and see what i'll find. I hope (with a great passion indeed!) that if i fix the problem with the carbs, i won't hear that freakin knocking again, wishing what zirkonx and jay w suggested are the issue...
Firewalker it's true that this forum is a treasure if you want to know what's the deal with your bike (and if not, it surely is, of course!)
I'll keep posting (i have to find the time first for the carb-operation). Any ideas-suggestions-warnings always welcome 

For working on the carbs- first of all dont work with a lit cigarette hanging out of your mouth! Just wanted to state the obvious.

When taking the floats out, do one at a time and make sure the carbs are upside down. The only thing holding the float needle in is the float - and it will bounce across the floor quickly (ask me how i know). Do your best not to gouge any brass or aluminum while you are in there. And carb cleaner can screw up rubber (diaphrams, orings, rubber flange, etc).  Guitar strings can be used gently for cleaning out passageways. A small nylon brush works good for scrubbing the more open areas.

hello there, just an update.
I' ve removed the carbs and have them sitting in my living room. I started dismantling them for cleaning and guess what : i (almost) stripped the screws of the float bowls (not all of them, the rest are done form the previous owner  .

So i stopped myself and am going to buy one of these impact-drivers to see if they are any good (the vice-crips which is suggested will not solve my problem, as not only the outside screws are proving themselves stubborn, but also the inner ones, which i suppose i won't be able to grab with that tool, although i'm going to buy one...). Also i'm afraid to use a drill on the carbs (not very experienced with drills), even if this could be a better idea.
hmm let's see, will i find a relatively cheap impact driver that won't be a total piece of sh#t?... (a huge gap on prices, basic models from 6euros - say 8$ - and from that level straight to 30e ~40$)

Glad to hear about some progress - but keep the drill away from the carbs!

An impact driver is a great tool. Even a cheap one should last at least long enough to get the jets out.

Be very careful using an impact screwdriver on carbs,i`ve had the same prob` and stupidly had the carbs upside down on the plastic tops not supported....whack,crunch,carb tops,ouch.I got mine out in the end with small mole grips,then replaced with allen bolts.

Quote from: Big Rich on September 09, 2010, 01:16:32 AM
Guitar strings can be used gently for cleaning out passageways.

OMG I am an idiot!!!!!!!!!!!!!!!!!!!!!!!!!!!!!  As many times as I have read about doing this.  I went to the store to buy a wire brush, after having 3 of them back home, only to yank one strand out of it for this.  I have a few old sets of strings laying around.  What's even better is they are not just one size.  Better late than never for me, but thanks for posting that.

I am hoping you haven't already cracked the choke area open or that your o rings are still in there.  Look up poor mans rejetting and look at all the pics on there.  Very detailed pics and will really really help you in seeing where the stuff goes.

I got my jet kit from Buddah and put it in last night.  Complete kit!!!  Jets/needle washers/allen bolts.  No running to Home Depot.....no nothing! 

all right guys, found some time and went through the task...

But not everything is perfect. I did the thing just like Firewalker above suggested, "poor man's rejetting" with the help of pics and haynes manual. As i said before, i had the floaat bowls screws screwed up! And I bought an impact driver AND DID THE THING!

_____I belong to the supporters of the Impact driver solution, a little banging (having taken the plastic tops out @JAY W  )  and out. SOOO SWEET!!!_______


And then i stripped the carbs off, i cleaned them thoroughly (they were in deep shaZam! situation, mud rust etc) and i bolted them back in. Everything else connected to place... but the engine won't run. It has fuel, it takes fuel in (i mean there is fuel coming from the tank to the fuel filter which is just before the carbs and i can see through it), it has brand new spark plugs but it won't run. I hit the starter, it spins the engine but ...you know. 

i spinned and spinned before the battery went down, there was a bang form the exhaust, but still nothing, it wasn't going to run...

Any suggestions?
Tnaks in advance (i wouldn't have come to this point if it wasn't for you and i don't regret it)

You said it ran before the carbs got pulled and cleaned? Must have something to do with the carbs then.

Either the choke needs to be set properly (no offense), the idle screw needs adjusted, or you flooded the engine. Also, a weakened battery never helps.

If you check everything else and it looks good, pull the plugs and physically check that you are getting spark.