Hello GStwins.com Forum members! My name is Robert,  I Just purchases a 1997 Suzuki GS500 (8400 miles on it). I have read so many good reviews on it and love the way it looks and feels. As a starter bike, I believe that I will own this bike for a while. I got the bike for a real nice trade (friend), cash-wise it was around $700. So I knew that I would have to do some work to it, but it was running great a year ago.


Some history of the bike... I purchased it from a friend that had it sitting in his garage for about a year. There was gas left in it. Drained old gas and replaced with new. Changed the oil as well. It was running, but not the greatest. Eventually I noticed that there was gas in the crankcase. It could not have been in there for more than 2 hours ( I'm hoping anyhow) as I noticed gas spurting out from the exhaust. I flushed the crankcase out as soon as I noticed it, changed the oil and cleaned the air box out very well.  I took off the carburetors and cleaned them very well, as they needed it. Hooked everything back up, and this is where I am....

I want to say first of all, I have been searching for problems as I am no mechanic by any means, but I would like to learn all of this as it's a lot cheaper =P.  All the work that I have done to it so far has been the help of reading this forum and some others, but I'd prefer to stay on this forum =D

I am able to get the bike to crank without the choke on, so that's a good sign I am guessing. But the idle is very low, around maybe 500RPM or so. I can get it to about 1200RPM, but then the RPM's gradually increase without touching the throttle. The most that it has went up to was around 6000RPM, but I know that it would have went higher if I had not killed it when it got that high.  Now I want to explain the throttle issue so its clear. I start the bike, it idles around 1200RPM, then starts to increase without me touching the throttle at all. I have to turn the bike off because it increases so fast and high. Its not because I am turning to the right, I had that problem already and fixed it. it just increases on its own.

I have looked this up and can not find anything on it, maybe I am wording it different. Any help would me much appreciated. I will be tinkering with it tomorrow morning =D.

You have an air leak or something is way clogged..(Pilot jets...). With a bike that old you may also have cracked intake boots ( between the head and the carbs )-big air leak.
Fuel in the crankcase is usually  a stuck or bad needle valve/seat. Did you put all the old parts back in or get new? That bike is 14 years old....things go bad...dry rot... air leaks  make it lean and it will rev ( look up hanging idle..).
Check your vacuum lines too.


Haven't used this brand yet but this is what I am referring to about putting new parts in...

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=360303281205&crlp=1_263602_304642&ff4=263602_304642&viewitem=&guid=1bb9ea5412a0a0aad453b8b3ffdc8775&rvr_id=170676422890&ua=%3F*F%3F&itemid=360303281205

if you let it rev way up, what happens if you adjust the idle back down?

will it fall and die?

if you can get it to come down, ride it for 15 or 20 minutes and get the engine and carbs good and hot, then set the idle to 1k

next time you start cold it won't idle without the choke, but thats what it is there for

also clean carbs, check for air leaks, stuck float valve or float etc etc can't hurt

I did not use a rebuild kit, just took it apart and cleaned and inspected everything. there are no cracks or nicks in the o rings, and everything looks nice and shiny, minus the usual wear, as in discoloration, but I will end up buying a kit soon. As for the air leak, I believe that is the problem, I am  going to take it all apart again (Ive gotten pretty quick at doing it) and check the rubber boots. I was in such a rush to put things together yesterday as I was moving it from a buddies house to mine. So I may have not put the boot on all the way. And I know of a tiny hole in the vacuum line at the petcock, but it is really a pin hole. I am going out to get some new fuel and vacuum lines right now, maybe an inline fuel filter if I can find one locally. Thank you for the quick feedback, I will keep you guys posted. Thanks!

If you dont have leaks you dont need a rebuild.
It can be sucking air via intakes, or have a hanging throttle cable, and after those 2 check out, it can just be lean ... its set that way on all US bikes from the factory.
I sell a jet pack to fix it, but you could put in 40 non bleed pilots and 125 mains and a #4 washer or 2, set air screw to 3 and it would set it right for a stock bike. Anyway the jet pack os 25 shipped in US and 27 to most anywhere in the world.
Cool.
Buddha.

Ok, This is a huge update.... It runs... However, My right cylinder is not firing =(.The plug is sparking fine. I have not messed with the sync screws, just the idle knob. Would that explain why when I engage the throttle, it bogs down? I can slowly engage the throttle and it slowly rises, but at a certain point it bogs down.

Ok losing a cyl can be carbs or spark ... yea you're sparking, good, but does the cyl stop firing when it gets hot ? as it warms up ... but not when hot ...

Not being able to give throttle is a classic sign of a clogged pilot though. You could clean it and be sure you're flowing full in the pilot - as in open it and spray in to clean it, then check to light and see the light through.

Now when hot if it stops running it can be a ignition trigger pick up.
When warming up if it stops running it can be a tight valve.

At any/all times its likely the carbs. Oh yea look for air intake leaks and exhaust leaks. Those have the potential to cause you tons of grief.

Cool.
Buddha.

ok will pull the carbs and clean them again. also, will one cylinder not firing cause gas to come in the crankcase? I smell it in there, but its hard to tell if it was from the previous time gas went in. Also, what size orings are used in the carb? I will go to anauto parts store and get those. I cannot find a carb repair kit around jacksonville, FL

and im not sure if it stops firing or if it ever fires to be honest with you. It has been running like this, no change to the engine sound at all. So I am thinking that it has been like this since I have gotten it.

You should not be wondering why the gas smell is in the crank case, you need to get rid of it cos gasoline is both a poor lubricant and a fire hazard.
Overflowing carbs can get the gas into the oil. You need to make sure floats are right and not overflowing.

Clean carbs change oil and post back.
Cool.
Buddha.

I have noticed that the petcock (frame) is backwards from the diagram when taking it apart. My friend said to keep the petcock set to where its at now (inbetween Res and on) Could this have something to do with my problem as well? I am cleaning the carbs tonight, what is the best way to flush the crankcase?

With enough gasoline in there it has done the flushing for you. Just drain ... remember you will be getting more than the oil capacity of 3qt. Just use a big drain pan.
Backwards petcock - K I doubt it can be backwards, but post a pic.
Tank petcock can be installed backwards, however all that does is switch your main and reserve and since prime pulls from reserve it will not flow when you're out of gas in main if that makes sense.
Cool.
Buddha.

Yes, that makes sense. What I mean about backwards is... The carb line was going where the reserve line was suppose to go, on the right side of the petcock, then on the left side of the petcock, the outermost line was going to the reserve and the middle was going to the main fuel line. and of course the vacuum line was going to the left carb. I switched it where the left outermost line was going to the main fuel, left middle went to carb, and on the right side it was going to the reserve (this is how it was listed on the GStwins route diagram). I started it up and it ran ALOT smoother than it had been. Both cylinders were firing, both exhaust pipes were hot. The thing that i did notice was it had a bad hesitation in the throttle. As it warmed up it got better, but it would still bog down when i give it half  throttle,  but that is when I am revving it in neutral, not really a quick jerk on the throttle, but faster than "rolling". Seems like too much air going in at once?

I would like to say that I am not going against what you are saying and I thank you greatly for helping me out,  but I don't have a garage with lights, so I'm limited to working on it during daylight. If i had some light I'd be out there right now =D. Tomorrow I will Break down the carbs again and see about cleaning them out again, third time might be the charm =P One thing that I did not do is adjust the floats, I had no idea that you had, to let alone how to. But I think I have figured it out, although if you know of a tutorial for the GS500 carbs, that would be awesome. So far it has been a great learning experience, just cannot wait to get it running right.

Yea that lighted garage ... well, I got one but I dont do any work in there. Its crammed full of crap.
Open it up tommorow and clean and post pics ...
The tank petcock has the slot facing the right side, matter of fact if you have a long slotted screwdriver you can turn it off sitting on the right side of the bike without taking anything off the bike. That is in fact how I remove the tank on mine.
Now with that installed right the next thing is the filter inside the tank, make sure you have it put on right. One tube is longer than the other, and the petcock is detented the same way.
If that is also right, then front of the tank petcock goes to the rear of the frame, and rear of tank petcock goes to front of frame.
That's the right combo to get everything working right. Now after that if its not right some sheite is kaput.
Cool.
Buddha.

AND

Do not run a bike with gas in the crankcase.

Cool.
Buddha.

Yep, thats how it is now. Not sure why it was even put on the way it was when I had gotten it. With that said, I think the flooding was due to the petcock settings, not going to the right places, not sucking the gas how it is suppose to.  And possibly on Prime when I had it on "on". Its all hooked up right now, so will get on the carbs tomorrow.

***how do i measure the floats? And what is the measurement it is supposed to be at?**** I am still searching the net for info on it, I know it has to be out there, but may vary from carb to carb?

*EDIT*

I see your post about Blow testing (Ive done that a few times back in high school j/k). When I blow through the hose, It is just supposed to hold all the pressure or just up to a certain PSI?

I am thinking about sending them to you if I cannot get this fixed soon, I would rather learn how to do all of this as its good info to have.

Blow test is to check if it will not leak, and you should not be able to send air through it unless you're name is Luciano I guess.
To set floats, use the U tube method. I set em to top of the bowl.
Cool.
Buddha.

cool deal, will check into that. I have been reading for the last hour and may have found the problem. I noticed that an o ring fell out of the top of the carb and I could not figure out where it went. So that explains my vacuum leak I believe. That o ring is about the same size as the o ring that goes onto the float?

I will go to the hardware store tomorrow and get a bunch of o rings. I am trying to find the actual sizes of the rings used, but that's been a bit of a challenge. Will continue reading tonight to see if I missed something. Thanks again for the quick responses sir!

Yeow ... that is rookie 101, done it myself atleast 1 time that I will admit.
Its a tiny ass O ring ... not same size as float bowl one at all, its the tiniest in the carb.
However if you get a fatter O ring it will work quite well just not a larger OD one.
In a pinch I have punched out a little dot out of an inner tube and used it to get someone back on the road.
Cool.
Buddha.

ok... so cleaning the carbs the 3rd time worked. Bike is running up to par i believe. steady idle, it did have a hanging idle, but it was when it was cold. now it will let me throttle the heck out of it and will not cough. if you look into the throat, where you can see the vacuum slide, there are 2 holes there, a fuel jety and an air jet? well, the fuel jet was clogged. is that what you were telling me to clean? I will keep an update as I will give it a test run in a few. sounds very nice now. starts right up. going to check and make sure the one cylinder is firing, sounds like it, but just to make sure.