High Altitude Carb Adjustment and Cleaning

[jhead75]

Hello All,

I was hoping to get some insight and advice on my tragic situation.

So I just got my 2004 Suzuki GS500 fixed and was looking forward to a great end of Summer/ Fall season. About 3 weeks after I got it fixed I moved to Denver... didn't even think about the altitude. Anyways now it runs really rich. It pretty much won't idle (except when I find the sweet spot on the choke) and only runs when I am giving it gas. This is counter intuitive to me, I would think with less air, it would die when I gave it more gas and not the other way around.

I should also mention it sat for a while and the carbs are in dire need of a cleaning. At one point it was leaking gas. As a quick fix I put some fuel treater in it and it was running good after that at sea level.

I found some really good videos/ tutorials and think I can handle a basic carb clean, probably not ready for a full rebuild but I think I can manage getting the carburetor out and cleaning the bowls / jets.

My questions are: Does this sound like I have the problem diagnosed correctly? Do I need to buy new jets or just adjust the carburetor some how? If I do need to do any adjustments, how hard is it?

I am on the fence about whether to attempt this or just sell the bike before I make it worse. I have no garage and I don't have the money for both storage and to pay a mechanic. If I take it apart and can't fix it, I'll have to sell it for much less.

On a different note, if you are reading this and live in the Denver area, I wouldn't be opposed to learning from a good teacher and I'm sure I could scrape together enough $$ and/or beer to make it worth your while 

Edit: also while you're reading this and if you are in the Denver area, even if you cant help me but would like to ride, send me a message. If I ever get it fixed up I would love to meet some people out here

[qcbaker]

Well, if opening the choke a bit makes the bike run better, then I don't think the bike is running rich. Or, at least, not rich enough for it to not idle. Adding fuel to an already too rich mixture shouldn't make it run better.

If it sat for a while and definitely needs a carb cleaning, and you're having problems idling, I would say your pilot jet may be clogged a bit?

[jhead75]

This makes sense, it got shipped out here so maybe some debri got knocked around in there and jammed it. I plan to wake up early saturday and start playing with it.

Any advice on whether I need new jets? I know you cant see the bike, I just mean in general. When I was researching this I found someone who said you should get a smaller sized jet if you move to this high of altitude. Should I just try cleaning it or should I order new jets and swap them while I clean it?

[HPP8140]

No point ripping into carbs until you've verified your valves have clearance.

[jhead75]

Im sorry Im not familiar with what you mean. Can you be more specific or point me towards a post on here that goes into the details of this check.

By the way thank you both for the input thus far.

[jhead75]

Also to be clear, once im moving the bike runs decent Ive even been taking it to work lately. Its mostly just problematic during start up and idling, as I mentioned I can even get it to idle ok when I play with the choke.

About the only other issue I have ( which may be unrelated) is some trouble shifting into neutral while idling. I have to give it some gas and get the rpms up or it wont pop into neutral.

[The Buddha]

I thought they sell that crappy 82 octane or 35 octane or some crazy diesel mixed crap up in the high desert to make everything run great in thin air Tried that

Anyway - jet it down 1 size - if you had the stock pilots and mains, that could be ideal. Cos its lean as Kate Moss @ sea level.

Cool.
Buddha.

[HPP8140]

Im sorry Im not familiar with what you mean. Can you be more specific or point me towards a post on here that goes into the details of this check.

By the way thank you both for the input thus far.

Perform a valve adjustment.

https://www.youtube.com/watch?v=Qgm4dwy0TJ4

[jhead75]

Thanks Ill take a look at that video when I get home.

Also I havent heard of the fuel you are talking about, didnt even know I could use gas other than premium, but ill look into it

One more question on the carbs, I see alot about adjusting float levels. If it was running good at sea level should I leave the float height alone?

Thanks

[qcbaker]

Also to be clear, once im moving the bike runs decent Ive even been taking it to work lately. Its mostly just problematic during start up and idling, as I mentioned I can even get it to idle ok when I play with the choke.

About the only other issue I have ( which may be unrelated) is some trouble shifting into neutral while idling. I have to give it some gas and get the rpms up or it wont pop into neutral.

1. Textbook pilot jet symptoms. Performing the valve clearance check is good maintenance so I'm not telling you not to do that, but I would bet money your pilot jets need cleaned.

2. My bike has this problem sometimes as well. I think this is kind of common, from what I have read. Try adjusting your clutch cable and make sure it is fully engaging. Also verify your oil level is not too high. Both of these can cause shifting problems, especially at low speed/RPM or idle. If both of those seem fine and it still does it (as my bike does sometimes), I dunno.  It hasn't caused me any real problems yet, as any time I was going to put it into neutral at idle, I am parking the bike. And when I switch the engine off, it pops into neutral with no problem.

[jhead75]

Thanks everyone. I think Ill give it a shot this weekend and let you know everyone know how it goes. 

[rscottlow]

I hope you can get this worked out and enjoy the last few weeks of riding before it gets too cold. Don't be intimidated by the carb work. I bought my GS back in Feb., and didn't even know what a carburetor looked like. Since then, I've adjusted float height, cleaned the jets, and installed a new diaphragm. Look at some YouTube videos and posts on this forum, and you'll have no trouble at all. If that's your only problem, you should be able to get it taken care of in just a few hours. Good luck!

[jhead75]

Thanks for the encouragement. Im definitely a little intimidated by this. Ive found a handful of good resources so Im pretty confident on removing the carburetor and replacing the jets. Im mostly worried about adjustments, I think Im gonna spend some time tonight looking into float level adjustments and idle mixture screw adjustment (I think I read somewhere to start with three turns from the set position). Idk, the better I understand what they do the better odds of me getting it going!

[mr72]

1. Everyone is correct, your pilot jet and/or the tiny orifices that lead to it are likely clogged. Don't mess around with trying to clean it. If you tear down the carbs, replace the jets. You want the STOCK jet sizes, which run lean at sea level but should work great at elevation.

1.5. Yes you need to pull the carbs and clean them. But DO NOT SPRAY CARB CLEANER into the carbs with rubber parts in there. That means you HAVE to pull the top off and take the diaphragm OUT and set it aside before spraying carb cleaner. Carb cleaner will flat out destroy that thin rubber diaphragm, and it will rapidly degrade o-rings, so I would use it sparingly and use it without spraying into the carb ... spray some into the cap and use a q-tip. I would have on-hand a piece of 0.012" or so wire (I use a guitar string) to push through the pilot orifices when you get it torn down.

2. Once you get the jets sorted, then start with the idle mixture adjuster turned 2.5 turns out (that's the stock setting). If you don't have vacuum or fuel leaks then the bike should start and run ok that way. Remember, it should start up on choke and within a few seconds rev itself to 5K rpm or so and run like that until you remove choke. If it doesn't do that, there is something else really wrong like a bad vacuum leak.

3. These engines are terribly cold-natured. They take forever to get properly warmed up. A 10 minute ride won't do it in my experience. So you might have to taper the choke off over time, and just offer a little choke to get it to idle at ~1500 rpm. Each time you stop as the bike is warming up, you may find it idling higher and higher, just ease the choke down a teeny bit each time until you can turn it all the way off and it'll idle.

Good luck.

[jhead75]

Wait so you're saying don't try to clean them in the first sentence but then you say in point 1.5 that yes I should pull the carbs and clean them? So which are you suggesting?

I guess it doesn't matter, I pulled the carburetor out today, unfortunately the guy who owned the bike before stripped EVERY SINGLE SCREW. I wish I could find him. They aren't just kind of stripped where you can use a little trick to get them out, the phillip head is basically a circle. I'm gonna have to buy a dremel and turn them into flat heads or something.

Ahh anyway hopefully I get them out. I think this means I will just be cleaning out the bowls and replacing the jets. I'll take your advice and keep the carb cleaner away from the rest of the carburetor and just try to clean things out with the guitar string.

[Janx101]

These bikes are cold blooded for sure... but for me at least after a few mins idle at 1500-2500 with some 'choke' the bike settles down and purrs nicely... gives me enough time to put my helmet on, adjust my gloves for wrinklefree comfort and scratch the suddenly itchy spot on my ass cheek!

To have all the transmission and everything warmed right thru could take 10-20 mins

Jet size advice I'll follow Buddha every time!

[mr72]

Wait so you're saying don't try to clean them in the first sentence

I meant don't bother trying to clean the pilot jets. Just replace them.

but then you say in point 1.5 that yes I should pull the carbs and clean them? So which are you suggesting?

Pull the carbs and clean them. Have a new set of pilot jets ready to go in because if they are clogged or corroded then trying to clean them is a waste of effort.

Be sure and take the diaphragms off before you touch anything with carb cleaner. You'll be good to go.

I guess it doesn't matter, I pulled the carburetor out today, unfortunately the guy who owned the bike before stripped EVERY SINGLE SCREW.

That really stinks. Maybe you have a friend with a Dremel who can help ... In a pinch you might be able to use a file to make "flats" on the sides of the screws so you can get a wrench on them but cutting a slot is going to be more reliable...

[mr72]

These bikes are cold blooded for sure... but for me at least after a few mins idle at 1500-2500 with some 'choke' the bike settles down and purrs nicely... \

Yeah that's what I found. But it may take 10 minutes of riding before you can take it fully off of choke without it having a fussy idle, so for that time you might have to let it have 1/2, 1/4 choke, just so if you stop, it won't try to stall. After the two-minute warmup, until it's fully warm, the choke is kind of like an idle speed control for my bike. Maybe mine's unique in this way.

[Janx101]

Choke is a jet anyway... but after 2-3 mins warm-up my choke lever gets pushed forward and left there....  I do have 'unjetted' carbs... ie never modified the jets....

Yanks are the most frequent jetters! And seemingly the most frequent chasing/diagnosing subsequent carb issues!

I don't go against jetting,  just never been dissatisfied that much with my bike. .. so far!

[RichDesmond]

...the phillip head is basically a circle...

Just a heads up, those are not Phillips screws. In fact, there are no Phillips screws anywhere on your bike. The cross-head screws that look like Phillips are actually JIS (Japanese Industrial Standard), and a Phillips screwdriver will do a lovely job of rounding them out, as you've discovered.
Get a set of JIS screwdrivers and save yourself a bunch of headaches.

http://gstwins.com/gsboard/index.php?topic=69888.msg840285#msg840285

On the jetting, leave the pilot, air screws and needle alone (after cleaning, of course) and go down one or two sizes on the main.