Possible carbueration issues... help me diagnose.

[Isotech]

ok I recently traded my 2003 Ninja 250 to a friend for his 1999 GS500E with 22 miles on the odo. He bought the bike brand new, got freaked out, and let it sit for a couple of years (about 4 hehe). He would occasionally start it, and change the gas, and the carbs have been rebuilt once due gas sitting in them. Then it sat another year until I came along.

When I picked up the bike, we got some fresh gas in it, and I took it for a test ride. I noticed that it had a horribly stumble around 4-5K RPM. After adjusting the idle speed (via the large twisty screw ) it got much better. Now it was idling at 1600RPM.

After putting another 100 miles on it I still have a stumble, not at 4-5K RPM, but rather at 1/8 to 1/4 throttle opening. After the bike was warm, I readjusted the idle to 1200RPM as per specs. This improved things greatly, but I still have a slight stumble at 1/8 to 1/4 throttle.

So I think either one or two things is happening here:
1. One of the jets are slightly plugged do to carb varnish, possible the pilot jet.
2. While my idle adjustment screw is fine, I need to adjust the air mixture screws.

Given the symptoms I listed above, what do you guys/gals think is the problem. I would like to avoid yanking the carbs just yet. I was going to wait until the 600 mile service, and rejet at that time.

I'm still a relative newbie with GS500s.  

Thanks,
Nathan

[AndyMC]

welcome to the board

nice to see another washingtonian    i love rain

[Isotech]

I like riding to much to only ride when its dry. My aerostitch helps alot. After awhile being cold wet and miserable feels fairly normal.

It also means that I get to be an elitist a**hole to all the other fair-wheather riders, and that gives me a warm fuzzy feeling.  

[JLKasper]

Nathan,

Welcome to the board.  Despite your early problems with the GS, you got the better of the deal.

If you're wanting to tackle this carburetor job yourself, I'd recommend purchasing a repair manual from either Clymer or Haynes.  Replacing the stock #37 pilot jets with #40 jets (Suzuki part # 09492-40014) should be your next order of business.  Since the orifices of these jets are barely as large as a human hair, you'll understand how critical having them clean is.  I'd recommend dismantling the carbs to give them a thorough cleaning to eliminate traces of varnish and superfine rust particles from the gas tank that settles in them.  

You can perform all of this work yourself, even if you're not mechanically inclined.  Between the manuals, the how-to section, and links to other sites, you'll find your favorite set of instructions that are understandable and clearly illustrated.

Since your GS is essentially a 'virgin", you'll probably want to search the how-to section that lists procedures for other upgrades that will make your riding experience more enjoyable.  Pablo's site lists a lot of the more popular mods on one place, and you'll want to bookmark it.

Again, welcome to the board, and don't be afraid to pick our brains.  Some of us live for that stuff!

[The Buddha]

Yea 40 pilots, and being cold and wet you have more of a problem with the stock pilots than someone say in AZ or TX. Do it and after break in some minor adjustments should leave you with a perfectly carbureted bike. THe GS makes a great Rain bike, and jetting in winter is also the best way to get a perfect jetting on the bike.
Cool.
Srinath.