GS1100GK Carb trouble

[Markus Likeus]

I'm at my wits end here so it is time to call in the GS Calvary to the rescue.

The GS1100GK I have has 5462 miles on it, but they are not cared for miles. I had the bike running excellent after I corrected a number of issues.
I let the bike set for 5 months and was unable to get back to it until late July. Found the tank had rusted some and bike ran rough. I removed tank, cleaned it out, its spotless inside now. Removed carburetors and found number 4 was full of rust. I separated the carburetors, disassembled and dipped them in carburetor cleaner, each one over night. Chased all passages and made sure everything was as clean as a whistle. The only parts I replaced were two float bowl gaskets and all the o-rings at manifold boots and in the carburetors. I installed a see through fuel filter with paper element at reassembly to trap any rust particles I might have missed.

My problem.
Cylinders 1 and 2 run rich. By rich I mean I can see gas vapor coming out the exhaust pipes on that side and I can see the fuel just pour through the filter.

My solutions

1. Remove and recheck everything in the carbs. reassemble and reinstall, same problem exists, duh!

2. Remove and check float height found it was incorrect so I adjusted to .880 and reinstalled carbs. No change

3. Removed carbs, I checked for fuel shut off by removing float bowls and inverting carbs ganged together. Then I applied air pressure by mouth. I could not force any of the residual fuel out around the needle and I did not see any air bubbles from the needle or the needle seat outer diameter so needle and the seat o-ring seems to be sealing. Rechecked pilot jet and main needle jet and diaphragm. Raised float height to .900. Everything looked OK so reassembled and reinstalled, no change.

4. Checked Bike cliffs site and looked at carburetor details, found I was measuring float height incorrectly. Removed carbs and set float height on all carburetors to .910-.920. Rechecked fuel shut off again, reassembled and reinstalled. NO CHANGE ARRRRRRGHHHHHGH!!!!!!!!



I have had the carburetors off 5 times now, once to clean up and 4 trying to correct this problem. The fuel seems to shut off as the engine cranks OK no hydro lock. The bike was running great as of last March. I'm guessing fuel is getting past the main needle jet or past the choke plunger or I have something else wrong and haven't discovered the obvious. None of these parts look worn and with 5400 miles on the clock why would they. So how do I test those circuits. I've had the carbs off so often that now my hands don't even get dirty. Hope someone has some ideas because I'm about ready to go out and buy a gun!

[Dave8338]

Have you checked the plugs to verify that indeed...1&2 are rich?


Are #1 and #2 firing?
Since they are on different coils, it would likely be a plug or wire problem. Is there a chance that once you adjusted the floats to the correct height (gasket on or off?) you have a couple of fouled plugs and they need to be replaced?

I like carbs. NO... I LOVE CARBS. This WILL be sorted out.

[Markus Likeus]

Hi thanks for the reply to my post. Yes I have removed the plugs. Cylinders 1 and 2 are black and wet, cylinders 3 and 4 are white and normal looking. I cleaned 1 and 2 then swapped with 3 and 4, they are new plugs. I thought I might have bad coils so I swapped both out. No change in problem. I have a set of spare carbs but they are very dirty and rusty so I could potentially swap carbs and parts around. The carbs on the bike are the original ones.

[LarryA_Texas]

Pull the vacuum line off of the #2 carb and suck on it. If, after a minute or two of sucking you taste gasoline then your petcock diaphragm is leaking. The excess fuel is running down into the #2 cyl and that would not only make it run rich, it could keep it from running at all on that cyl. That could explain the gas vapor in the left side exhaust, since 1 and 2 share a muffler.

[almarconi]

I would check the fuel level in the bowls using a piece of clear tubing. This method will show you exactly where the fuel level is and that way you can adjust your floats. Using a calipers or ruler will only get you so close, the wet method is more accurate. Incorrect float height will effect all throttle positions, from idle to WOT, so spend the time and get them set correctly.

I would remove the inline filter. There is a filter on the petcock and the needle valves have a screen.

If the petcock is original, I would replace it as a matter of maintenance.

On carbs 1 and 2, you may want to remove one of the float bowls and make sure that the needle valves are working like they should. Gas should pour out or completely stop depending on the float position. Did you inspect the seats and needle valves for wear?

[Markus Likeus]

Well LarryA your hunch payed off. I disconnected the vacuum line at the petcock and hooked up a hand vacuum pump with a liquid reservoir in between the pump and petcock. Pulled 15 inches of vacuum and got fuel where there should not be fuel. When I get a chance I'll cap the petcock vacuum port temporarily an run in prime to see if the problem clears up at idle. If it does then I'll worry with the fuel level. Right now I think I have the floats adjusted for the lowest fuel level using a float height of .910. So for just the drive way at idle this should at least idle correctly. Almarconi I have ordered the Suzuki tool to set float level but its going to be a few days getting here along with a new petcock. I'm still going to check the fuel cutoff with the carbs mounted without the float bowls. I should be able to hold the floats up by hand and in prime not have fuel expressing itself all over the place. Thanks

[LarryA_Texas]

Well LarryA your hunch payed off. I disconnected the vacuum line at the petcock and hooked up a hand vacuum pump with a liquid reservoir in between the pump and petcock. Pulled 15 inches of vacuum and got fuel where there should not be fuel. ... Thanks

That's great. You may have solved the entire problem. Once you rebuild/replace the petcock you may find it running fine. If not then keep working on the float level, etc.

I sheepishly admit that you don't actually have to taste gasoline to diagnose the leaky petcock. Good job finding another way to check it.